Synthesis, Structure, and Reactivity of Model Complexes of Copper Nitrite Reductase

The copper(I) and copper(II) complexes with the nitrogen donor ligands bis[(1-methylbenzimidazol-2-yl)methyl]amine (1-BB), bis[2-(1-methylbenzimidazol-2-yl)ethyl]amine (2-BB), N-acetyl-2-BB (AcBB), and tris[2-(1-methylbenzimidazol-2-yl)ethyl]nitromethane (TB) have been studied as models for copper nitrite reductase. The copper(II) complexes form adducts with nitrite and azide that have been isolated and characterized. The Cu(II)-(1-BB) and Cu(II)-AcBB complexes are basically four-coordinated with weak axial interaction by solvent or counterion molecules, whereas the Cu(II)-(2-BB) and Cu(II)-TB complexes prefer to assume five-coordinate structures. A series of solid state structures of Cu(II)-(1-BB) and -(2-BB) complexes have been determined. [Cu(1-BB)(DMSO-O)(2)](ClO(4))(2): triclinic, P&onemacr; (No. 2), a = 9.400(1) ?, b = 10.494(2) ?, c = 16.760(2) ?, alpha = 96.67(1) degrees, beta = 97.10(1) degrees, gamma = 108.45(1) degrees, V = 1534.8(5) ?(3), Z = 2, number of unique data [I >/= 3sigma(I)] = 4438, number of refined parameters = 388, R = 0.058. [Cu(1-BB)(DMSO-O)(2)](BF(4))(2): triclinic, P&onemacr; (No. 2), a = 9.304(5) ?, b = 10.428(4) ?, c = 16.834(8) ?, alpha = 96.85(3) degrees, beta = 97.25(3) degrees, gamma = 108.21(2) degrees, V = 1517(1) ?(3), Z = 2, number of unique data [I >/= 2sigma(I)] = 3388, number of refined parameters = 397, R = 0.075. [Cu(1-BB)(DMSO-O)(NO(2))](ClO(4)): triclinic, P&onemacr; (No. 2), a = 7.533(2) ?, b = 8.936(1) ?, c = 19.168(2) ?, alpha = 97.66(1) degrees, beta = 98.62(1) degrees, gamma = 101.06(1) degrees, V = 1234.4(7) ?(3), Z = 2, number of unique data [I >/= 2sigma(I)] = 3426, number of refined parameters = 325, R = 0.081. [Cu(2-BB)(MeOH)(ClO(4))](ClO(4)): triclinic, P&onemacr; (No. 2), a = 8.493(3) ?, b = 10.846(7) ?, c = 14.484(5) ?, alpha = 93.71(4) degrees, beta = 103.13(3) degrees, gamma = 100.61(4) degrees, V = 1270(1) ?(3), Z = 2, number of unique data [I>/= 2sigma(I)] = 2612, number of refined parameters = 352, R = 0.073. [Cu(2-BB)(N(3))](ClO(4)): monoclinic, P2(1)/n (No. 14), a = 12.024(3) ?, b = 12.588(5) ?, c = 15.408(2) ?, beta = 101,90(2) degrees, V = 2282(1) ?(3), Z = 4, number of unique data [I >/= 2sigma(I)] = 2620, number of refined parameters = 311, R = 0.075. [Cu(2-BB)(NO(2))](ClO(4))(MeCN): triclinic, P&onemacr; (No. 2), a = 7.402(2) ?, b = 12.500(1) ?, c = 14.660(2) ?, alpha = 68.14(1) degrees, beta = 88.02(2) degrees, gamma = 78.61(1) degrees, V = 1233.0(4) ?(3), Z = 2, number of unique data [I>/= 2sigma(I)] = 2088, number of refined parameters = 319, R = 0.070. In all the complexes the 1-BB or 2-BB ligands coordinate the Cu(II) cations through their three donor atoms. The complexes with 2-BB appear to be more flexible than those with 1-BB. The nitrito ligand is bidentate in [Cu(2-BB)(NO(2))](ClO(4))(MeCN) and essentially monodentate in [Cu(1-BB)(DMSO-O)(NO(2))](ClO(4)). The copper(I) complexes exhibit nitrite reductase activity and react rapidly with NO(2)(-) in the presence of stoichiometric amounts of acid to give NO and the corresponding copper(II) complexes. Under the same conditions the reactions between the copper(I) complexes and NO(+) yield the same amount of NO, indicating that protonation and dehydration of bound nitrite are faster than its reduction. The NO evolved from the solution was detected and quantitated as the [Fe(EDTA)(NO)] complex. The order of reactivity of the Cu(I) complexes in the nitrite reduction process is [Cu(2-BB)](+) > [Cu(1-BB)](+) > [Cu(TB)](+) > [Cu(AcBB)](+).     

Magnetostructural Correlations in Bis(&mgr;(2)-phenoxide)-Bridged Macrocyclic Dinuclear Copper(II) Complexes. Influence of Electron-Withdrawing Substituents on Exchange Coupling

Macrocyclic dicopper(II) complexes derived from 2,6-di(R)formylphenols and various linking diamines are surveyed and their magnetic and structural properties assessed. For those systems with "flat" dinuclear centers and no electronic perturbations associated with electron-withdrawing ligands or ligand groups, the complexes exhibit a "straight-line" relationship between exchange integral and phenoxide bridge angle. Within the angle range 98.8-104.7 degrees, 11 complexes are included with -2J in the range 689-902 cm(-)(1). When electron-withdrawing species are present, either as ligands or as groups bound to the macrocycle itself, considerable suppression of the antiferromagnetic exchange component is observed. Single-crystal X-ray diffraction studies are reported for three complexes. [Cu(2)(L1)(H(2)O)(2)]F(2)(CH(3)OH)(2) (1) crystallized in the triclinic system, space group P&onemacr;, with a = 8.1878(5) ?, b = 9.0346(7) ?, c = 10.4048(7) ?, alpha = 103.672(6) degrees, beta = 101.163(5) degrees, gamma = 104.017(5) degrees, and Z = 1. [Cu(2)(L2)Cl(2)] [Cu(2)(L2) (H(2)O)(2)]Cl(ClO(4)).5.5H(2)O (2) crystallized in the monoclinic system, space group P2(1)/n, with a = 14.4305(5) ?, b = 24.3149(8) ?, c = 18.6584(8) ?, beta = 111.282(3) degrees, and Z = 4. [Cu(2)(L3)(H(2)O)(2)](BF(4))(2) (3) crystallized in the triclinic system, space group P&onemacr;, with a = 8.6127(4) ?, b = 8.6321(7) ?, c = 10.8430(10) ?, a = 74.390(10) degrees, beta = 86.050(10) degrees, gamma = 76.350(10) degrees, and Z = 2. Square pyramidal copper ion stereochemistries are observed in all cases, with axially coordinated halogens or water molecules. Strong antiferromagnetic exchange is observed for all complexes (-2J = 784(8) cm(-)(1), Cu-O-Cu 103.65(10) degrees (1); -2J = 801(11) cm(-)(1), Cu-O-Cu 102.4(3), 107.5(3), 102.9(3), 106.1(3) degrees (2); -2J = 689(3) cm(-)(1), Cu-O-Cu 98.8(4) degrees (3)). The presence of electron-withdrawing CN groups on the periphery of the macrocyclic ligand leads to substantially reduced antiferromagnetic exchange.     

Metal Complexes of Dithiolate Ligands: 5,6-Dihydro-1,4-dithiin-2,3-dithiolato (dddt(2-)), 5,7-Dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt(2-)), and 2-Thioxo-1,3-dithiole-4,5-dithiolato (dmit(2-)). Synthesis, Electrochemical Studies, Crystal and Electronic Structures, and Conducting Properties

New precursors to potentially conductive noninteger oxidation state (NIOS) compounds based on metal complexes [ML(2)](n)()(-) [M = Ni, Pd, Pt; L = 5,6-dihydro-1,4-dithiin-2,3-dithiolato (dddt(2)(-)), 5,7-dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt(2)(-)), and 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit(2)(-)); n = 2, 1, 0] have been investigated. Complexes of the series (NR(4))[ML(2)] (R = Me, Et, Bu; L = dddt(2)(-), dtdt(2)(-)) have been isolated and characterized, and the crystal structure of (NBu(4))[Pt(dtdt)(2)] (1) has been determined {1 = C(24)H(44)NPtS(10), a = 12.064(2) ?, b = 17.201(3) ?, c = 16.878(2) ?, beta = 102.22(2) degrees, V = 3423(1) ?(3), monoclinic, P2(1)/n, Z = 4}. Oxidation of these complexes affords the corresponding neutral species [ML(2)](0). Another series of general formula (cation)(n)()[M(dmit)(2)] [cation = PPN(+), BTP(+), and (SMe(y)()Et(3)(-)(y)())(+) with y = 0, 1, 2, and 3, n = 2, 1, M = Ni, Pd] has also been studied. All of these (cation)(n)()[M(dmit)(2)] complexes have been isolated and characterized [with the exception of (cation)[Pd(dmit)(2)] for cation = (SMe(y)()Et(3)(-)(y)())(+)]. The crystal structures of (PPN)[Ni(dmit)(2)].(CH(3))(2)CO (2) and (SMeEt(2))[Ni(dmit)(2)] (3) have been determined {2 = C(45)H(36)NNiS(10)P(2)O, a = 12.310(2) ?, b = 13.328(3) ?, c = 15.850(3) ?, alpha = 108.19(3) degrees, beta = 96.64(2) degrees, gamma = 99.67(2) degrees, V = 2373(1) ?(3), triclinic, P&onemacr;, Z = 2; 3 = C(11)H(13)NiS(11), a = 7.171(9) ?, b = 17.802(3) ?, c = 16.251(3) ?, beta = 94.39(4) degrees, V = 2068(2) ?(3), monoclinic, P2(1)/n, Z = 4} NIOS salts derived from the preceding precursors were obtained by electrochemical oxidation. Electrochemical studies of the [M(dddt)(2)] complexes show that they may be used for the preparation of NIOS radical cation salts and [M(dddt)(2)][M'(dmit)(2)](x)() compounds, but not for the preparation of (cation)[M(dddt)(2)](z)() NIOS radical anion salts. The electrochemical oxidation of the [M(dtdt)(2)](-) complexes always yields the neutral [M(dtdt)(2)](0) species. The crystal structure of [Pt(dddt)(2)][Ni(dmit)(2)](2) (4) has been determined and is consistent with the low compaction powder conductivity (5 x 10(-)(5) S cm(-)(1) at room temperature) {4 = C(20)H(8)Ni(2)PtS(28), a = 20.336(4) ?, b = 7.189(2) ?, c = 14.181(2) ?, beta = 97.16(2) degrees, V = 2057(1) ?(3), monoclinic, C2/m, Z = 2}. The crystal structures of the semiconducting NIOS compounds (BTP)[Ni(dmit)(2)](3) (5) and (SMe(3))[Ni(dmit)(2)](2) (6) have been determined {5 = C(43)H(22)PNi(3)S(30), a = 11.927(2) ?, b = 24.919(2) ?, c = 11.829(3) ?, alpha = 93.11(1) degrees, beta = 110.22(1) degrees, gamma = 83.94(1) degrees, V = 3284(1) ?(3), triclinic, P&onemacr;, Z = 2; 6 = C(15)H(9)Ni(2)S(21), a = 7.882(1) ?, b = 11.603(2) ?, c = 17.731(2) ?, alpha = 77.44(1) degrees, beta = 94.39(1) degrees, gamma = 81.27(1) degrees, V = 1563(1) ?(3), triclinic, P&onemacr;, Z = 2}. The parent compound (SEt(3))[Ni(dmit)(2)](z) (unknown stoichiometry) is also a semiconductor with a single-crystal conductivity at room temperature of 10 S cm(-)(1). By contrast, the single-crystal conductivity at room temperature of (SMeEt(2))[Pd(dmit)(2)](2) (7) is rather high (100 S cm(-)(1)). 7 behaves as a pseudometal down to 150 K and undergoes an irreversible metal-insulator transition below this temperature. The crystal structure of 7 has been determined {7 = C(17)H(13)NPd(2)S(21), a = 7.804(4) ?, b = 36.171(18) ?, c = 6.284(2) ?, alpha = 91.68(4) degrees, beta = 112.08(4) degrees, gamma = 88.79(5) degrees, V = 1643(1) ?(3), triclinic, P&onemacr;, Z = 2}. The electronic structure of (SMeEt(2))[Pd(dmit)(2)](2) (7) and the possible origin of the metal-insulator transition at 150 K are discussed on the basis of tight-binding band structure calculations.     

Structure of Dicopper Complexes of N,N,N',N'-Tetrakis[(2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane with Coordinated Thiocyanate Counterions

The structures of five dicopper complexes of binucleating ligand HL-H (N,N,N',N'-tetrakis[(2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane) with thiocyanate and some other counterions were investigated by the X-ray diffraction method. In Cu(2)(HL-H)(NCS)(2)Cl(2).6H(2)O.CH(3)OH, 1 (a = 12.524(5) ?, b = 14.429(4) ?, c = 16.343(3) ?, alpha = 109.01(2) degrees, beta = 92.62(2) degrees, gamma = 115.27(3) degrees, Z = 2, triclinic, P&onemacr;), one chloride is not coordinated. Distorted square pyramidal (SP) geometry is found for both CuN(3)ClN and CuN(3)ON coordination sites in which the N(3) tripodal coordination sites come from the two symmetric halves of HL-H and the other nitrogen atoms come from thiocyanate ions. In Cu(2)(HL-H)(NCS)(2)(ClO(4))(2).6H(2)O.2EtOH, 2 (a = 10.955(2) ?, b = 15.366(5) ?, c = 18.465(9) ?, alpha = 65.57(4) degrees, beta = 89.73(3) degrees, gamma = 79.81(2) degrees, Z = 2, triclinic, P&onemacr;), the coordination environments for the two copper ions are both CuN(3)ON. However, their geometries are different: one is distorted SP and the other is distorted trigonal bipyramid (TBP). In Cu(2)(HL-H)(NCS)(2)(ClO(4))(2)Cl.H(3)O.3.5H(2)O, 3 (a = 11.986(6) ?, b = 12.778(5) ?, c = 17.81(1) ?, alpha = 82.41(4) degrees, beta = 75.44(5) degrees, gamma = 78.46(4) degrees, Z = 2, triclinic, P&onemacr;), the chloride ion does not coordinate to copper ion, but it is hydrogen bonded to the hydroxy hydrogen. The coordination environments for the two copper ions are both CuN(3)ON with distorted SP geometries. In Cu(2)(HL-H)(NCS)Cl(3).6H(2)O, 4 (a = 12.026(5) ?, b = 14.369(6) ?, c = 16.430(6) ?, alpha = 111.64(3) degrees, beta = 90.51(4) degrees, gamma = 113.90(3) degrees, Z = 2, triclinic, P&onemacr;), one chloride does not coordinate. The coordination environments for the two copper ions are CuN(3)ON in severely distorted TBP geometry and CuN(3)Cl(2) in SP geometry. In Cu(2)(HL-H)(NCS)(3)OH.2H(2)O.3CH(3)OH.Et(2)O, 5 (a = 18.322(5) ?, b = 15.543(6) ?, c = 19.428(7) ?, beta = 102.78(3) degrees, Z = 4, monoclinic, P2(1)/c), the hydroxide ion does not coordinate. The coordination environments for the two copper ions are CuN(3)N(2) with a geometry inbetween SP and TBP but slightly closer to SP and CuN(3)ON in distorted SP geometry. The distances between the copper ions are in the range 4.45-7.99 ?, indicating negligible interaction between the copper ions. The hydroxy groups of HL-H in 1-5all coordinate to copper ions either in a terminal mode (in complexes 1, 4, and 5, denoted as OHR(t)) or in a bridging mode (in complexes 2 and 3, denoted as OHR(b)). These hydroxy groups do not lose their protons in all cases. All thiocyanate anions coordinate to copper ions through nitrogen atoms. All copper ions in 1-5 are pentacoordinated. The fact that the CuN(3) geometries of the tripodal coordination sites in HL-H do not allow the formation of a square planar complex, may be the driving force for the formation of pentacoordinated complexes. From the structurally known dicopper complexes of the HL-H type ligands, the relative coordinating abilities of ligands to CuN(3) are OHR(t) > NCS(-) > Cl(-)(t) > OHR(b) approximately Cl(-)(b), where the letters b and t in parentheses denote bridging and terminal coordination modes respectively.     

Synthesis and Characterization of Six-Coordinate Nitrido Complexes of Vanadium(V), Chromium(V), and Manganese(V). Isolation of a Dinuclear, Mixed-Valent &mgr;-Nitrido Chromium(III)/Chromium(V) Species

Photolysis of a series of octahedral monoazido complexes of the type [LM(III)(didentate ligand)(N(3))](n)(+)X(n) of vanadium(III), chromium(III), and manganese(III) in the solid state or in solution yields quantitatively the corresponding six-coordinate nitrido complexes [LM(V)(didentate ligand)(N)](n)(+)X(n) and 1 equiv of dinitrogen. L represents the macrocycle 1,4,7-triazacyclononane or its N-methylated derivative (L'), the didentate ligands are pentane-2,4-dionate (acac), 2,2,6,6-tetramethylheptane-3,5-dionate (tacac), picolinate (pic), phenanthroline (phen), and oxalate (ox), and X(-) represents perchlorate or hexafluorophosphate. The following nitrido complexes were prepared: [LV(V)(N)(acac)](ClO(4)) (6), [LCr(V)(N)(acac)](ClO(4)) (13), [LCr(V)(N)(tacac)](ClO(4)) (14), [LCr(V)(N)(pic)](ClO(4)) (15), [LCr(V)(N)(phen)](ClO(4))(2) (16), [LCr(V)(N)(ox)] (19), [L'Mn(V)(N)(acac)]PF(6) (21). Photolysis of [LCr(III)(N(3))(ox)] (17) in the solid state produces the &mgr;-nitrido-bridged mixed-valent species [L(2)Cr(2)(ox)(2)(&mgr;-N)](N(3)) (18). The structures of the precursor complex [L'Mn(acac)(N(3))]BPh(4) (20), of 13, and of [L'Mn(V)(N)(acac)]BPh(4) (21) have been determined by X-ray crystallography. Complex 13 crystallizes in the orthorhombic space group Pnma, with cell constants a = 27.187(5) ?, b = 9.228(2) ?, c = 7.070(1) ?, V = 1773.7(6) ?(3), and Z = 4; complex 20 crystallizes in the triclinic space group P&onemacr; with a = 14.769(5) ?, b = 16.83(1) ?, c = 16.96(1) ?, alpha = 108.19(5) degrees, beta = 105.06(4) degrees, gamma = 99.78(4) degrees, V = 3719(2) ?(3), and Z = 4; and complex 21 crystallizes in the monoclinic space group P2(1)/n with a = 10.443(3) ?, b = 16.035(4) ?, c = 21.463(5) ?, beta = 95.76(1) degrees, V = 3575.9(14) ?(3), and Z = 4. The Cr(V)&tbd1;N and Mn(V)&tbd1;N distances are short at 1.575(9) and 1.518(4) ?, respectively, and indicate a metal-to-nitrogen triple bond.     

Bis(1,2-bis(diphenylphosphino)ethane)tungsten(0) Complexes Containing Electron-Saturated Metal Centers and Singly-Coordinated Bridging Ligands

Reaction of 1,4-diisocyanobenzene or 4-isocyanobenzonitrile with trans-W(N(2))(2)(DPPE)(2) (DPPE = 1,2-bis(diphenylphosphino)ethane) produced cis-WL(2)(DPPE)(2), where L = 1,4-diisocyanobenzene or 4-isocyanobenzonitrile. cis-(CNC(6)H(4)NC)(2)W(DPPE)(2) crystallizes in the triclinic space group P&onemacr;, with a = 12.848(3) ?, b = 13.596(3) ?, c = 19.072(3) ?, alpha = 78.99(2) degrees, beta = 70.66(2) degrees, gamma = 65.26(2) degrees, V = 2849.8(11) ?(3), and Z = 2. cis-(NCC(6)H(4)NC)(2)W(DPPE)(2) crystallizes in the triclinic space group P&onemacr;, with a = 12.712(3) ?, b = 13.700(3) ?, c = 19.109(3) ?, alpha = 77.91(2) degrees, beta = 70.63(2) degrees, gamma = 64.76(2) degrees, V = 2830.7(13) ?(3), and Z = 2. Both compounds possess a distorted octahedral geometry about the metal center, with the two isocyanide ligands cis to one another. The isocyanide ligands are substantially bent along the CNC axis of the isocyanide group coordinated to tungsten. For the complex containing the symmetric ligand, CNC(6)H(4)NC, the mean CNC angle for the coordinated end of the isocyanide is 139.1(11) degrees, the average W-C bond length is 1.86(1) ?, and the C&tbd1;N bond lengths have a mean value of 1.30(2) ?. These data indicate substantial back-donation from an electron-saturated tungsten atom. This is supported spectroscopically, with substantial shifts to lower wavenumbers for the C-N stretching frequencies of the coordinated isocyanide groups. Similar trends are observed in cis-(NCC(6)H(4)NC)(2)W(DPPE)(2). Both compounds contain electron-rich metals surrounded by large ligands which apparently protect the metals from atmospheric oxidation. The isocyanide ligands in both complexes contain a second coordinating group pointing away from the metal into the environment surrounding the molecules, providing the potential for polymetallic complexes containing metals in a variety of oxidation states.     

Structural and Electrochemical Comparison of Copper(II) Complexes with Tripodal Ligands

A series of copper(II) complexes with tripodal polypyridylmethylamine ligands, such as tris(2-pyridylmethyl)amine (tpa), ((6-methyl-2-pyridyl)methyl)bis(2-pyridylmethyl)amine (Me(1)tpa), bis((6-methyl-2-pyridyl)methyl)(2-pyridylmethyl)amine (Me(2)tpa), and tris((6-methyl-2-pyridyl)methyl)amine (Me(3)tpa), have been synthesized and characterized by X-ray crystallography. [Cu(H(2)O)(tpa)](ClO(4))(2) (1) crystallized in the monoclinic system, space group P2(1)/a, with a = 15.029(7) ?, b = 9.268(2) ?, c = 17.948(5) ?, beta = 113.80(3) degrees, and Z = 4 (R = 0.061, R(w) = 0.059). [CuCl(Me(1)tpa)]ClO(4) (2) crystallized in the triclinic system, space group P&onemacr;, with a = 13.617(4) ?, b = 14.532(4) ?, c = 12.357(4) ?, alpha = 106.01(3) degrees, beta = 111.96(2) degrees, gamma = 71.61(2) degrees, and Z = 4 (R = 0.054, R(w) = 0.037). [CuCl(Me(2)tpa)]ClO(4) (3) crystallized in the monoclinic system, space group P2(1)/n, with a = 19.650(4) ?, b = 13.528(4) ?, c = 8.55(1) ?, beta = 101.51(5) degrees, and Z = 4 (R = 0.071, R(w) = 0.050). [CuCl(Me(3)tpa)][CuCl(2)(Me(3)tpa)]ClO(4) (4) crystallized in the monoclinic system, space group P2(1)/a, with a = 15.698(6) ?, b = 14.687(7) ?, c = 19.475(4) ?, beta = 97.13(2) degrees, and Z = 4 (R = 0.054, R(w) = 0.038). All the Cu atoms of 1-4 have pentacoordinate geometries with three pyridyl and one tertiary amino nitrogen atoms, and a chloride or aqua oxygen atom. Nitrite ion coordinated to the Cu(II) center of Me(1)tpa, Me(2)tpa, and Me(3)tpa complexes with only oxygen atom to form nitrito adducts. The cyclic voltammograms of [Cu(H(2)O)(Me(n)()tpa)](2+) (n = 0, 1, 2, and 3) in the presence of NO(2)(-) in H(2)O (pH 7.0) revealed that the catalytic activity for the reduction of NO(2)(-) increases in the order Me(3)tpa < Me(2)tpa < Me(1)tpa < tpa complexes.     

Structural and Functional Models for the Dinuclear Copper Active Site in Catechol Oxidases: Syntheses, X-ray Crystal Structures, Magnetic and Spectral Properties, and X-ray Absorption Spectroscopic Studies in Solid State and in Solution

Two novel tridentate dinucleating ligands containing benzimidazole were prepared, 1,3-bis(2-benzimidazolyl)-2-propanol (Hbbp, 1) and 1,5-bis(2-benzimidazolyl)-3-pentanol (Hbbpen, 2). Their complexing properties toward copper were studied in order to obtain structural and functional models for catechol oxidases. Syntheses and crystal structures of dinuclear Cu(II) complexes derived from these ligands are reported. [Cu(2)bbp(2)](ClO(4))(2).2MeOH, 3, crystallizes in the triclinic space group P&onemacr; with the following unit cell parameters: a = 7.702(3) ?, b = 10.973(6) ?, c = 12.396(6) ?, alpha = 100.59(4) degrees, beta = 99.02(4) degrees, gamma = 98.90(4) degrees, V = 998.7(8) ?(3), and Z = 1. [Cu(2)bbpen(2)](ClO(4))(2).3MeOH, 4, crystallizes in the orthorhombic space group Pccn, with the following unit cell parameters: a = 17.478(9) ?, b = 18.795(8) ?, c = 13.888(6) ?, V = 4562.2(4) ?(3), and Z = 4. Magnetic susceptibility measurements in the temperature ranges 4.6-459 K (3) and 4.6-425 K (4) indicate an antiferromagnetic coupling between the Cu(II) centers of both complexes. In order to determine the structures of the complexes in solution, XAS spectra (EXAFS and XANES) were recorded in the solid state and in solution. The interpretation of these data, including multiple scattering calculations, together with UV-vis titrations, shows that the complexes have the same structure in the crystalline state as well as in methanolic solution. Complex 4 is able to oxidize 3,5-di-tert-butylcatechol (3,5-DTBC) to the quinone (catecholase activity). This reaction was also studied by XAS and UV-vis spectroscopy. These measurements reveal the reduction of Cu(II) to Cu(I) accompanied by a decrease of the coordination number.     

Hydrocarbon-Soluble Mercuracarborands: Syntheses, Halide Complexes, and Supramolecular Chemistry

The syntheses of macrocyclic species composed of carborane derivatives joined via their carbon vertices by electrophilic mercury atoms are described. The reaction of closo-1,2-Li(2)[C(2)B(10)H(10)(-)(x)()R(x)()] with HgI(2) gives Li(2)[(1,2-C(2)B(10)H(10)(-)(x)()R(x)()Hg)(4)I(2)] [R = Et, x = 2 (5.I(2)Li(2)); R = Me, x = 2 (6.I(2)Li(2)); R = Me, x = 4 (7.I(2)Li(2))]. 6.I(2)(K.[18]dibenzocrown-6)(2) crystallizes in the monoclinic space group C2/m [a = 28.99(2) ?, b = 18.19(1) ?, c = 13.61(1) ?, beta = 113.74(2) degrees, V = 6568 ?(3), Z = 4, R = 0.060, R(w) = 0.070]; 7.I(2)(NBu(4))(2) crystallizes in the monoclinic space group P2(1)/c [a = 12.77(1) ?, b = 21.12(2) ?, c = 20.96(2) ?, beta = 97.87(2) degrees, V = 5600 ?(3), Z = 2, R = 0.072, R(w) = 0.082]. The precursor to 7, closo-8,9,10,12-Me(4)-1,2-C(2)B(10)H(8) (4), is made in a single step by reaction of closo-1,2-C(2)B(10)H(12) with MeI in trifluoromethanesulfonic acid. The free hosts 5, 6, and 7 are obtained by reaction of the iodide complexes with stoichiometric quantities of AgOAc. A (199)Hg NMR study indicates that sequential removal of iodide from 5.I(2)Li(2) and 6.I(2)Li(2) with aliquots of AgOAc solution leads to formation of two intermediate host-guest complexes in solution, presumed to be 5(6)ILi and 5(2)(6)(2).ILi. Crystals grown from a solution of 6.I(2)Li(2) to which 1 equiv of AgOAc solution had been added proved to be an unusual stack structure with the formula 6(3).I(4)Li(4) [tetragonal, I4/m, a = 21.589(2) ?, c = 21.666(2) ?, V = 10098 ?(3), Z = 2, R = 0.058, R(w) = 0.084]. Addition of 2 equiv of NBu(4)Br ion to 5 or 6 gives 5.Br(2)(NBu(4))(2) and 6.Br(2)(NBu(4))(2), respectively, while addition of 1 equiv of KBr to 6 forms 6.BrK. 5.Br(2)(NBu(4))(2) crystallizes in the triclinic space group P&onemacr;, [a = 10.433(1) ?, b = 13.013(1) ?, c = 15.867(2) ?, alpha = 91.638(2) degrees, beta = 97.186(3) degrees, gamma = 114.202(2) degrees, V = 1492 ?(3), Z = 1, R = 0.078, R(w) = 0.104]. The hosts 5 and 6 form 1:1 supramolecular adducts with the polyhedral anions B(10)I(10)(2)(-) and B(12)I(12)(2)(-) in solution.     

Technetium(III), Technetium(II), and Technetium(I) Complexes with Pyridine Ligands. Can Pyridine Coordination Stabilize the Low Oxidation States of Technetium?

The substitution chemistry of TcCl(3)(PPh(3))(2)(CH(3)CN) is rather facile relative to the analogous rhenium complex, since both the chloride and phosphine ligands are easily substituted for various pyridine ligands. Consequently a series of Tc(III) complexes with amine, pyridine, and polypyridyl ligands were prepared and characterized by (1)H NMR and cyclic voltammetry. In addition, the zinc reduction of TcCl(4)(py)(2) in the presence of pyridine results in TcCl(2)(py)(4). Structural and spectroscopic data indicate that this Tc(II) complex exhibits strong metal-pyridine interactions characteristic of low-valent amine complexes of Re(II) and Os(II). For example, a decrease of 0.04 and 0.06 ? is observed for the trans-Tc-N bond length in TcCl(2)(py)(4 )relative to mer-TcCl(3)(pic)(3) and [TcCl(2)(py)(3)(PPh(3))](+), respectively. This ability of pyridine to function both as a strong sigma-donor and moderate pi-acid ligand has resulted in the isolation of technetium complexes in various oxidation states with similar ligand environments. As a result, a structural comparison of [TcCl(2)(py)(3)(PPh(3))](+), TcCl(2)(py)(4), TcCl(tpy)(py)(2), and other known Tc(III) and Tc(II) pyridine complexes is presented. Crystals of [TcCl(2)(py)(3)(PPh(3))]PF(6) are triclinic, with space group P&onemacr;, Z = 2, and lattice parameters a = 12.677(4) ?, b = 13.064(4) ?, c = 13.103(5) ?, alpha = 110.14(3) degrees, beta = 101.12(3) degrees, gamma = 96.61 degrees, V = 1959 ?(3), and R = 0.0615 (R(w) = 0.1148). Crystals of TcCl(2)(py)(4) are tetragonal, with space group I4(1)/acd, Z = 8, and lattice parameters a = 15.641(4) ?, c = 16.845(6) ?, V = 4121 ?(3), and R = 0.0373 (R(w) = 0.0290). Crystals of TcCl(tpy)(py)(2) are orthorhombic, with space group C222(1), Z = 4, and lattice parameters a = 9.359(3) ?, b = 16.088(6) ?, c = 18.367(4) ?, V = 2765 ?(3), and R = 0.0499 (R(w) = 0.0599).     

Synthesis of Arenethiolate Complexes of Divalent and Trivalent Lanthanides from Metallic Lanthanides and Diaryl Disulfides: Crystal Structures of [{Yb(hmpa)(3)}(2)(&mgr;-SPh)(3)][SPh] and Ln(SPh)(3)(hmpa)(3) (Ln = Sm, Yb; hmpa = Hexamethylphosphoric Triamide)

A convenient and one-pot synthetic method of lanthanide thiolate compounds was developed. An excess of metallic samarium, europium, and ytterbium directly reacted with diaryl disulfides in THF to give selectively Ln(II) thiolate complexes, [Ln(SAr)(&mgr;-SAr)(thf)(3)](2) (1, Ln = Sm; 2, Ln = Eu; Ar = 2,4,6-triisopropylphenyl), Yb(SAr)(2)(py)(4) (3, py = pyridine), and [{Ln(hmpa)(3)}(2)(&mgr;-SPh)(3)][SPh] (6, Ln = Sm; 7, Ln = Eu; 8, Ln = Yb; hmpa = hexamethylphosphoric triamide). Reaction of metallic lanthanides with 3 equiv of disulfides afforded Ln(III) thiolate complexes, Ln(SAr)(3)(py)(n)()(thf)(3)(-)(n)() (9a, Ln = Sm, n = 3; 9b, Ln = Sm, n = 2; 10, Ln = Yb, n = 3) and Ln(SPh)(3)(hmpa)(3) (11, Ln = Sm; 12, Ln = Eu; 13, Ln = Yb). Thus, Ln(II) and Ln(III) thiolate complexes were prepared from the same source by controlling the stoichiometry of the reactants. X-ray analysis of 8 revealed that 8 has the first ionic structure composed of triply bridged dinuclear cation and benezenethiolate anion [8, orthorhombic, space group P2(1)2(1)2(1) with a = 21.057(9), b = 25.963(7), c = 16.442(8) ?, V = 8988(5) ?(3), Z = 4, R = 0.040, R(w) = 0.039 for 5848 reflections with I > 3sigma(I) and 865 parameters]. The monomeric structures of 11 and 13 were revealed by X-ray crystallographic studies [11, triclinic, space group P&onemacr; with a = 14.719(3), b = 17.989(2), c = 11.344(2) ?, alpha = 97.91(1), beta = 110.30(2), gamma = 78.40(1) degrees, V = 2751.9(9) ?(3), Z = 2, R = 0.045, R(w) = 0.041 for 7111 reflections with I > 3sigma(I) and 536 parameters; 13, triclinic, space group P&onemacr; with a = 14.565(2), b = 17.961(2), c = 11.302(1) ?, alpha = 97.72(1), beta = 110.49(1), gamma = 78.37(1) degrees, V = 2706.0(7) ?(3), Z = 2, R = 0.031, R(w) = 0.035 for 9837 reflections with I > 3sigma(I) and 536 parameters]. A comparison with the reported mononuclear and dinuclear lanthanide thiolate complexes has been made to indicate that the Ln-S bonds weakened by the coordination of HMPA to lanthanide metals have ionic character.     

Stereochemical Consequences of the Bismuth Atom Electron Lone Pair, a Comparison between MX(6)E and MX(6) Systems. Crystal and Molecular Structures of Tris[N-(P,P-diphenylphosphinoyl)-P,P-diphenylphosphinimidato]bismuth(III), [Bi{(OPPh(2))(2)N}(3)], -indium(III), [In{(OPPh(2))(2)N}(3)].C(6)H(6), and -gallium(III), [Ga{(OPPh(2))(2)N}(3)].CH(2)Cl(2)

The tetraphenylimidodiphosphinate [N-(P,P-diphenylphosphinoyl)-P,P-diphenylphosphinimidate] ion forms stable tris-chelates with the Bi(III), In(III), and Ga(III) cations. The crystal and molecular structures of [M{(OPPh(2))(2)N}(3)] (M = Ga, In, Bi) were determined by X-ray diffractometry. The geometry around the bismuth atom in compound 3 displays an approximately C(3)(v)() symmetry. This arrangement suggests the presence of a stereoactive lone pair of electrons, which is located in one of the triangular octahedral faces. Derivative 3 crystallizes in the triclinic space group P&onemacr; with Z = 2, a = 14.006(6) ?, b = 14.185(4) ?, c = 17.609(8) ?, alpha = 88.45(2) degrees, beta = 79.34(2) degrees, and gamma = 78.23(2) degrees. The structures of the gallium(III) and indium(III) tris-chelate oxygen-based complexes (1 and 2, respectively) were compared with the bismuth analogue in order to determine the ligand steric bulk influence on the coordination sphere in the absence of the electron lone pair. Complex 1 crystallizes as the [Ga{(OPPh(2))(2)N}(3)].CH(2)Cl(2) solvate in the triclinic space group P&onemacr;; Z = 2, a = 13.534(4) ?, b = 13.855(4) ?, c = 18.732(7) ?, alpha = 95.48(2) degrees, beta = 98.26(2) degrees, and gamma = 97.84(2) degrees. Crystal data for the benzene solvate of 2, [In{(OPPh(2))(2)N}(3)].C(6)H(6): triclinic space group P&onemacr;, Z = 2, a = 13.542(9) ?, b = 15.622(3) ?, c = 18.063(5) ?, alpha = 98.21(1) degrees, beta = 104.77(0) degrees, and gamma = 92.260(0) degrees.     

Halide Effects in the Formation of Four-Coordinate, Cationic Aluminum

This work was conducted as part of a broad-based effort to determine the factors that affect cation formation for organometallic aluminum complexes. In this study the adduct species R(2)AlX.NH(2)(t)Bu (R, X: Me, F (1); Me, Cl (2); Et, Cl (3); Me, Br (4)) and cationic complexes [R(2)Al(NH(2)(t)Bu)(2)]X (R, X: Me, Br (5); Et, Br (6); Me, I (7)) were examined. These complexes demonstrate that the reaction of R(2)AlX with excess NH(2)(t)Bu produces cationic complexes only when X = Br or I. All of the compounds were characterized by melting points, (1)H NMR, IR, elemental analyses, and, in some cases, X-ray crystallography. X-ray data: 2, triclinic, P&onemacr;, a = 6.277(3) ?, b = 8.990(3) ?, c = 10.393(3) ?, alpha = 71.97(1) degrees, beta = 80.25(3) degrees, gamma = 81.97(3) degrees, V = 547.0(4) ?(3), Z = 2, 1032 reflections with F > 4.0 sigma(F), R = 0.0520; 5, monoclinic, P2(1)/c, a = 9.099(1) ?, b = 10.292(1) ?, c = 17.255(2) ?, beta = 104.81(1) degrees, V = 1562.1(3) ?(3), Z = 4, 1464 reflections with F > 4.0 sigmaF, R = 0.0387; 6, monoclinic, P2(1)/c, a = 14.122(2) ?, b = 13.539(2) ?, c = 21.089(2) ?, beta = 107.73(1) degrees, V = 3841.2(9) ?(3), Z = 4, 781 reflections with F > 5.0 sigmaF, R = 0.0873; 7, monoclinic, P2(1)/n, a = 9.071(1) ?, b = 10.529(1) ?, c = 17.714(2) ?, beta = 103.67(1) degrees, V = 1644.0(3) ?(3), Z = 4, 1723 reflections with F > 4.0 sigmaF, R = 0.0451.     

Bonding Properties of a Novel Inorganometallic Complex, Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) (iPr-DAB = N,N'-Diisopropyl-1,4-diaza-1,3-butadiene), and its Stable Radical-Anion, Studied by UV-Vis, IR, and EPR Spectroscopy, (Spectro-) Electrochemistry, and Density Functional Calculations

Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) was synthesized and characterized by UV-vis, IR, (1)H NMR, (13)C NMR, (119)Sn NMR, and mass (FAB(+)) spectroscopies and by single-crystal X-ray diffraction, which proved the presence of a nearly linear Sn-Ru-Sn unit. Crystals of Ru(SnPh(3))(2)(CO)(2)(iPr-DAB).3.5C(6)H(6) form in the triclinic space group P&onemacr; in a unit cell of dimensions a = 11.662(6) ?, b = 13.902(3) ?, c = 19.643(2) ?, alpha = 71.24(2) degrees, beta = 86.91(4) degrees, gamma = 77.89(3) degrees, and V = 2946(3) ?(3). One-electron reduction of Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) produces the stable radical-anion [Ru(SnPh(3))(2)(CO)(2)(iPr-DAB)](*-) that was characterized by IR, and UV-vis spectroelectrochemistry. Its EPR spectrum shows a signal at g = 1.9960 with well resolved Sn, Ru, and iPr-DAB (H, N) hyperfine couplings. DFT-MO calculations on the model compound Ru(SnH(3))(2)(CO)(2)(H-DAB) reveal that the HOMO is mainly of sigma(Sn-Ru-Sn) character mixed strongly with the lowest pi orbital of the H-DAB ligand. The LUMO (SOMO in the reduced complex) should be viewed as predominantly pi(H-DAB) with an admixture of the sigma(Sn-Ru-Sn) orbital. Accordingly, the lowest-energy absorption band of the neutral species will mainly belong to the sigma(Sn-Ru-Sn)-->pi(iPr-DAB) charge transfer transition. The intrinsic strength of the Ru-Sn bond and the delocalized character of the three-center four-electron Sn-Ru-Sn sigma-bond account for the inherent stability of the radical anion.     

Two New Antiferromagnetic Nickel(II) Complexes Bridged by Azido Ligands in the Cis Position. Effect of the Counteranion on the Crystal Structure and Magnetic Properties

Two new nickel(II) end-to-end azido-bridged compounds, cis-catena-[NiL(2)(&mgr;-N(3))](n)()(ClO(4))(n)().nH(2)O (1) and [Ni(2)L(4)(&mgr;-N(3))(2)](PF(6))(2) (2), were synthesized and characterized; L is 2-(aminoethyl)pyridine. The crystal structures of 1 and 2 were solved. Complex 1: monoclinic system, space group P2(1)/a, a = 8.637(2) ?, b = 18.9995(7) ?, c = 12.3093(7) ?, beta = 105.92(2) degrees, Z = 4. Complex 2: triclinic system, space group P&onemacr;, a = 9.139(7) ?, b = 10.124(3) ?, c = 12.024(2) ?, alpha = 70.407(14) degrees, beta = 84.19(2) degrees, gamma = 67.67(4) degrees, Z = 1. In the two complexes the nickel atom is situated in a similarly distorted octahedral environment. The two complexes are different; 1 is a one-dimensional helicoidal complex with the two L ligands and the two end-to-end azido bridges in a cis arrangement while complex 2 is a dinuclear system with two end-to-end azido bridges, indicating the extreme importance of the counteranion present (ClO(4)(-) for 1 and PF(6)(-) for 2). The magnetic properties of the two compounds were studied by susceptibility measurements vs temperature. The chi(M) vs T plot for 1 shows the shape for a weakly antiferromagnetically coupled nickel(II) one-dimensional complex without a maximum until 4 K. In contrast, for complex 2 the shape of the chi(M) vs T curve shows a maximum near 40 K, indicating medium antiferromagnetic coupling. From the spin Hamiltonian -J(ij)()S(i)()S(j)(), J values for 1 and 2 were less than -1 and -29.1 cm(-)(1), respectively. The magnetic behavior for 1 and 2 may be explained in terms of the overlap between magnetic orbitals, taking into account the torsion of the Ni(II) atoms and azido-bridging ligands in the two structures.     

Coordinatively and Electronically Unsaturated Tungsten(0) Carbonyl Complexes Stabilized by pi-Donating Amido Ligands

Novel, coordinatively and electronically unsaturated tungsten tricarbonyl dianions of 2-aminophenol and 1,2-diaminobenzene have been synthesized from the reaction of photogenerated W(CO)(5)THF and [Et(4)N][OC(6)H(4)NH(2)] with subsequent deprotonation by [Et(4)N][OH] accompanied by facile CO dissociation, and the reaction of W(CO)(5)THF and 2 equiv of [Et(4)N][NHC(6)H(4)NH(2)], respectively. These air-sensitive derivatives have been fully characterized both in solution (nu(CO) and (13)C NMR) and in the solid-state (X-ray crystallography). These metal dianions which have formally 16e(-) configurations are stabilized by pi-donation from the amido groups of the chelating ligands, as evident from short W-N bond distances. Both solution (nu(CO) and (13)C NMR) and solid-state (W-N vs W-O bond distances) data on these derivatives indicate the amido ligand to be a better pi-donor than the oxo ligand. Complex 2 crystallized in the monoclinic space group P2(1)/n with a = 14.499(5) ?, b = 14.708(5) ?, c = 15.137(4) ?, beta = 114.13(2) degrees, V = 2946(2) ?(3), and d(calc) = 1.433 g/cm(3), for Z = 4. Complex 3 crystallized in the triclinic space group P&onemacr; with a = 11.479(6) ?, b = 11.786(8) ?, c = 13.148(7) ?, alpha = 102.41(5) degrees, beta = 91.27(4) degrees, gamma = 99.96(5) degrees, V = 1708(2) ?(3), and d(calc) = 1.444 g/cm(3), for Z = 2.     

Linear Trinuclear Pt.Mo-Mo Complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CR)(2)](2) (X = Cl, Br, I; R = CH(3), C(CH(3))(3); pyphos = 6-(Diphenylphosphino)-2-pyridonate) with an Axial Interaction between the Quadruply Bonded Mo(2) Moiety and the Platinum Atom

An example of a direct axial interaction of a platinum(II) atom with a Mo(2) core through a uniquely designed tridentate ligand 6-(diphenylphosphino)-2-pyridonate (abbreviated as pyphos) is described. Treatment of PtX(2)(pyphosH)(2) (2a, X = Cl; 2b, X = Br; 2c, X = I) with a 1:1 mixture of Mo(2)(O(2)CCH(3))(4) and [Mo(2)(O(2)CCH(3))(2)(NCCH(3))(6)](2+) (3a) in dichloromethane afforded the linear trinuclear complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CCH(3))(2)](2) (4a, X = Cl; 4b, X = Br; 4c, X = I). The reaction of [Mo(2)(O(2)CCMe(3))(2)(NCCH(3))(4)](2+) (3b) with 2a-c in dichloromethane afforded the corresponding pivalato complexes [Mo(2)PtX(2)(pyphos)(2)(O(2)CCMe(3))(2)](2) (5a, X = Cl; 5b, X = Br; 5c, X = I), whose bonding nature is discussed on the basis of the data from Raman and electronic spectra as well as cyclic voltammograms. The linear trinuclear structures in 4b and 5a-c were confirmed by NMR studies and X-ray analyses: 4b, monoclinic, space group C2/c, a = 34.733(4) ?, b = 17.81(1) ?, c = 22.530(5) ?, beta = 124.444(8) degrees, V = 11498(5) ?(3), Z = 8, R = 0.060 for 8659 reflections with I > 3sigma(I) and 588 parameters; 5a, triclinic, space group P&onemacr;, a = 13.541(3) ?, b = 17.029(3) ?, c = 12.896(3) ?, alpha = 101.20(2) degrees, beta = 117.00(1) degrees, gamma = 85.47(2) degrees, V = 2599(1) ?(3), Z = 2, R = 0.050 for 8148 reflections with I > 3sigma(I) and 604 parameters; 5b, triclinic, space group P&onemacr;, a = 12.211(2) ?, b = 20.859(3) ?, c = 10.478(2) ?, alpha = 98.88(1) degrees, beta = 112.55(2) degrees, gamma = 84.56(1) degrees, V = 2433.3(8) ?(3), Z = 2, R = 0.042 for 8935 reflections with I > 3sigma(I) and 560 parameters; 5c, monoclinic, space group P2(1)/n, a = 13.359(4) ?, b = 19.686(3) ?, c = 20.392(4) ?, beta = 107.92(2) degrees, V = 5101(2) ?(3), Z = 4, R = 0.039 for 8432 reflections with I > 3sigma(I) and 560 parameters.     

An Approach to Heterometallic Complexes with Selenolate and Tellurolate Ligands: Crystal Structures of cis-[Mn(CO)(4)(SePh)(2)](-), [(CO)(3)Mn(&mgr;-SeMe)(3)Mn(CO)(3)](-), (CO)(4)Mn(&mgr;-TePh)(2)Co(CO)(&mgr;-SePh)(3)Mn(CO)(3), and (CO)(3)Mn(&mgr;-SePh)(3)Fe(CO)(3)

Oxidative addition of diorganyl diselenides to the coordinatively unsaturated, low-valent transition-metal-carbonyl fragment [Mn(CO)(5)](-) produced cis-[Mn(CO)(4)(SeR)(2)](-). The complex cis-[PPN][Mn(CO)(4)(SePh)(2)] crystallized in triclinic space group P&onemacr; with a = 10.892(8) ?, b = 10.992(7) ?, c = 27.021(4) ?, alpha = 101.93(4) degrees, beta = 89.79(5) degrees, gamma = 116.94(5) degrees, V = 2807(3) ?(3), and Z = 2; final R = 0.085 and R(w) = 0.094. Thermolytic transformation of cis-[Mn(CO)(4)(SeMe)(2)](-) to [(CO)(3)Mn(&mgr;-SeMe)(3)Mn(CO)(3)](-) was accomplished in high yield in THF at room temperature. Crystal data for [Na-18-crown-6-ether][(CO)(3)Mn(&mgr;-SeMe)(3)Mn(CO)(3)]: trigonal space group R&thremacr;, a = 13.533(3) ?, c = 32.292(8) ?, V = 5122(2) ?(3), Z = 6, R = 0.042, R(w) = 0.041. Oxidation of Co(2+) to Co(3+) by diphenyl diselenide in the presence of chelating metallo ligands cis-[Mn(CO)(4)(SePh)(2)](-) and cis-[Mn(CO)(4)(TePh)(2)](-), followed by a bezenselenolate ligand rearranging to bridge two metals and a labile carbonyl shift from Mn to Co, led directly to [(CO)(4)Mn(&mgr;-TePh)(2)Co(CO)(&mgr;-SePh)(3)Mn(CO)(3)]. Crystal data: triclinic space group P&onemacr;, a = 11.712(3) ?, b = 12.197(3) ?, c = 15.754(3) ?, alpha = 83.56(2) degrees, beta = 76.13(2) degrees, gamma = 72.69(2) degrees, V = 2083.8(7) ?(3), Z = 2, R = 0.040, R(w) = 0.040. Addition of fac-[Fe(CO)(3)(SePh)(3)](-) to fac-[Mn(CO)(3)(CH(3)CN)(3)](+) resulted in formation of (CO)(3)Mn(&mgr;-SePh)(3)Fe(CO)(3). This neutral heterometallic complex crystallized in monoclinic space group P2(1)/n with a = 8.707(2) ?, b = 17.413(4) ?, c = 17.541(4) ?, beta = 99.72(2) degrees, V = 2621(1) ?(3), and Z = 4; final R = 0.033 and R(w) = 0.030.     

N-Methyl-2-(methylamino)troponiminate Complexes of Tin(II), Gallium(III), and Indium(III). Syntheses of [(Me)(2)ATI](2)GaI and [(Me)(2)ATI](2)InCl Using the Tin(II) Reagent [(Me)(2)ATI](2)Sn

The N-methyl-2-(methylamino)troponimine [(Me)(2)ATI]H reacts with bis[bis(trimethylsilyl)amido]tin(II) to yield [(Me)(2)ATI](2)Sn in excellent yield. The treatment of [(Me)(2)ATI](2)Sn with GaI and InCl led to the bis(ligand)gallium(III) and -indium(III) compounds [(Me)(2)ATI](2)GaI and [(Me)(2)ATI](2)InCl. These metal complexes were characterized by elemental analysis, (1)H and (13)C NMR spectroscopy, and X-ray crystallography. All three metal adducts show fluxional behavior in solution at room temperature. [(Me)(2)ATI](2)Sn exhibits a pseudo trigonal bipyramidal structure in the solid state. The gallium and indium atoms in [(Me)(2)ATI](2)GaI and [(Me)(2)ATI](2)InCl adopt trigonal bipyramidal geometry around the metal center with the halide occupying an equatorial site. A convenient, high-yield route to [(Me)(2)ATI]H is also reported. Crystal data with Mo Kalpha (lambda = 0.710 73 ?) at 183 K: [(Me)(2)ATI](2)Sn, C(18)H(22)N(4)Sn, a = 8.4347(11) ?, b = 10.5564(13) ?, c = 11.5527(11) ?, alpha = 66.931(8) degrees, beta = 73.579(9) degrees, gamma = 67.437(7) degrees, V = 863.3(2) ?(3), triclinic, space group P&onemacr;, Z = 2, R = 0.0224; [(Me)(2)ATI](2)GaI, C(18)H(22)GaIN(4), a = 12.947(2) ?, b = 9.5834(9) ?, c = 16.0132(12) ?, beta = 107.418(8) degrees, V = 1895.8(3) ?(3), monoclinic, space group P2(1)/c, Z = 4, R = 0.0214; [(Me)(2)ATI](2)InCl, C(18)H(22)ClInN(4), a = 24.337(3) ?, b = 8.004(2) ?, c = 19.339(3) ?, beta = 101.537(13) degrees, V = 3691.1(11) ?(3), monoclinic, space group C2/c, Z = 8, R = 0.0224.     

Reversible Insertion of Methyl Isothiocyanate into Copper(I) Aryloxides

MeNCS undergoes insertion into the copper(I)-aryloxide bond to form [N-methylimino(aryloxy)methanethiolato]copper(I) complexes. This insertion occurs in the absence of ancillary ligands unlike the analogous insertion of PhNCS. The reaction with 4-methylphenoxide results in the formation of hexakis[[N-methylimino(4-methylphenoxy)methanethiolato]copper(I)] (1), which has been characterized by X-ray crystallography. Crystal data for 1: hexagonal R&thremacr;, a = 12.365(3) ?, c = 36.734(16) ?, gamma = 120 degrees, Z = 3, V = 4863(3) ?(3), R = 0.0306. Reactions of 2,6-dimethyl- and 4-chlorophenoxides also result in analogous copper(I) complexes 2 and 3. Addition of stochiometric amounts of PPh(3) to the oligomeric complexes typically results in the extrusion of MeNCS. The ease of extrusion is dependent on the substituents on the aryloxide, and this deinsertion is accelerated by water. However, the extrusion reaction is slow enough in the case of the N-methylimino(2,6-dimethylphenoxy)methanethiolate complex and the isolation of an intermediate monomeric product bis(triphenylphosphine)[N-methylimino(2,6-dimethylphenoxy)methanethiolato]copper(I) (4) is possible. Crystal data for 4: triclinic P&onemacr;, a = 10.088(2) ?, b = 11.302(1) ?, c = 17.990(2) ?, alpha = 94.06(1) degrees, beta = 95.22(2) degrees, gamma = 103.94(1) degrees, Z = 2, V = 1974.4(7) ?(3), R = 0.0361. In the presence of of PPh(3), the insertion reaction becomes reversible. This allows the exchange of the heterocumulene MeNCS or the aryloxy group in these molecules with another heterocumulene or a phenol, respectively, when catalytic amounts of PPh(3) are added. Oligomers with exchanged heterocumulmes and phenols could be characterized by independent synthesis.