Synthesis and structures of a pentanuclear Al(iii) phosphonate cage, an In(iii) phosphonate polymer, and coordination compounds of the corresponding phosphonate ester with GaI(3) and InCl(3)

A cationic, pentanuclear aluminium phosphonate cage, [L(4)Al(5)Cl(6)(THF)(6)]Cl, 1, supported by (phthalimidomethyl) phosphonate, (L), has been synthesized and characterized. This polynuclear cage features the phosphonate ligand in an unusual coordination mode, supporting five aluminium atoms in two different environments. In comparison, the aqueous reaction of LH(2) with In(ClO(4))(3) afforded [{(LH)In(H(2)O)}(H(2)O)(2)(ClO(4))](n), 2, an indium(iii) phosphonate coordination polymer, that has been crystallographically characterized. Reactions of the corresponding phosphonate ester, diethyl (phthalimidomethyl) phosphonate, (L'), with GaI(3) and InCl(3) afforded the simple coordination complexes, [L'·GaI(3)], 3, and [L'·InCl(3)(THF)], 4.     

Theoretical insights into the ferromagnetic coupling in oxalato-bridged chromium(III)-cobalt(II) and chromium(III)-manganese(II) dinuclear complexes with aromatic diimine ligands

Two novel heterobimetallic complexes of formula [Cr(bpy)(ox)(2)Co(Me(2)phen)(H(2)O)(2)][Cr(bpy)(ox)(2)]·4H(2)O (1) and [Cr(phen)(ox)(2)Mn(phen)(H(2)O)(2)][Cr(phen)(ox)(2)]·H(2)O (2) (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and Me(2)phen = 2,9-dimethyl-1,10-phenanthroline) have been obtained through the "complex-as-ligand/complex-as-metal" strategy by using Ph(4)P[CrL(ox)(2)]·H(2)O (L = bpy and phen) and [ML'(H(2)O)(4)](NO(3))(2) (M = Co and Mn; L' = phen and Me(2)phen) as precursors. The X-ray crystal structures of 1 and 2 consist of bis(oxalato)chromate(III) mononuclear anions, [Cr(III)L(ox)(2)](-), and oxalato-bridged chromium(III)-cobalt(II) and chromium(III)-manganese(II) dinuclear cations, [Cr(III)L(ox)(μ-ox)M(II)L'(H(2)O)(2)](+)[M = Co, L = bpy, and L' = Me(2)phen (1); M = Mn and L = L' = phen (2)]. These oxalato-bridged Cr(III)M(II) dinuclear cationic entities of 1 and 2 result from the coordination of a [Cr(III)L(ox)(2)](-) unit through one of its two oxalato groups toward a [M(II)L'(H(2)O)(2)](2+) moiety with either a trans- (M = Co) or a cis-diaqua (M = Mn) configuration. The two distinct Cr(III) ions in 1 and 2 adopt a similar trigonally compressed octahedral geometry, while the high-spin M(II) ions exhibit an axially (M = Co) or trigonally compressed (M = Mn) octahedral geometry in 1 and 2, respectively. Variable temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 and 2 reveal the presence of weak intramolecular ferromagnetic interactions between the Cr(III) (S(Cr) = 3/2) ion and the high-spin Co(II) (S(Co) = 3/2) or Mn(II) (S(Mn) = 5/2) ions across the oxalato bridge within the Cr(III)M(II) dinuclear cationic entities (M = Co and Mn) [J = +2.2 (1) and +1.2 cm(-1) (2); H = -JS(Cr)·S(M)]. Density functional electronic structure calculations for 1 and 2 support the occurrence of S = 3 Cr(III)Co(II) and S = 4 Cr(III)Mn(II) ground spin states, respectively. A simple molecular orbital analysis of the electron exchange mechanism suggests a subtle competition between individual ferro- and antiferromagnetic contributions through the σ- and/or π-type pathways of the oxalato bridge, mainly involving the d(yz)(Cr)/d(xy)(M), d(xz)(Cr)/d(xy)(M), d(x(2)-y(2))(Cr)/d(xy)(M), d(yz)(Cr)/d(xz)(M), and d(xz)(Cr)/d(yz)(M) pairs of orthogonal magnetic orbitals and the d(x(2)-y(2))(Cr)/d(x(2)-y(2))(M), d(xz)(Cr)/d(xz)(M), and d(yz)(Cr)/d(yz)(M) pairs of nonorthogonal magnetic orbitals, which would be ultimately responsible for the relative magnitude of the overall ferromagnetic coupling in 1 and 2.     

B(C6F5)3 adducts of transition metal acyl compounds

The transition metal acyl compounds [Co(L)(CO)3(COMe)] (L = PMe3, PPhMe2, P(4-Me-C6H4)3, PPh3 and P(4-F-C6H4)3), [Mn(CO)5(COMe)] and [Mo(PPh3)(eta(5)-C5H5)(CO)2(COMe)] react with B(C6F5)3 to form the adducts [Co(L)(CO)3(C{OB(C6F5)3}Me)] (L = PMe3, 1, PPhMe2, 2, P(4-Me-C6H4)3, 3, PPh3, 4, P(4-F-C6H4)3), 5, [Mn(CO)5(C{OB(C6F5)3}Me)] 6 and [Mo(eta(5)-C5H5)(PPh3)(CO)2(C{OB(C6F5)3}Me)], 7. Addition of B(C6F5)3 to a cooled solution of [Mo(eta(5)-C5H5)(CO)3(Me)], under an atmosphere of CO gave [Mo(eta(5)-C5H5)(CO)3(C{OB(C6F5)3}Me)] 8. In the presence of adventitious water, the compound [Co{HOB(C6F5)3}2{OP(4-F-C6H4)3}2] 9, was formed from [Co(P(4-F-C6H4)3)(CO)3(C{OB(C6F5)3}Me)]. The compounds 4 and 9 have been structurally characterised. The use of B(C6F5)3 as a catalyst for the CO-induced migratory-insertion reaction in the transition metal alkyl compounds [Co(PPh3)(CO)3(Me)], [Mn(CO)5(Me)], [Mo(eta(5)-C5H5)(CO)3(Me)] and [Fe(eta(5)-C5H5)(CO)2(Me)] has been investigated.     

Dinuclear cobalt(II) and copper(II) complexes with a Py2N4S2 macrocyclic ligand

The interaction between Co(II) and Cu(II) ions with a Py(2)N(4)S(2)-coordinating octadentate macrocyclic ligand (L) to afford dinuclear compounds has been investigated. The complexes were characterized by microanalysis, conductivity measurements, IR spectroscopy and liquid secondary ion mass spectrometry. The crystal structure of the compounds [H(4)L](NO(3))(4), [Cu(2)LCl(2)](NO(3))(2) (5), [Cu(2)L(NO(3))(2)](NO(3))(2) (6), and [Cu(2)L(μ-OH)](ClO(4))(3)·H(2)O (7) was also determined by single-crystal X-ray diffraction. The [H(4)L](4+) cation crystal structure presents two different conformations, planar and step, with intermolecular face-to-face π,π-stacking interactions between the pyridinic rings. Complexes 5 and 6 show the metal ions in a slightly distorted square-pyramidal coordination geometry. In the case of complex 7, the crystal structure presents the two metal ions joined by a μ-hydroxo bridge and the Cu(II) centers in a slightly distorted square plane or a tetragonally distorted octahedral geometry, taking into account weak interactions in axial positions. Electron paramagnetic resonance spectroscopy is in accordance with the dinuclear nature of the complexes, with an octahedral environment for the cobalt(II) compounds and square-pyramidal or tetragonally elongated octahedral geometries for the copper(II) compounds. The magnetic behavior is consistent with the existence of antiferromagnetic interactions between the ions for cobalt(II) and copper(II) complexes, while for the Co(II) ones, this behavior could also be explained by spin-orbit coupling.     

Dinuclear amine-thiophenolate complexes coligated by ferrocenemonocarboxylate and 1,1'-ferrocenedicarboxylate anions: preparation, characterization and structures of trinuclear [LMII 2(O2CC5H4FeCp)]+ and Pentanuclear [(LMII 2)2(O2CC5H4)2Fe]2+ complexes (M=Co, Ni, Zn)

A series of novel tri- and pentanuclear complexes composed of dinuclear LM(2) units (M=Co, Ni, Zn; L=24-membered macrocyclic hexaazadithiophenolate ligand) and ferrocenecarboxylate ([CpFeC(5)H(4)CO(2)](-)) or 1,1'-ferrocenedicarboxylate ([Fe(C(5)H(4)CO(2))(2)](2-)) groups is reported. The complexes [LM(II) (2)(O(2)CC(5)H(4)FeCp)](+) (M=Co (6), Ni (7), Zn (8)) and [(LM(II) (2))(2)(O(2)CC(5)H(4))(2)Fe](2+) (M=Co (9), Ni (10)) have been prepared by substitution reactions from labile [LM(II) (2)L'](+) precursors (L'=Cl, OAc) and the respective ferrocenecarboxylate anions in methanol. Mixed-valent [(LCo(II)Co(III))(2)(O(2)CC(5)H(4))(2)Fe](4+) (11) was prepared by oxidation of 9 with bromine. Complexes 7[BPh(4)], 8[BPh(4)], 9[BPh(4)](2), 10[BPh(4)](2), and 11[ClO(4)](4) have been characterized by X-ray crystallography; showing that the ferrocenyl carboxylates act as bidentate (7, 8) or bis-bidentate (9-11) bridging ligands towards one or two bioctahedral LM(2) subunits, respectively. The structures are retained in solution as indicated by NMR spectroscopic studies on the diamagnetic Zn(2)Fe complex 8[ClO(4)]. Electrochemical studies reveal significant anodic potential shifts for the oxidation potential of the ferrocenyl moieties upon complexation and the magnitude of the potential shift appears to correlate with the charge of the LM(2) subunits. This is qualitatively explained in terms of destabilizing electrostatic (Coulomb) interactions between the M(2+) ions of the LM(2) unit and the proximate ferrocenium fragment. An analysis of the temperature-dependent magnetic susceptibility data for 10[BPh(4)](2) shows the presence of weak ferromagnetic magnetic exchange interactions between the Ni(II) ions in the LNi(2) units. The exchange coupling across the ferrocenedicarboxylate bridge is negligible.     

Cyclotriphosphazene hydrazides as efficient multisite coordination ligands. eta(3)-fac-non-geminal-N(3) coordination of spiro-N(3)P(3)[O(2)C(12)H(8)][N(Me)NH(2)](4) (L) in L(2)CoCl(3) and L(2)M(NO(3))(2) (M = Ni, Zn, Cd)

The cyclophosphazene tetrahydrazide spiro-N(3)P(3)[O(2)C(12)H(8)][N(Me)NH(2)](4) (L) functions as a multisite coordination ligand and affords L(2)CoCl(3).2CH(3)OH (4), L(2)Ni(NO(3))(2).2CHCl(3).2.5H(2)O (5), L(2)Zn(NO(3))(2).2CH(3)CN.2H(2)O (6), and L(2)Cd(NO(3))(2) (7). Each of the cyclophosphazene ligands that is involved in coordination to the metal functions as a non-geminal-N(3) donor coordinating through one ring nitrogen atom and two non-geminal-NH(2) nitrogen atoms. The coordination geometry around the metal ion in 4-6 is approximately octahedral while it is severely distorted in the case of 7.     

Asymmetric dinuclear copper(I) complexes of bis-(2-(2-pyridyl)ethyl)-2-(N-toluenesulfonylamino)ethylamine with short copper-copper distances

Addition of two equivalents of CuCl to deprotonated bis-(2-(2-pyridyl)ethyl)-2-(N-toluenesulfonylamino)ethylamine (PETAEA) and its derivatives yielded new types of dinuclear Cu(I) complexes, Cu(mu-PETAEA)CuCl, Cu(mu-PEMAEA)CuCl, and Cu(mu-PENAEA)CuCl (PEMAEA is the 4-methoxyphenyl derivative of PETAEA and PENAEA is the 4-nitrophenyl derivative), exhibiting a four coordinate N(4)Cu center, a two coordinate NCuCl center, and a metal-metal distance within the range of 2.6572(8) to 2.6903(3) A. Analysis of the covalent radii for four coordinate and two coordinate copper(I), the acute copper-nitrogen-copper angles, and density functional theory (DFT) calculations suggest a weak attraction between the two copper atoms. The complexes apparently formed in a two-step process with the formation of the tetracoordinate mononuclear complex preceding the coordination of a second equivalent of CuCl to the lone pair of the sulfonamidate ligand.     

Magnetic properties and molecular structures of binuclear (2-pyrazinecarboxylate)-bridged complexes containing Re(IV) and M(II) (M = Co, Ni)

Three novel Re(iv) compounds, the mononuclear complex Bu(4)N[ReBr(5)(Hpyzc)] (1) and the heterobimetallic complexes [ReBr(5)(mu-pyzc)M(dmphen)(2)].2CH(3)CN [M = Co (2), Ni (3)] (Hpyzc = 2-pyrazinecarboxylic acid, dmphen = 2,9-dimethyl-1,10-phenanthroline), have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. The structure of 1 consists of [ReBr(5)(Hpyzc)](-) complex anions and tetrabutylammonium cations, Bu(4)N(+). The Re(iv) is surrounded by five bromide anions and a N-donor Hpyzc monodentate ligand, in a distorted octahedral environment. The structures of 2 and 3 consist of dinuclear units [ReBr(5)(mu-pyzc)M(dmphen)(2)], with the metal ions linked by a pyzc bridge ligand, being bidentate toward M(II) and monodentate toward Re(IV). The environment of Re(IV) is the same as in 1, whereas M(II) is six-coordinate, being surrounded by four nitrogen atoms of two bidentate dmphen ligands and one oxygen atom and one nitrogen atom of the pyzc anion. The magnetic properties of 1-3 were investigated in the temperature range 2.0-300 K. 1 shows the expected magnetic behavior for a mononuclear Re(IV) complex with a weak intermolecular antiferromagnetic coupling at low temperatures. The bimetallic complexes exhibit an intramolecular ferromagnetic coupling between Re(IV) and the M(II) ion (Co, Ni).     

Organometallic Fluorides of Zirconium and Hafnium in the Synthesis of Carboxylate Complexes: Molecular Structures of [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] and [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)

The reaction of [(eta(5)-C(5)Me(5))ZrF(3)] and [(eta(5)-C(5)Me(5))HfF(3)] with Me(3)SiOCOCF(3) yields the dinuclear complexes [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] (1) and [{(eta(5)-C(5)Me(5))HfF(OCOCF(3))(2)}(2)] (2), regardless of the molar ratio employed. [(eta(5)-C(5)Me(5))(2)ZrF(2)] reacts with 1 and 2 equiv of Me(3)SiOCOCF(3) to form the mononuclear compounds [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)] (3) and [(eta(5)-C(5)Me(5))(2)ZrF(OCOCF(3))] (4), respectively. The molecular structures of 1 and 3 have been determined by single-crystal X-ray analysis: 1, triclinic, P&onemacr;, a = 9.508(3) ?, b = 11.002(4) ?, c = 17.528(3) ?, alpha = 78.55(4), beta = 76.80(2), gamma = 87.51(2) degrees, V = 1750(1) ?(3), Z = 2, R = 0.0378; 3, monoclinic, C2/c, a = 18.553(4) ?, b = 9.110(2) ?, c = 16.323(3) ?, beta = 114.88(3) degrees, V = 2503(1) ?(3), Z = 4, R = 0.0457. Compound 1 shows bridging bidentate and chelating carboxylate ligands as well as bridging fluorine atoms. The zirconium atoms are seven coordinated and have an 18-electron configuration. X-ray studies of 3 reveal two structural components where the carboxylate ligands coordinate in a monodentate (major component) and a chelating manner (minor component).     

Novel hetero-bimetallic metalla-macrocycles based on the bis-1-pyridyl ferrocene [Fe(eta 5-C5H(4)-1-C5H4N)2] ligand. Design,synthesis and structural characterization of the complexes [Fe(eta 5-C5H(4)-1-C5H4N)2](AgI)2(2+)/(CuII)2(4+)/(ZnII)2(4+)

The bidentate sandwich ligand [Fe(eta 5-C5H(4)-1-C5H4N)2] has been prepared, structurally characterized and employed in the preparation of the novel supramolecular heterobimetallic metalla-macrocycles [Fe(eta 5-C5H(4)-1-C5H4N)2]Ag2(NO3)(2).1.5H2O, [Fe(eta 5-C5H(4)-1-C5H4N)2]Cu2(CH3COO)(4).3H2O and [Fe(eta 5-C5H(4)-1-C5H4N)2]Zn2Cl4.     

Structural and magnetic studies of the tris(cyclopentadienyl)manganese(II) "paddle-wheel" anions [Cp(3-n)(MeCp)(n)Mn](-) (n=0-3, MeCp=C(5)H(4)CH(3), Cp=C(5)H(5))

The ion-contact complexes [{(eta(5)-Cp)(2)Mn(eta(2):eta(5)-Cp)K}(3)]x0.5 THF (1x0.5 THF) and [{(eta(2)-Cp)(2)(eta(2);eta(5)-MeCp)MnK(thf)}]x2 THF (2x2 THF) and ion-separated complexes [Mg(thf)(6)][(eta(2)-Cp)(3)Mn](2) (3), [Mg(thf)(6)][(eta(2)-Cp)(eta(2)-MeCp)(2)Mn)](2)x0.5 THF (4x0.5 THF), [Mg(thf)(6)][(eta(2)-MeCp)(3)Mn)](2)x0.5 THF (5x0.5 THF) and [Li([12]crown-4)](5)[(eta-Cp)(3)Mn](5) (6) (Cp=C(5)H(5), CpMe=C(5)H(4)CH(3)), have been prepared and structurally characterised. The effects of varying the Cp and CpMe ligands in complexes 1-5 have been probed by variable-temperature magnetic susceptibility measurements and EPR spectroscopic studies.     

Shaping and enforcing coordination spheres: the implications of C3 and C1 chirality in the coordination chemistry of 1,1,1-tris(oxazolinyl)ethane ("trisox")

A key feature of tris(oxazolinyl)ethane ("trisox") ligands, which have shown broad scope in asymmetric catalysis, is the orientation and steric demand of their oxazoline substituents. This, along with the modularity of their synthesis determines their coordination chemistry. The possibility to combine oxazolines, in which the stereogenic centers adjacent to the N-donor atoms have different absolute configuration, whilst retaining their ability to coordinate as tripodal ligands, has been demonstrated by the synthesis of the enantiomerically pure C3-symmetric iPr-trisox(S,S,S) and C1-symmetric iPr-trisox(S,S,R) and their reaction with [Mo(CO)3(NCMe)3] yielding [Mo{iPr-trisox(S,S,S)}(CO)3] (1 a) and [Mo{iPr-trisox(S,S,R)}(CO)3] (1 b), respectively. The non-autocomplementarity of two homochiral trisox ligands at one metal center has been demonstrated by reaction of rac-C3 iPr-trisox with one equivalent of [Co(ClO4)2].6 H2O, giving the centrosymmetric heterochiral complex [Co(iPr-trisox)2](ClO4)2 (3), whereas an analogous reaction with the enantiopure ligand yielded a mixture of Co(II) complexes, which is characterized by the total absence of a [(trisox)2Co](+/2+) ion. The scope of the trisox ligand in terms of facial coordination to both early and late transition metals was demonstrated by the synthesis and structural characterization of the mononuclear complexes [ScCl3(iPr-trisox)] (4), [Fe(tBu-trisox)(NCMe)3](BF4)2 (5), and [Ru(eta6-p-cymene)(iPr-trisox)](PF6)2 (6). The facial coordination of their three ligating atoms to a metal center may be impeded if the transition-metal center stereoelectronically strongly favors a non-deltahedral coordination sphere, which is generally the case for the heavier d8-transition-metal atoms/ions. Reaction of iPr-trisox with [Rh(cod)2]BF4 led to the formation of the 16-electron d8-configured complex [Rh(iPr-trisox)(cod)](BF4) (7), which is oxidized by CsBr3 to give the Rh(III) complex [RhBr3(iPr-trisox)] (8) possessing a C3-symmetric structure with a kappa3-N-trisox ligand. The crystalline salts [M2(mu-Cl3)(iPr-trisox)2](PF6) (M=Fe(II): 9, Co(II): 10, Ni(II): 11), were prepared by addition of one molar equivalent of iPr-trisox and an excess of KPF6 to solutions of the anhydrous (FeCl2) or hydrated metal halides (CoCl2.6 H2O, NiCl2.6 H2O). All dinuclear complexes display weak magnetic coupling. For the mononuclear species [CuCl2(iPr-trisox)] (12) the removal of a chloride anion and thus the generation of a dinuclear chloro-bridged structure failed due to Jahn-Teller destabilization of a potential octahedral coordination sphere.     

Coordination and oxidative addition at a low-coordinate rhodium(I) beta-diiminate centre

The reaction of 14e [L(Me)Rh(coe)] (1; L(Me)[double bond]ArNC(Me)CHC(Me)NAr, Ar[double bond]2,6-Me(2)C(6)H(3); coe[double bond]cis-cyclooctene) with phenyl halides and thiophenes was studied to assess the competition between sigma coordination, arene pi coordination and oxidative addition of a C-X bond. Whereas oxidative addition of the C-Cl and C-Br bonds of chlorobenzene and bromobenzene to L(Me)Rh results in the dinuclear species [[L(Me)Rh(Ph)(micro-X)](2)] (X=Cl, Br), fluorobenzene yields the dinuclear inverse sandwich complex [[L(Me)Rh](2)(anti-micro-eta(4):eta(4)-PhF)]. Thiophene undergoes oxidative addition of the C-S bond to give a dinuclear product. The reaction of 1 with dibenzo[b,d]thiophene (dbt) in the ratio 1:2 resulted in the formation of the sigma complex [L(Me)Rh(eta(1)-(S)-dbt)(2)], which in solution dissociates into free dbt and a mixture of the mononuclear complex [L(Me)Rh(eta(4)-(1,2,3,4)-dbt)] and the dinuclear complex [[L(Me)Rh](2)(micro-eta(4)-(1,2,3,4):eta(4)-(6,7,8,9)-dbt)]. The latter could be obtained selectively by the 2:1 reaction of 1 and dbt. Reaction of 1 with diethyl sulfide produces [L(Me)Rh(Et(2)S)(2)], which in the presence of hydrogen loses a diethyl sulfide ligand to give [L(Me)Rh(Et(2)S)(H(2))] and catalyses the hydrogenation of cyclooctene.     

Rational assembly of soluble copper(II) phosphonates: synthesis, structure and magnetism of molecular tetranuclear copper(II) phosphonates

The reactions of the dinuclear copper complexes [Cu(2)(L)(OAc)] [H(3)L = N,N'-(2-hydroxypropane-1,3-diyl)bis(salicylaldimine) or [Cu(2)(L')(OAc)] (H(3)L' = N,N'-(2-hydroxypropane-1,3-diyl)bis(4,5-dimethylsalicylaldimine)] with various phosphonic acids, RPO(3)H(2) (R = t-Bu, Ph, c-C(5)H(9), c-C(6)H(11) or 2,4,6-i-Pr(3)-C(6)H(2)), leads to the replacement of the acetate bridge affording tetranuclear copper(II) phosphonates, [Cu(4)(L)(2)(t-BuPO(3))](CH(3)OH)(2)(C(6)H(6)) (1), [Cu(4)(L)(2)(PhPO(3))(H(2)O)(2)(NMe(2)CHO)](H(2)O)(2) (2), [Cu(4)(L')(2)(C(5)H(9)PO(3))](CH(3)OH)(2) (3), [Cu(4)(L')(2)(C(6)H(11)PO(3)](MeOH)(4)(H(2)O)(2) (4) and [Cu(4)(L')(2)(C(30)H(46)P(2)O(5))](PhCH(3)) (5). The molecular structures of 1-4 reveal that a [RPO(3)](2-) ligand is involved in holding the four copper atoms together by a 4.211 coordination mode. In 5, an in situ formed [(RPO(2))(2)O](4-) ligand bridges two pairs of the dinuclear subunits. Magnetic studies on these complexes reveal that the phosphonate ligand is an effective conduit for magnetic interaction among the four copper centers present; a predominantly antiferromagnetic interaction is observed at low temperatures.     

Cobalt(II), nickel(II), copper(II), and zinc(II) complexes with [3(5)]adamanzane, 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane, and [(2.3)(2).2(1)] adamanzane, 1,5,9,12-tetraazabicyclo[7.5.2]hexadecane

Isolation of the free bicyclic tetraamine, [3(5)]adamanzane.H(2)O (1,5,9,13-tetraazabicyclo[7.7.3]nonadecane.H(2)O), is reported along with the synthesis and characterization of a copper(II) complex of the smaller macrocycle [(2.3)(2).2(1)]adamanzane (1,5,9,12-tetraazabicyclo[7.5.2]hexadecane) and of three cobalt(II), four nickel(II), one copper(II), and two zinc(II) complexes with [3(5)]adamanzane. For nine of these compounds (2-8, 10b, and 12) the single-crystal X-ray structures were determined. The coordination geometry around the metal ion is square pyramidal in [Cu([(2.3)(2).2(1)]adz)Br]ClO(4) (2) and trigonal bipyramidal in the isostructural structures [Cu([3(5)]adz)Br]Br (3), [Ni([3(5)]adz)Cl]Cl (5), [Ni([3(5)]adz)Br]Br (6), and [Co([3(5)]adz)Cl]Cl (8). In [Ni([3(5)]adz)(NO(3))]NO(3) (4) and [Ni([3(5)]adz)(ClO(4))]ClO(4) (7) the coordination geometry around nickel(II) is a distorted octahedron with the inorganic ligands at cis positions. The coordination polyhedron around the metal ion in [Co([3(5)]adz)][ZnCl(4)] (10b) and [Zn([3(5)]adz)][ZnCl(4)] (12) is a slightly distorted tetrahedron. Anation equilibrium constants were determined spectrophotometrically for complexes 2-6 at 25 and 40 degrees C and fall in the region 2-10 M(-1) for the halide complexes and 30-65 M(-1) for the nickel(II) nitrate complex (4). Rate constants for the dissociation of the macrocyclic ligand from the metal ions in 5 M HCl were determined for complexes 2, 3, 5, 8, 10, and 12. The reaction rates vary from half-lives at 40 degrees C of 14 min for the dissociation of the Zn([3(5)]adz)(2+) complex (12) to 14-15 months for the Ni([3(5)]adz)Cl(+) ion (5).     

Synthesis of the new, cubane-like W3S4Co cluster core. Completion of the homologous series [(eta5-Cp')3M3S4Co(CO)] (M = Cr, Mo, W)

Reaction between the cluster salts [(eta(5)-Cp')(3)M(3)S(4)][pts] (M = Mo, W; Cp' = methylcyclopentadienyl; pts = p-toluenesulfonate) and [Co(2)(CO)(8)] yielded the electroneutral clusters [(eta(5)-Cp')(3)M(3)S(4)Co(CO)]. The molecular structure of [(eta(5)-Cp')(3)W(3)S(4)Co(CO)] was determined by single-crystal X-ray diffraction methods. The unprecedented 60 electron W(3)S(4)Co cluster completes a homologous series of heterobimetallic clusters, [(eta(5)-Cp')(3)M(3)S(4)Co(CO)] (M = Cr, Mo, W), containing a cubane-like core motif.     

Copper(I) complexes of tripodal tris(imidazolyl) ligands: potential mimics of the Cu(A) site of hydroxylase enzymes

Copper(I) complexes of tripodal tris(N-methyl-4,5-diphenyl-imidazolyl)methane ligands, N3CR (1a-c, R = OH, OMe, H), have been prepared as models for the Cu(A) site of copper hydroxylase enzymes. In the absence of additional donors, the ligands 1 react with [Cu(CH3CN)4]PF6 (2) to produce dinuclear complexes [(N3CR)2Cu2](PF6)2 (3) in which the tripodal ligands bridge two trigonal Cu centers; the structures of 3b and 3c are established by X-ray diffraction. Mononuclear adducts [(N3CR)CuL]Z are produced with L = acetonitrile (4), carbon monoxide (5), and t-BuNC (6, 7). The carbonyl complexes 5 are in dynamic equilibrium with the dimeric complexes 3, but 5c (R = H) can be isolated. The structures of the isocyanide derivatives depend critically on the tripod methane substituent, R. Thus, the X-ray structures of 6 (R = OMe) and 7 (R = H) show trigonal and tetrahedral geometries, respectively, with bi- or tridentate coordination of the tripod. A trinuclear complex [Cu3(N3COH)2(t-BuNC)2](PF6)3 (8) is formed from N3COH (1a) which features both three-coordinate and two-coordinate Cu atoms and bidentate tripod coordination. Reactions of dioxygen with dinuclear 3c or mononuclear [(N3CR)CuL]Z are sluggish, producing from the latter in acetone [(N3CH)CuII(L)(L')](PF6)2 (9, L = acetone, L' = H2O).     

Reduction of an eta2-iminoacyl ligand to eta2-iminium enabled by adjacent carbon monoxide ligand replacement with a variable electron donor alkyne ligand in a cationic Tungsten(II) bis(acetylacetonate) complex

Cationic iminoacyl-carbonyl tungsten complexes of the type [W(CO) (eta (2)-MeNCR)(acac) 2] (+) (acac = acetylacetonate; R = Ph ( 1a), Me ( 1b)) easily undergo thermal substitution of CO with two-electron donors to yield [W(L)(eta (2)-MeNCR)(acac) 2] (+) (L = tert-butylisonitrile [R = Ph ( 2a), Me ( 2b)], 2,6-dimethylphenylisonitrile [R = Me ( 2c)], triphenylphosphine [R = Ph ( 3a), Me ( 3c)], and tricyclohexylphosphine [R = Ph ( 3b)]). Tricyclohexylphosphine complex 3b exhibits rapid, reversible phosphine ligand exchange at room temperature on the NMR time scale. Photolytic replacement of carbon monoxide with either phenylacetylene or 2-butyne occurs efficiently to form [W(eta (2)-alkyne)(eta (2)-MeNCR)(acac) 2] (+) complexes ( 5a- d) with a variable electron donor eta (2)-alkyne paired with the eta (2)-iminoacyl ligand in the W(II) coordination sphere. PMe 3 adds to 1a or 5b to form [W(L)(eta (2)-MeNC(PMe 3)Ph)(acac) 2] (+) [L = CO ( 4), MeCCMe ( 6)] via nucleophilic attack at the iminoacyl carbon. Addition of Na[HB(OMe) 3] to 5b yields W(eta (2)-MeCCMe)(eta (2)-MeNCHPh)(acac) 2, 8, which exhibits alkyne rotation on the NMR time scale. Addition of MeOTf to 8 places a second methyl group on the nitrogen atom to form an unusual cationic eta (2)-iminium complex [W(eta (2)-MeCCMe)(eta (2)-Me 2NCHPh)(acac) 2][OTf] ( 9[OTf], OTf = SO 3CF 3). X-ray structures of 2,6-dimethylphenylisonitrile complex 2c[BAr' 4 ], tricyclohexylphosphine complex 3b[BAr' 4 ], and phenylacetylene complex 5a[BAr' 4 ] confirm replacement of CO by these ligands in the [W(L)(eta (2)-MeNCR)(acac) 2] (+) products. X-ray structures of alkyne-imine complexes 6[BAr' 4 ] and 8 show products resulting from nucleophilic addition at the iminoacyl carbon, and the X-ray structure of 9[BAr' 4 ] reflects methylation at the imine nitrogen to form a rare eta (2)-iminium ligand.     

Syntheses and structures of three complexes of formulas [L3Co(μ2-O2P(Bn)2)3CoL'][L"], featuring octahedral and tetrahedral cobalt(II) geometries; variable-temperature magnetic susceptibility measurement and analysis on [(py)3Co(μ2-O2PBn2)3Co(py)][ClO4

The syntheses and structural properties of three dinuclear complexes [L(3)Co(μ(2)-O(2)P(Bn)(2))(3)CoL'][L"] [one ionic L(3) = py(3), L' = py, L" = ClO(4)(-) (1) and two molecular L(3) = py(3), L' = Cl (2) and L(3) = py, μ(2)-NO(3)(-), L' = py (3)] are reported. Complexes feature octahedral Co(II) sites bridged by three dibenzylphosphinate ligands to a tetrahedrally ligated Co(II) site, with the remaining coordination sites occupied by py, nitrato, and Cl ligands. The Co-Co distances are 4.248 ? at 291 K and 4.265 ? at 100 K for 1 and 4.278 and 4.0313(7) ? for 2 and 3, respectively at 100 K. A fit of the low-temperature magnetic susceptibility data was derived for complex 1 with g = 2.25, TIP = 700 × 10(-6) cm(3) mol (-1), λ = -173 cm(-1), κ = 0.93, ν = -3.9, Δ = 630 cm(-1), J = 0.15 cm(-1), and θ = -1.8 resulting in R(χ(M)) = 2.5 × 10(-5) and R(χ(M)T) = 5.8 × 10(-5).     

Collision-induced dissociation of MCl(+) adducts (M = Mg, Mn, Zn, Co, Ni and Cu) and Cu(+) and Ag(+) adducts of dithioalkyl ketene acetals

Electrospray ionization mass spectra of equimolar solutions of dithioalkyl ketene acetals 1 and 2 and metal chlorides (MgCl(2), MnCl(2), ZnCl(2), CoCl(2), NiCl(2) and CuCl(2)) produced abundant ligated metal ion adducts [1 + MCl](+) and [2 + MCl](+). In addition, CuCl(2) also gave rise to Cu(+) adducts. The ligated metal ion adducts upon collision-induced dissociation (CID) showed characteristic fragmentation pathways reflecting the favoured site of coordination. The results show that MgCl(+) prefers oxygen over sulfur, whereas the reverse is true for ZnCl(+) adducts, exemplified by the preferred fragmentation of [1 + MgCl](+) as elimination of MgCl(OH), while that of [1 + ZnCl](+) is expulsion of ZnCl(SCH(3)). Co and Ni chloride adducts tend to give stable metal coordinated species. Cleavage of the dithiolane ring followed by elimination of C(2)H(4)S is the preferred pathway during the CID of [2 + MCl](+) adducts. The CuCl(+) adducts of 1 and 2 showed reduction of Cu((I)) to Cu((0)) resulting in the M(+)(*)ions of 1 and 2. Abstraction of *CH(3) resulting in elimination of CuCH(3) was observed during CID of Cu(+) adducts of 1 and 2. A comparative study of the corresponding Ag(+) adducts revealed a similar behaviour.