Perturbation of the Electronic Structure of a Copper(II) ion by a Cu(I)Cl Moiety in a Class I Mixed Valence Copper Complex, Cu(II)(Me(5)dien)Cl(2)(Cu(I)Cl)

A new mixed valence copper complex Cu(II)(Me(5)dien)Cl(2)(Cu(I)Cl) (2) was obtained from the reaction of CuCl with Cu(II)(Me(5)dien)Cl(2) (1) in acetonitrile. The structures of 1 and 2 have been determined by single-crystal X-ray diffraction analyses. Compound 1 crystallizes in the monoclinic space group P2(1)/n with a = 8.374(5) ?, b = 17.155(3) ?, c = 23.806(5) ?, beta = 94.40(4) degrees, Z = 8, and V = 3398(1) ?(3) while compound 2 crystallizes in orthorhombic space group Pbcn with a = 14.71(1) ?, b = 16.06(2) ?, c = 13.38(1) ?, Z = 8, and V = 3159(5) ?. The Cu(II)(Me(5)dien)Cl(2) unit in both compounds has a similar distorted square-pyramidal geometry. The Cu(I)Cl moiety in 2 is attached to the Cu(II) unit via two bridging chlorine atoms and has a distorted trigonal planar geometry. UV-vis and EPR spectroscopic studies and molecular orbital calculations established the presence of significant perturbation of the Cu(I)Cl unit to the electronic structure of the Cu(II) ion in compound 2.     

Copper and Bismuth Complexes Containing Dipyridyl gem-Diolato Ligands: Bi(III)(2)[(2-Py)(2)CO(OH)](2)(O(2)CCF(3))(4)(THF)(2), Cu(II)[(2-Py)(2)CO(OH)](2)(HO(2)CCH(3))(2), and Cu(II)(4)[(2-Py)(2)CO(OH)](2)(O(2)CCH(3))(6)(H(2)O)(2), a Ferromagnetically Coupled Tetranuclear Copper(II) Chain

The reactions of the singly deprotonated di-2-pyridylmethanediol ligand (dpmdH(-)) with copper(II) and bismuth(III) have been investigated. A new dinuclear bismuth(III) complex Bi(2)(dpmdH)(2)(O(2)CCF(3))(4)(THF)(2), 1, has been obtained by the reaction of BiPh(3) with di-2-pyridyl ketone in the presence of HO(2)CCF(3) in tetrahydrofuran (THF). The reaction of Cu(OCH(3))(2) with di-2-pyridyl ketone, H(2)O, and acetic acid in a 1:2:2:2 ratio yielded a mononuclear complex Cu[(2-Py)(2)CO(OH)](2)(HO(2)CCH(3))(2), 2, while the reaction of Cu(OAC)(2)(H(2)O) with di-2-pyridyl ketone and acetic acid in a 2:1:1 ratio yielded a tetranuclear complex Cu(4)[(2-Py)(2)CO(OH)](2)(O(2)CCH(3))(6)(H(2)O)(2), 3. The structures of these complexes were determined by single-crystal X-ray diffraction analyses. Three different bonding modes of the dpmdH(-) ligand were observed in compounds 1-3. In 2, the dpmdH(-) ligand functions as a tridentate chelate to the copper center and forms a hydrogen bond between the OH group and the noncoordinating HO(2)CCH(3) molecule. In 1 and 3, the dpmdH(-) ligand functions as a bridging ligand to two metal centers through the oxygen atom. The two pyridyl groups of the dpmdH(-) ligand are bound to one bismuth(III) center in 1, while in 3 they are bound two copper(II) centers, respectively. Compound 3 has an unusual one dimensional hydrogen bonded extended structure. The intramolecular magnetic interaction in 3 has been found to be dominated by ferromagnetism. Crystal data: 1, C(38)H(34)N(4)O(14)F(12)Bi(2), triclinic P&onemacr;, a = 11.764(3) ?, b = 11.949(3) ?, c = 9.737(1) ?, alpha =101.36(2) degrees, beta = 105.64(2) degrees, gamma = 63.79(2) degrees, Z = 1; 2, C(26)H(26)N(4)O(8)Cu/CH(2)Cl(2), monoclinic C2/c, a = 25.51(3) ?, b = 7.861(7) ?, c = 16.24(2) ?, beta = 113.08(9) degrees, Z = 4; 3, C(34)H(40)N(4)O(18)Cu(4)/CH(2)Cl(2), triclinic P&onemacr;, a = 10.494(2) ?, b = 13.885(2) ?, c = 7.900(4) ?, alpha =106.52(2) degrees, beta = 90.85(3) degrees, gamma = 94.12(1) degrees, Z = 1.     

Syntheses and Crystal Structures of Ruthenium Complexes of 1,4,8,11-Tetraazacyclotetradecane, Tris(2-aminoethyl)amine (tren), and Bis(2-aminoethyl)(iminomethyl)amine. A Microporous Layered Structure Consisting of {[K(tren)](2)[RuCl(6)]}(n)()(n)()(-) and {(H(5)O(2))(4)[RuCl(6)]}(n)()(n)()(+)

The second method for the synthesis of cis-[Ru(III)Cl(2)(cyclam)]Cl (1) (cyclam = 1,4,8,11-tetraazacyclotetradecane), with use of cis-Ru(II)Cl(2)(DMSO)(4) (DMSO = dimethyl sulfoxide) as a starting complex, is reported together with the synthesis of [Ru(II)(cyclam)(bpy)](BF(4))(2).H(2)O (2) (bpy = 2,2'-bipyridine) from 1. The syntheses of Ru complexes of tris(2-aminoethyl)amine (tren) are also reported. A reaction between K(3)[Ru(III)(ox)(3)] (ox = oxalate) and tren affords fac-[Ru(III)Cl(3)(trenH)]Cl.(1)/(2)H(2)O (3) (trenH = bis(2-aminoethyl)(2-ammonioethyl)amine = monoprotonated tren) and (H(5)O(2))(2)[K(tren)][Ru(III)Cl(6)] (4) as major products and gives fac-[Ru(III)Cl(ox)(trenH)]Cl.(3)/(2)H(2)O (5) in very low reproducibility. A reaction between 3 and bpy affords [Ru(II)(baia)(bpy)](BF(4))(2) (6) (baia = bis(2-aminoethyl)(iminomethyl)amine), in which tren undergoes a selective dehydrogenation into baia. The crystal structures of 2-6 have been determined by X-ray diffraction, and their structural features are discussed in detail. Crystallographic data are as follows: 2, RuF(8)ON(6)C(20)B(2)H(34), monoclinic, space group P2(1)/c with a = 12.448(3) ?, b = 13.200(7) ?, c = 17.973(4) ?, beta = 104.28(2) degrees, V = 2862(2) ?(3), and Z = 4; 3, RuCl(4)O(0.5)N(4)C(6)H(20), monoclinic, space group P2(1)/a with a = 13.731(2) ?, b = 14.319(4) ?, c = 13.949(2) ?, beta = 90.77(1) degrees, V = 2742(1) ?(3), and Z = 8; 4, RuKCl(6)O(4)N(4)C(6)H(28), trigonal, space group R&thremacr; with a = 10.254(4), c = 35.03(1) ?, V = 3190(2) ?(3), and Z = 6; 5, RuCl(2)O(5.5)N(4)C(8)H(22), triclinic, space group P&onemacr; with a = 10.336(2) ?, b = 14.835(2) ?, c = 10.234(1) ?, alpha = 90.28(1) degrees, beta = 90.99(1) degrees, gamma = 92.07(1) degrees, V = 1567.9(4) ?(3), and Z = 4; 6, RuF(8)N(6)C(16)B(2)H(24), monoclinic, space group P2(1)/c, a = 10.779(2) ?, b = 14.416(3) ?, c = 14.190(2) ?, beta = 93.75(2) degrees, V = 2200.3(7) ?(3), and Z = 4. Compound 4 possesses a very unique layered structure made up of both anionic and cationic slabs, {[K(tren)](2)[Ru(III)Cl(6)]}(n)()(n)()(-) and {(H(5)O(2))(4)[Ru(III)Cl(6)]}(n)()(n)()(+) (n = infinity), in which both sheets {[K(tren)](2)}(n)()(2)(n)()(+) and {(H(5)O(2))(4)}(n)()(4)(n)()(+) offer cylindrical pores that are occupied with the [Ru(III)Cl(6)](3)(-) anions. The presence of a C=N double bond of baia in 6 is judged from the C-N distance of 1.28(2) ?. It is suggested that the structural restraint enhanced by the attachment of alkylene chelates at the nitrogen donors of amines results in either the mislocation or misdirection of the donors, leading to the elongation of the Ru-N(amine) distances and to the weakening of their trans influence. Such structural strain is also discussed as related to the spectroscopic and electrochemical properties of the cis-[Ru(II)L(4)(bpy)](2+) complexes (L(4) = (NH(3))(4), (ethylenediamine)(2), and cyclam).     

Polyoxometalate Derivatives with Multiple Organic Groups. 3. Synthesis and Structure of Bis(phenyltin) Bis(decatungstosilicate), [(PhSnOH(2))(2)(gamma-SiW(10)O(36))(2)](10)(-)

A new phenyltin tungstosilicate derivative, [(PhSnOH(2))(2)(gamma-SiW(10)O(36))(2)](10)(-) (1), has been prepared by reaction of phenyltin trichloride with K(8)[gamma-SiW(10)O(36)].xH(2)O. The new heteropolyanion was characterized by elemental analysis, infrared spectroscopy, multinuclear NMR, and X-ray crystallography. The crystals of Cs(9)H[(PhSnOH(2))(2)(gamma-SiW(10)O(36))(2)].16H(2)O (Cs salt of 1) are triclinic, space group P&onemacr;, with lattice constants a = 12.401(3) ?, b = 13.832(3) ?, c = 16.313(3) ?, alpha = 96.17(2) degrees, beta = 109.73(2) degrees, gamma = 97.13(2) degrees, V = 2579.9(10) ?, and Z = 1. Anion 1 has a structure of virtual C(2)(h)() symmetry with two phenyltin groups sandwiched between two gamma-SiW(10) groups. Such a structure is different from all previously reported polytungstates derived from [gamma-SiW(10)O(36)](8)(-) lacunary anions.     

Monomeric Bis(eta(2)-alkyne)copper(I) and -silver(I) Halides, Pseudohalides, and Arenethiolates

The synthesis and characterization of the complexes [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]MX (M = Cu, X = OTf (2), SC(6)H(5) (4), SC(6)H(4)NMe(2)-2 (5), SC(6)H(4)CH(2)NMe(2)-2 (6), S-1-C(10)H(6)NMe(2)-8 (7), Cl (8), (N&tbd1;CMe)PF(6) (9); M = Ag, X = OTf (3)) are described. These complexes contain monomeric MX entities, which are eta(2)-bonded by both alkyne functionalities of the organometallic bis(alkyne) ligand [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)] (1). The reactions of 2 with the Lewis bases N&tbd1;CPh and N&tbd1;CC(H)=C(H)C&tbd1;N afford the cationic complexes {[(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]Cu(N&tbd1;CPh)}OTf (10) and {[(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]Cu}(2)(N&tbd1;CC(H)=C(H)C&tbd1;N)(OTf)(2) (11), respectively. The X-ray structures of 2, 3, and 6 have been determined. Crystals of 2 are monoclinic, space group P2(1)/c, with a = 12.8547(7) ?, b = 21.340(2) ?, c = 18.279(1) ?, beta = 133.623(5) degrees, V= 3629.7(5) ?(3), Z = 4, and final R = 0.047 for 5531 reflections with I >/= 2.5sigma(I) and 400 variables. The silver triflate complex 3 is isostructural, but not isomorphous, with the corresponding copper complex 2, and crystals of 3 are monoclinic, space group P2(1)/c, with a = 13.384(3) ?, b = 24.55(1) ?, c = 13.506(3) ?, beta = 119.21(2) degrees, V = 3873(2) ?(3), Z = 4, and final R = 0.038 for 3578 reflections with F >/= 4sigma(F) and 403 variables. Crystals of the copper arenethiolate complex 6 are triclinic, space group P&onemacr;, with a = 11.277(3) ?, b = 12.991(6) ?, c = 15.390(6) ?, alpha = 65.17(4) degrees, beta = 78.91(3) degrees, gamma = 84.78(3) degrees, V = 2008(2) ?(3), Z = 2, and final R = 0.079 for 6022 reflections and 388 variables. Complexes 2-11 all contain a monomeric bis(eta(2)-alkyne)M(eta(1)-X) unit (M = Cu, Ag) in which the group 11 metal atom is trigonally coordinated by the chelating bis(eta(2)-alkyne) entity Ti(C&tbd1;CSiMe(3))(2) and an eta(1)-bonded monoanionic ligand X. The copper arenethiolate complexes 4-7 are fluxional in solution.     

Synthesis and Characterization of Copper(II), Zinc(II), and Potassium Complexes of a Highly Fluorinated Bis(pyrazolyl)borate Ligand

Highly fluorinated, dihydridobis(3,5-bis(trifluoromethyl)pyrazolyl)borate ligand, [H(2)B(3,5-(CF(3))(2)Pz)(2)](-) has been synthesized and characterized as its potassium salt. The copper(II) and zinc(II) complexes, [H(2)B(3,5-(CF(3))(2)Pz)(2)](2)Cu and [H(2)B(3,5-(CF(3))(2)Pz)(2)](2)Zn, have been prepared by metathesis of [H(2)B(3,5-(CF(3))(2)Pz)(2)]K with Cu(OTf)(2) and Zn(OTf)(2), respectively. All the new metal adducts have been characterized by X-ray diffraction. The potassium salt is polymeric and shows several K.F interactions. The Cu center of [H(2)B(3,5-(CF(3))(2)Pz)(2)](2)Cu adopts a square planar geometry, whereas the Zn atom in [H(2)B(3,5-(CF(3))(2)Pz)(2)](2)Zn displays a tetrahedral coordination. Bis(pyrazolyl)borate ligands in the Zn adduct show a significantly distorted boat conformation. The nature and extent of this distortion is similar to that observed for the methylated analog, [H(2)B(3,5-(CH(3))(2)Pz)(2)](2)Zn. This ligand allows a comparison of electronic effects of bis(pyrazolyl)borate ligands with similar steric properties. Crystallographic data for [H(2)B(3,5-(CF(3))(2)Pz)(2)]K: triclinic, space group P&onemacr;, with a = 8.385(1) ?, b = 10.097(2) ?, c = 10.317(1) ?, alpha = 104.193(9) degrees, beta = 104.366(6) degrees, gamma = 91.733(9) degrees, V = 816.5(3) ?(3), and Z = 2. [H(2)B(3,5-(CF(3))(2)Pz)(2)](2)Cu is monoclinic, space group C2/c with a = 25.632(3) ?, b = 9.197(1) ?, c = 17.342(2) ?, beta = 129.292(5) degrees, V = 3164.0(6) ?(3), and Z = 4. [H(2)B(3,5-(CF(3))(2)Pz)(2)](2)Zn is triclinic, space group P&onemacr;, with a = 9.104(1) ?, b = 9.278(1) ?, c = 18.700(2) ?, alpha = 83.560(6) degrees, beta = 88.200(10) degrees, gamma = 78.637(9) degrees, V = 1538.8(3) ?(3), and Z = 2. [H(2)B(3,5-(CH(3))(2)Pz)(2)](2)Zn is monoclinic, space group C2/c with a = 8.445(1) ?, b = 14.514(2) ?, c = 19.983(3) ?, beta = 90.831(8) degrees, V = 2449.1(6) ?(3), and Z = 4.     

Synthesis and Characterization of a New Quasi-One-Dimensional Copper(II) Phosphate, Ba(2)Cu(PO(4))(2)

Crystals of Ba(2)Cu(PO(4))(2) have been grown in a low-temperature eutectic flux of 32% KCl and 68% CuCl (mp = 140 degrees C). The X-ray single-crystal structure analysis shows that this barium copper(II) phosphate crystallizes in a monoclinic lattice with a = 12.160(4) ?, b = 5.133(4) ?, c = 6.885(4) ?, beta = 105.42(4) degrees, and V = 414.3(4) ?(3); C2/m (No. 12); Z = 2. The structure has been refined by the least-squares method to a final solution with R = 0.020, R(w) = 0.026, and GOF = 1.05. The framework of the title compound consists of [Cu(PO(4))(2)](infinity) linear chains with Ba(2+) cations residing between these parallel chains. The chains are composed of an array of Cu(2+) cations that are doubly bridged by PO(4) anions. Each pair of bridging PO(4) tetrahedra are in a staggered configuration above and below the CuO(4) square plane, resulting in a linear chain with a long Cu---Cu separation distance, 5.13 ? ( identical withb). This quasi-one-dimensional framework is unusual among the Cu(2+)-based phosphates. Magnetic susceptibility data shows Curie-Weiss paramagnetic behavior in the range of ca. 190-300 K and a possible antiferro-to-ferromagnetic transition at approximately 8 K. In this paper, the synthesis, structure, and properties of the title compound are presented. A structural comparison to a closely related vanadyl (VO)(2+) phosphate, Ba(2)(VO)(PO(4))(2).H(2)O, as well as Na(2)CuP(2)O(7) will be discussed.     

The Uracil C(5) Position as a Metal Binding Site: Solution and X-ray Crystal Structure Studies of Pt(II) and Hg(II) Compounds

1,3-Dimethyluracil (1,3-DimeU) reacts with trans-[(CH(3)NH(2))(2)Pt(H(2)O)(2)](+) to give trans-[(CH(3)NH(2))(2)Pt(1,3-DimeU-C5)(H(2)O)]X (X = NO(3)(-), 1a, ClO(4)(-), 1b) and subsequently with NaCl to give trans-(CH(3)NH(2))(2)Pt(1,3-DimeU-C5)Cl (2) or with NH(3) to yield trans-[(CH(3)NH(2))(2)Pt(1,3-DimeU-C5)(NH(3))]ClO(4) (3). In a similar way, (dien)Pt(II) forms [dienPt(1,3-DimeU-C5)](+) (4). Reactions leading to formation of 1 and 4 are slow, taking days. In contrast, Hg(CH(3)COO)(2) reacts fast with 1,3-DimeU to give (1,3-DimeU-C5)Hg(CH(3)COO) (5). Both 1-methyluracil (1-MeUH) and uridine (urdH) react with (dien)Pt(II) initially at N(3) and subsequently with either (dien)Pt(II) or Hg(CH(3)COO)(2) also at C(5) to give the diplatinated species 7 and 9 or the mixed PtHg complex 8. C(5) binding of either Pt(II) or Hg(II) is evident from coupling of uracil-H(6) with either (195)Pt or (199)Hg nuclei and (3)J values of 47-74 Hz (for Pt compounds) and 185-197 Hz (for Hg compounds). J values of Pt compounds are influenced both by the ligands trans to the uracil C(5) position and by the number of metal entities bound to a uracil ring. Both 2 and 5 were X-ray structurally characterized. 2: monoclinic system, space group P2(1)/c, a = 15.736(6) ?, b = 11.481(6) ?, c = 25.655 (10) ?, beta = 145.55(3) degrees, V = 2621.9(28) ?(3), Z = 4. 5: monoclinic system, space group P2(1)/c, a = 4.905(2) ?, b = 18.451(6) ?, c = 11.801(5) ?, beta = 94.47(3) degrees, V = 1064.77(72) ?(3), Z = 4.     

Anisotropic Exchange Effects in Temperature and Pressure Dependences of EPR Zero-Field Splitting in [(C(6)H(5))(3)(n-propyl)P](2)Cu(2)Cl(6)

X-band single-crystal and powder EPR data were collected in the temperature range 4.2-300 K and under hydrostatic pressure up to 500 MPa for [(C(6)H(5))(3)(n-propyl)P](2)Cu(2)Cl(6) (C(42)H(44)P(2)Cu(2)Cl(6)). The crystal and molecular structure have been determined from X-ray diffraction. The compound crystallizes in the monoclinic space group P2(1)/n (Z = 2) and have unit cell dimensions of a = 9.556(5) ?, b= 17.113(3) ?, c = 13.523(7) ?, and beta = 96.10(4) degrees. The structure consists of two controsymmetric Cu(2)Cl(6)(2)(-) dimers well separated by complex anions. EPR spectra are typical for the triplet S = 1 state of Cu(2)Cl(6)(2)(-) dimer with parameters g(x)() = 2.114(8), g(y)() = 2.095(8), g(z)() = 2.300(8), and D(x)() = 0.025(1) cm(-)(1), D(y)() = 0.057(1) cm(-)(1), and D(z)() = -0.082(1) cm(-)(1) at room temperature. The D tensor is dominated by a contribution from anisotropic exchange but the dipole-dipole Cu-Cu coupling is not much less. The anisotropic exchange integrals were estimated to be as follows: J(xy,x)()()2(-)(y)()()2(an) = -45 cm(-)(1), J(xy,xy)()(an) = +17 cm(-)(1), J(xy,yz)()(an) = +62 cm(-)(1). The D tensor components are strongly temperature dependent and linearly increase on cooling with an anomalous nonlinear behavior below 100 K. The D values increase linearly with pressure, but the effect is much smaller than the temperature effect. This suggests that the D vs T dependence is dynamical in origin. EPR data, a possible mechanism, and contributions to the observed dependences are discussed and compared to EPR results for similar compounds.     

Molecular Assemblies Containing Unsupported [Fe(III)-(&mgr;(2):eta(2)-RCO(2))-Cu(II)] Bridges

Formate is an inhibitor of cytochrome oxidases and also effects conversion of the bovine heart enzyme from the "fast" to the "slow" cyanide-binding form. The molecular basis of these effects is unknown; one possibility is that formate inserts as a bridge into the binuclear heme a(3)-Cu(B) site, impeding the binding of dioxygen or cyanide. Consequently, Fe-Cu-carboxylate interactions are a matter of current interest. We have initiated an examination of such interactions by the synthesis of the first examples of [Fe(III)-(&mgr;(2):eta(2)-RCO(2))-Cu(II)] bridges, minimally represented by Fe(III)-L + Cu(II)-O(2)CR --> [Fe(III)-(RCO(2))-Cu(II)] + L. A series of Cu(II) precursor complexes and solvate forms have been prepared and their structures determined, including [Cu(Me(5)dien)(O(2)CH)](+) (3), [Cu(Me(5)dien)(O(2)CH)(MeOH)](+) (4), [Cu(Me(6)tren)(O(2)CH)](+) (5), and [Cu(Me(5)dien)(OAc)](+) (6). [4](ClO(4)) was obtained in monoclinic space group P2(1)/n with a = 8.166(3) ?, b = 15.119(5) ?, c = 15.070(4) ?, beta = 104.65(2) degrees, and Z = 4. [5](ClO(4))/[6](ClO(4)) crystallize in orthorhombic space groups Pnma/Pna2(1) with a = 16.788(2)/14.928(5) ?, b = 9.542(1)/9.341(4) ?, c = 12.911(1)/12.554(4) ?, and Z = 4/4. In all cases, the carboxylate ligand is terminal and is bound in a syn orientation. Also prepared for the purpose of structural comparison was [Fe(OEP)(O(2)CH)], which occurred in monoclinic space group P2(1)/c with a = 13.342(2) ?, b = 13.621(2) ?, c = 19.333(2) ?, beta = 106.12(2) degrees, and Z = 4. The desired bridges were stabilized in the assemblies [(OEP)Fe(O(2)CH)Cu(Me(5)dien)(OClO(3))](+) (9), [(OEP)Fe(OAc)Cu(Me(5)dien)](2+) (10), and {(OEP)Fe[(O(2)CH)Cu(Me(6)tren)](2)}(3+) (11), which were prepared by the reaction of 3, 6, and 5, respectively, with [Fe(OEP)(OClO(3))] in acetone or dichloromethane. [9](ClO(4))/[10](ClO(4))(2).CH(2)Cl(2) crystallize in triclinic space group P&onemacr; with a = 9.016(3)/13.777(3) ?, b = 15.377(5)/13.847(3) ?, c = 19.253(5)/17.608(4) ?, alpha = 78.12(3)/96.82(3) degrees, beta = 86.30(4)/108.06(3) degrees, gamma = 76.23(3)/114.32(3) degrees, and Z = 2/2. Each assembly contains a [Fe(III)-(RCO(2))-Cu(II)] bridge but with the differing orientations anti-anti (9) and syn-anti (10, 11). The compound [11](ClO(4))(2)(SbF(6)) occurs in orthorhombic space group Pbcn with a = 12.517(6) ?, b = 29.45(1) ?, c = 21.569(8) ?, and Z = 4. Complex 11 is trinuclear; the Fe(III) site has two axial formate ligands with bond distances indicative of a high-spin configuration. Structural features of 9-11 are discussed and are considered in relation to the possible insertion of formate into the binuclear sites of two oxidases whose structures were recently determined. The present results contribute to the series of molecular assemblies with the bridge groups [Fe(III)-X-Cu(II)], X = O(2)(-), OH(-), and RCO(2)(-), all with a common high-spin heme, thereby allowing an examination of electronic structure as dependent on the bridging atom or group and bridge structure. (Me(5)dien = 1,1,4,7,7-pentamethyldiethylenetriamine; Me(6)tren = tris(2-(dimethylamino)ethyl)amine; OEP = octaethylporphyrinate(2-).)     

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.     

Coordination Chemistry of 2,2'-Dipyridyl Diselenide: X-ray Crystal Structures of PySeSePy, [Zn(PySeSePy)Cl(2)], [(PySeSePy)Hg(C(6)F(5))(2)], [Mo(SePy)(2)(CO)(3)], [W(SePy)(2)(CO)(3)], and [Fe(SePy)(2)(CO)(2)] (PySeSePy = C(5)H(4)NSeSeC(5)H(4)N; SePy = [C(5)H(4)N(2-Se)-N,Se])

The coordination chemistry of 2,2'-dipyridyl diselenide (PySeSePy) (2) (C(10)H(8)N(2)Se(2)) has been investigated and its crystal structure has been determined (monoclinic, P2(1)/c, a = 10.129(2) ?, b = 5.7332(12) ?, c = 19.173(3) ?, beta = 101.493(8) degrees, Z = 4). In metal complexes the ligand was found to coordinate in three different modes, as also confirmed by X-ray structure determination. N,N'-coordination was found in the zinc complex [Zn(PySeSePy)Cl(2)] (3) (C(10)H(8)Cl(2)N(2)Se(2)Zn, triclinic, P&onemacr;, a = 7.9430(10) ?, b = 8.147(2) ?, c = 11.999(2) ?, alpha = 93.685(10) degrees, beta = 107.763(10) degrees, gamma = 115.440(10) degrees, Z = 2) and Se,Se'-coordination in the adduct of the ligand with bis(pentafluorophenyl)mercury(II) [PySeSePyHg(C(6)F(5))(2)] (5) (C(10)H(8)F(10)HgN(2)Se(2), monoclinic, P2(1)/n, a = 7.7325(10) ?, b = 5.9974(14) ?, c = 25.573, beta = 98.037(10) degrees, Z = 2), which however displays only weak interactions between selenium and mercury. The reaction of the ligand with norbornadiene carbonyl complexes of molybdenum and tungsten leads to reductive cleavage of the selenium-selenium bond with oxidation of the metal center and concomitant addition of the resulting selenolate to the metal carbonyl fragment. Thus the 7-coordinate complexes [Mo(SePy)(2)(CO)(3)] (6) (C(13)H(8)MoN(2)O(3)Se(2), monoclinic, P2(1)/n, a = 9.319(3) ?, b = 12.886(5) ?, c = 13.231(6) ?, beta = 109.23(3) degrees, Z = 4) and [W(SePy)(2)(CO)(3)] (7) (C(13)H(8)N(2)O(3)Se(2)W, monoclinic, P2(1)/n, a = 9.303(2) ?, b = 12.853(2) ?, c = 13.232(2) ?, beta = 109.270(10) degrees, Z = 4) were obtained. The same N,Se-coordination pattern emerges from the reaction of [Fe(2)(CO)(9)] with (2) leading to [Fe(SePy)(2)(CO)(2)] (8) (C(12)H(8)FeN(2)O(2)Se(2), monoclinic, P&onemacr;, a = 8.6691(14) ?, b = 12.443(2) ?, c = 14.085(2) ?, alpha = 105.811(10) degrees, beta = 107.533(8) degrees, gamma = 92.075(10) degrees, Z = 4).     

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.     

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.     

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.     

Ferromagnetic Mn(II).Cu(II) Exchange in the New Bimetallic Quasi-2-D Compound Cu(op)(2)MnCl(4) (op = 1,4-Diazacycloheptane)

The synthesis, crystal structure, and magnetic properties are reported for the new bimetallic compound Cu(op)(2)MnCl(4), where op = HN(CH(2))(5)NH. The compound, C(10)H(24)N(4)Cl(4)CuMn, crystallizes in the monoclinic space group P2(1)/n. Cell dimensions are as follows: a = 15.316(3) ?, b = 16.608(3) ?, c = 7.141(2) ?, beta = 100.01(5) degrees, Z = 4. The structure consists of well-separated and magnetically equivalent layers which are composed of chloride-bridged Cu(op)(2)MnCl(4) binuclear units connected by rather loose Cu-N-H.Cl-Mn contacts. The MnCl(4) fragment approximates tetrahedral symmetry. The Cu(II) geometry is (4 + 1) square-pyramidal with the apical position occupied by a bridging chloride ligand and the basal ones by the nitrogen atoms from the organic ligands. The shortest interlayer M.M separations, approximately 7 ?, are of the Mn.Cu type. Magnetic susceptibility and single-crystal EPR measurements for the compound have been carried out over the range 4-300 K. At room temperature the chiT product (per MnCu unit) has a value of 4.84 emu.mol(-)(1).K, close to that expected for uncoupled S = (5)/(2) and S = (1)/(2) spins. When the temperature is lowered, chiT remains almost constant until 80-90 K, slightly increases to reach a maximum at approximately 13 K (5.21 emu.mol(-)(1).K), and then rapidly decreases. Comparison between theory and experiment, made with use of both a mean field corrected dimer model and an approximate 2-D model, indicates that Mn(II).Cu(II) exchange is ferromagnetic within the dimers (J(1) approximately 2.6 cm(-)(1)) and antiferromagnetic among dimers, with J values between -0.07 and -0.03 cm(-)(1) (the interaction Hamiltonian is of the form H = -2JS(A).S(B)). Single-crystal EPR spectra recorded along the a, b, and c axes show a large temperature dependence of the g factors: at 4.2 K, g(a) = 2.10, g(b) = 1.96, and g(c) = 2.01. This pattern substantiates the presence of a 2-D magnetic structure with ferromagnetic intradimer exchange and interdimer antiferromagnetic exchange of weaker magnitude. The opposite signs of the interactions are ascribed to the local symmetries of the Cu(II) and Mn(II) ions.     

Tetranuclear and Pentanuclear Vanadium(IV/V) Carboxylate Complexes: [V(4)O(8)(NO(3))(O(2)CR)(4)](2-) and [V(5)O(9)X(O(2)CR)(4)](2-) (X = Cl(-), Br(-)) Salts

The syntheses and properties of tetra- and pentanuclear vanadium(IV,V) carboxylate complexes are reported. Reaction of (NBzEt(3))(2)[VOCl(4)] (1a) with NaO(2)CPh and atmospheric H(2)O/O(2) in MeCN leads to formation of (NBzEt(3))(2)[V(5)O(9)Cl(O(2)CPh)(4)] 4a; a similar reaction employing (NEt(4))(2)[VOCl(4)] (1b) gives (NEt(4))(2)[V(5)O(9)Cl(O(2)CPh)(4)] (4b). Complex 4a.MeCN crystallizes in space group P2(1)2(1)2(1) with the following unit cell dimensions at -148 degrees C: a = 13.863(13) ?, b = 34.009(43) ?, c = 12.773(11) ?, and Z = 4. The reaction between (NEt(4))(2)[VOBr(4)] (2a) and NaO(2)CPh under similar conditions gives (NEt(4))(2)[V(5)O(9)Br(O(2)CPh)(4)] (6a), and the use of (PPh(4))(2)[VOBr(4)] (2b) likewise gives (PPh(4))(2)[V(5)O(9)Br(O(2)CPh)(4)] (6b). Complex 6b crystallizes in space group P2(1)2(1)2(1) with the following unit cell dimensions at -139 degrees C: a = 18.638(3) ?, b = 23.557(4) ?, c = 12.731(2) ?, and Z = 4. The anions of 4a and 6b consist of a V(5) square pyramid with each vertical face bridged by a &mgr;(3)-O(2)(-) ion, the basal face bridged by a &mgr;(4)-X(-) (X = Cl, Br) ion, and a terminal, multiply-bonded O(2)(-) ion on each metal. The RCO(2)(-) groups bridge each basal edge to give C(4)(v)() virtual symmetry. The apical and basal metals are V(V) and V(IV), respectively (i.e., the anions are trapped-valence). The reaction of 1b with AgNO(3) and Na(tca) (tca = thiophene-2-carboxylate) in MeCN under anaerobic conditions gives (NEt(4))(2)[V(4)O(8)(NO(3))(tca)(4)] (7). Complex 7.H(2)O crystallizes in space group C2/c with the following unit cell dimensions at -170 degrees C: a = 23.606(4) ?, b = 15.211(3) ?, c = 23.999(5) ?, and Z = 4. The anion of 7 is similar to those of 4a and 6b except that the apical [VO] unit is absent, leaving a V(4) square unit, and the &mgr;(4)-X(-) ion is replaced with a &mgr;(4),eta(1)-NO(3)(-) ion. The four metal centers are now at the V(IV), 3V(V) oxidation level, but the structure indicates four equivalent V centers, suggesting an electronically delocalized system. Variable-temperature magnetic susceptibility data were collected on powdered samples of 4b, 6a, and 7 in the 2.00-300 K range in a 10 kG applied field. 4b and 6a both show a slow increase in effective magnetic moment (&mgr;(eff)) from approximately 3.6-3.7 &mgr;(B) at 320 K to approximately 4.5-4.6 &mgr;(B) at 11.0 K and then a slight decrease to approximately 4.2 &mgr;(B) at 2.00 K. The data were fit to the theoretical expression for a V(IV)(4) square with two exchange parameters J = J(cis)() and J' = J(trans)() (H = -2JS(i)()S(j)()): fitting of the data gave, in the format 4b/6a, J= +39.7/+46.4 cm(-)(1), J' = -11.1/-18.2 cm(-)(1) and g = 1.83/1.90, with the complexes possessing S(T) = 2 ground states. The latter were confirmed by magnetization vs field studies in the 2.00-30.0 K and 0.500-50.0 kG ranges: fitting of the data gave S(T) = 2 and D = 0.00 cm(-)(1) for both complexes, where D is the axial zero-field splitting parameter. Complex 7 shows a nearly temperature-independent &mgr;(eff) (1.6-2.0 &mgr;(B)) consistent with a single d electron per V(4) unit. The (1)H NMR spectra of 4b and 6a in CD(3)CN are consistent with retention of their pentanuclear structure on dissolution. The EPR spectrum of 7 in a toluene/MeCN (1:2) solution at approximately 25 degrees C yields an isotropic signal with a 29-line hyperfine pattern assignable to hyperfine interactions with four equivalent I = (7)/(2) (51)V nuclei.     

X-ray Crystallographic Study of the Ruthenium Blue Complexes [Ru(2)Cl(3)(tacn)(2)](PF(6))(2).4H(2)O, [Ru(2)Br(3)(tacn)(2)](PF(6))(2).2H(2)O, and [Ru(2)I(3)(tacn)(2)](PF(6))(2): Steric Interactions and the Ru-Ru "Bond Length"

X-ray crystal structures are reported for the following complexes: [Ru(2)Cl(3)(tacn)(2)](PF(6))(2).4H(2)O (tacn = 1,4,7-triazacyclononane), monoclinic P2(1)/n, Z = 4, a = 14.418(8) ?, b = 11.577(3) ?, c = 18.471(1) ?, beta = 91.08(5) degrees, V = 3082 ?(3), R(R(w)) = 0.039 (0.043) using 4067 unique data with I > 2.5sigma(I) at 293 K; [Ru(2)Br(3)(tacn)(2)](PF(6))(2).2H(2)O, monoclinic P2(1)/a, Z = 4, a = 13.638(4) ?, b = 12.283(4) ?, c = 18.679(6) ?, beta = 109.19(2) degrees, V = 3069.5 ?(3), R(R(w)) = 0.052 (0.054) using 3668 unique data with I > 2.5sigma(I) at 293 K; [Ru(2)I(3)(tacn)(2)](PF(6))(2), cubic P2(1)/3, Z = 3, a = 14.03(4) ?, beta = 90.0 degrees, V = 2763.1(1) ?(3), R (R(w)) = 0.022 (0.025) using 896 unique data with I > 2.5sigma(I) at 293 K. All of the cations have cofacial bioctahedral geometries, although [Ru(2)Cl(3)(tacn)(2)](PF(6))(2).4H(2)O, [Ru(2)Br(3)(tacn)(2)](PF(6))(2).2H(2)O, and [Ru(2)I(3)(tacn)(2)](PF(6))(2) are not isomorphous. Average bond lengths and angles for the cofacial bioctahedral cores, [N(3)Ru(&mgr;-X)(3)RuN(3)](2+), are compared to those for the analogous ammine complexes [Ru(2)Cl(3)(NH(3))(6)](BPh(4))(2) and [Ru(2)Br(3)(NH(3))(6)](ZnBr(4)). The Ru-Ru distances in the tacn complexes are longer than those in the equivalent ammine complexes, probably as a result of steric interactions.     

Spectroelectrochemical Studies of Copper(I) Complexes with Binaphthyridine and Biquinoline Ligands. Crystal Structure Determination of Bis(6,7-dihydrodipyrido[2,3-b:3',2'-j][1,10]phenanthroline)copper(I) Tetrafluoroborate

The electrochemical and spectral properties of some copper(I) polypyridyl complexes based on 6,7-dihydrodibenzo[b,j][1,10]phenanthroline, dmbiq, and 6,7-dihydrodipyrido[2,3-b:3',2'-j][1,10]phenanthroline, dmbinap, are reported. These complexes are [Cu(dmbiq)(2)](+), 1; [Cu(dmbiq)(PPh(3))(2)](+), 2; [Cu(dmbinap)(2)](+), 3; and [Cu(dmbinap)(PPh(3))(2)](+), 4. 3 and 4 may be reduced to form ligand-based radical anion species. The resonance Raman spectra of 3(*)()(-)() and 4(*)()(-)() are almost identical and correspond closely to the spectrum of dmbinap(*)()(-)() and the reported spectra of complexes containing 2,2'-biquinoline radical anion moieties. Reduction processes for 1 and 2 are irreversible. For 1 the electronic spectral changes arising from reduction suggest demetallation of the complex. The structure of [Cu(C(18)H(12)N(4))(2)][BF(4)].CH(2)Cl(2) (3[BF(4)].CH(2)Cl(2)) was determined by single-crystal X-ray diffraction. It crystallized in the monoclinic space group P2(1)/c with cell dimensions a = 14.059(7) ?, b = 15.058(6) ?, c = 16.834(9) ?, beta = 111.56(5) degrees, Z = 4, rho(calcd) = 1.611 g/cm(3), and R(F(o)) = 0.0497.     

Osmium Complexes of 1,4,7-Triazacyclononane (tacn) and 1,4,7-Trimethyl-1,4,7-triazacyclononane (Me(3)tacn) and the X-ray Crystal Structure of [(Me(3)tacn)Os(eta(6)-C(6)H(5)BPh(3))]BPh(4).CH(3)CN

The complexes of osmium with tacn (1,4,7-triazacyclononane) and Me(3)tacn (1,4,7-trimethyl-1,4,7-triazacyclononane), [LOs (eta(6)-C(6)H(6))](PF(6))(2) (L = tacn) and LOsCl(3) (L = tacn, Me(3)tacn), have been prepared by substitution of L on [Os(eta(6)-C(6)H(6))Cl(2)](2) or [Os(2)Cl(8)](2)(-), respectively. Reaction of LOsCl(3) with neat triflic acid leads to partial replacement of chloride and formation of the binuclear Os(III)-Os(III) complexes [LOs(&mgr;-Cl(3))OsL](PF(6))(3) (L = tacn, Me(3)tacn). The binuclear nature was established by NMR spectroscopy and elemental analysis and, for L = tacn, a partially refined X-ray crystal structure which shows the Os-Os separation to be 2.667 ?, indicative of significant metal-metal bonding. Reduction of [LOs(&mgr;-Cl(3))OsL](3+) over zinc amalgam in either aqueous or non-aqueous solution yields the intensely colored Os(II)-Os(III) mixed-valence ions [LOs(&mgr;-Cl(3))OsL](2+). Electrochemical measurements on [LOs(&mgr;-Cl(3))OsL](3+) in CH(3)CN reveal the reversible formation of the mixed valence ions. These are further reduced at lower potential to the Os(II)-Os(II) binuclear species, reversibly for L = Me(3)tacn. (Me(3)tacn)OsCl(3) is oxidized by persulfate ion to give [(Me(3)tacn)OsCl(3)](+); zinc amalgam reduction in an aqueous solution at high concentration produces the binuclear complex [(Me(3)tacn)Os(&mgr;-Cl(3))Os(Me(3)tacn)](3+) or, at low concentration, a solution containing an air sensitive osmium(II) species. Addition of BPh(4)(-) results in the eta(6)-arene zwitterion [(Me(3)tacn)Os(eta(6)-C(6)H(5)BPh(3))](+), which was characterized by X-ray diffraction on the BPh(4)(-) salt. The compound crystallizes in the triclinic space group P1 with a = 11.829(2) ?, b = 12.480(3) ?, c = 17.155(4) ?, alpha = 84.42(2) degrees, beta = 83.52(2) degrees, gamma = 71.45(2) degrees, V = 2380(2) ?(3), Z = 2, and R = 7.62%, and R(w) = 7.39%.