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.     

Reactions of the Dirhenium(II) Complexes Re(2)X(4)(dppm)(2) (X = Cl, Br; dppm = Ph(2)PCH(2)PPh(2)) with Isocyanides. 10.(1) Synthesis and Characterization of the Complex [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3) and Several Isomeric Forms of [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)]Y (Y = PF(6), O(3)SCF(3))

The reactions of the unsymmetrical, coordinatively unsaturated dirhenium(II) complexes [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)]Y (XylNC = 2,6-dimethylphenyl isocyanide; Y = O(3)SCF(3) (3a), PF(6) (3b)) with XylNC afford at least three isomeric forms of the complex cation [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](+). Two forms have very similar bis(&mgr;-halo)-bridged edge-sharing bioctahedral structures of the type [(CO)BrRe(&mgr;-Br)(2)(&mgr;-dppm)(2)Re(CNXyl)(2)]Y (Y = O(3)SCF(3) (4a/4a'), PF(6) (4b/4b')), while the third is an open bioctahedron [(XylNC)(2)BrRe(&mgr;-dppm)(2)ReBr(2)(CO)]Y (Y = O(3)SCF(3) (5a), PF(6) (5b)). While the analogous chloro complex cation [Re(2)Cl(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](+) was previously shown to exist in three isomeric forms, only one of these has been found to be structurally similar to the bromo complexes (i.e. the isomer analogous to 5a and 5b). The reaction of 3a with CO gives the salt [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3) (7), in which the edge-sharing bioctahedral cation [(XylNC)BrRe(&mgr;-Br)(&mgr;-CO)(&mgr;-dppm)(2)ReBr(CO)](+) has an all-cis arrangement of pi-acceptor ligands. The Re-Re distances in the structures of 4b', 5a, and 7 are 3.0456(8), 2.3792(7), and 2.5853(13) ?, respectively, and accord with formal Re-Re bond orders of 1, 3, and 2, respectively. Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](PF(6))(0.78)(ReO(4))(0.22).CH(2)Cl(2) (4b') at 295 K: monoclinic space group P2(1)/n (No. 14) with a = 19.845(4) ?, b = 16.945(5) ?, c = 21.759(3) ?, beta = 105.856(13) degrees, V = 7038(5) ?(3), and Z = 4. The structure was refined to R = 0.060 (R(w) = 0.145) for 14 245 data (F(o)(2) > 2sigma(F(o)(2))). Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)]O(3)SCF(3).C(6)H(6) (5a) at 173 K: monoclinic space group P2(1)/n (No. 14) with a = 14.785(3) ?, b = 15.289(4) ?, c = 32.067(5) ?, beta = 100.87(2) degrees, V=7118(5) ?(3), and Z = 4. The structure was refined to R = 0.046 (R(w) = 0.055) for 6962 data (I > 3.0sigma(I)). Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3).Me(2)CHC(O)Me (7) at 295 K: monoclinic space group P2(1)/n (No. 14) with a = 14.951(2) ?, b = 12.4180(19) ?, c = 40.600(5) ?, beta = 89.993(11) degrees, V = 7537(3) ?(3), and Z = 4. The structure was refined to R = 0.074 (R(w) = 0.088) for 6595 data (I > 3.0sigma(I)).     

Bis(pyrazolylethyl) Ether Ligation to Zinc and Cobalt: Meridional vs Facial Coordination and the Suitability of Such Ligands in Providing a NNO Donor Set for Modeling Bioinorganic Aspects of Zinc Chemistry

The structures of bis(pyrazolylethyl) ether derivatives of zinc and cobalt, namely [eta(3)-O(CH(2)CH(2)pz(Pr)()i()2)(2)]Zn(NO(3))(2) and [eta(3)-O(CH(2)CH(2)pz(Me)()2)(2)]Co(NO(3))(2), have been determined with a view to addressing the applicability of such ligands in modeling bioinorganic aspects of zinc chemistry. Specific consideration is given to the possibility that bis(pyrazolylethyl) ether ligands may provide an NNO donor system which may model aspects of the binding of zinc to protein backbones in enzymes such as thermolysin. The structural studies demonstrate that the bis(pyrazolylethyl) ether ligands do indeed coordinate via each of their NNO functionalities but that the relationship to the enzyme is limited by the adoption of meridional rather than facial coordination geometries. [eta(3)-O(CH(2)CH(2)pz(Pr)()i()2)(2)]Zn(NO(3))(2) is monoclinic, P2(1)/c (No. 14), with a = 11.619(2) ?, b = 14.380(3) ?, c = 16.757(2) ?, beta = 90.44(2) degrees, and Z = 4. [eta(3)-O(CH(2)CH(2)pz(Me)()2)(2)]Co(NO(3))(2) is monoclinic, C2/c (No. 15), with a = 17.136(3) ?, b = 10.505(2) ?, c = 11.121(2) ?, beta = 104.62(3) degrees, and Z = 4.     

Structural Chemistry of Poly(ethylene glycol) Complexes of Lead(II) Nitrate and Lead(II) Bromide

The reaction of 1:1 stoichiometries (1:1.5 for the nitrate/tetraethylene glycol (EO4) and pentaethylene glycol (EO5) complexes) of PbX(2) (X = NO(3), Br) with five- to eight-donor poly(ethylene glycols) (PEGs) in 3:1 CH(3)CN/CH(3)OH (CH(3)CN only for the nitrate/EO5 complex) followed by solvent evaporation resulted in six crystalline materials upon which X-ray structural analyses were carried out: [Pb(NO(3))(2)(EO4)](n)(), [Pb(NO(3))(2)(EO5)], [Pb(NO(3))(2)(EO6)], [PbBr(EO5)(&mgr;-Br)PbBr(2)].H(2)O, [PbBr(NCMe)(EO6)](2)[PbBr(2)(EO6)][PbBr(3)](2), and [PbBr(EO7)][PbBr(3)]. The nitrates crystallize as tight ion pairs with the PEG ligands coordinating in an equatorial plane around the Pb(2+) ions. Because EO4 has only five oxygen donors, this complex exhibits steric unsaturation which is overcome by a monodentate interaction with a third nitrate anion that is also coordinated to a neighboring Pb(2+) ion. The six donors of EO5 coordinate in an equatorial plane resulting in a 10-coordinate complex with trans, twisted, bidentate nitrate anions. The seven-donor hexaethylene glycol (EO6) only uses six of its oxygen donors to coordinate Pb(2+). [Pb(NO(3))(2)(EO4)](n)() is monoclinic, P2(1)/c, with a = 7.902(3) ?, b = 22.136(6) ?, c = 8.910(2) ?, beta = 90.96(3) degrees, and Z = 4. [Pb(NO(3))(2)(EO5)] is triclinic P&onemacr;, with a = 9.332(3) ?, b = 10.025(3) ?, c = 11.688(4) ?, alpha = 68.41(3) degrees, beta = 68.39(3) degrees, gamma = 68.58(3) degrees, and Z = 2. [Pb(NO(3))(2)(EO6)] is monoclinic P2(1)/c, with a = 16.289(4) ?, b = 10.773(4) ?, c = 12.329(4) ?, beta = 106.77(2) degrees, and Z = 4. Lead(II) bromide complexes with PEGs tend to crystallize as PEG complexed cations with polymeric lead(II) bromide anions. In the EO5 complex, bromide anions in the polymer also coordinate to the PEG-wrapped Pb(2+) cations. The hexa- and heptaethylene glycol (EO6 and EO7, respectively) complexes contain discreet ions. In these halide complexes, EO7 is the only PEG to expand the Pb(2+) coordination number from eight to nine. [PbBr(EO5)(&mgr;-Br)PbBr(2)].H(2)O is triclinic P&onemacr;, with a = 7.922(6) ?,b = 15.802(9) ?, c = 19.001(9) ?, alpha = 73.19(8) degrees, beta = 88.91(9) degrees, gamma = 87.22(9) degrees, and Z = 4. [PbBr(NCMe)(EO6)](2)[PbBr(2)(EO6)][PbBr(3)](2) is monoclinic P2(1)/c, with a = 14.389(4) ?, b = 31.931(9) ?, c = 8.029(2) ?, beta = 97.76(3) degrees, and Z = 2. [PbBr(EO7)][PbBr(3)] is monoclinic Cc, with a = 13.165(3) ?, b = 24.732(5) ?, c = 8.007(1) ?, beta = 94.58(2) degrees, and Z = 4.     

Preparation, Molecular and Electronic Structures, and Magnetic Properties of Face-Sharing Bioctahedral Titanium(III) Compounds: [PPh(4)][Ti(2)(&mgr;-Cl)(3)Cl(4)(PR(3))(2)

Reduction of TiCl(4) with 1 equiv of HSnBu(3) followed by addition of [PPh(4)]Cl and then PR(3) leads to two new dinuclear titanium(III) compounds, [PPh(4)][Ti(2)(&mgr;-Cl)(3)Cl(4)(PR(3))(2)] (R = Et and R(3) = Me(2)Ph), both of which contain an anion with the face-sharing bioctahedral type structure. Their crystal structures are reported. [PPh(4)][Ti(2)(&mgr;-Cl)(3)Cl(4)(PEt(3))(2)].2CH(2)Cl(2) crystallized in the triclinic space group P&onemacr;. Cell dimensions: a = 12.461(1) ?, b = 20.301(8) ?, c = 11.507(5) ?, alpha = 91.44 degrees, beta = 113.27(1) degrees, gamma = 104.27(2) degrees, and Z = 2. The distance between titanium atoms is 3.031(2) ?. [PPh(4)][Ti(2)(&mgr;-Cl)(3)Cl(4)(PMe(2)Ph)(2)].CH(2)Cl(2) also crystallized in the triclinic space group P&onemacr; with cell dimensitions a = 11.635(4) ?, b = 19.544(3) ?, c = 11.480(3) ?, alpha = 100.69(2) degrees, beta = 109.70(1) degrees, gamma = 95.08(2) degrees, and Z = 2. The distance between titanium atoms in this compound is 2.942(1) ?. Variable temperature magnetic susceptibilities were measured for [PPh(4)][Ti(2)(&mgr;-Cl)(3)Cl(4)(PEt(3))(2)]. Electronic structure calculations were carried out for a model ion, [Ti(2)(&mgr;-Cl)(3)Cl(4)(PH(3))(2)](-), and another well-known anion, [Ti(2)(&mgr;-Cl)(3)Cl(6)](3)(-), by employing an ab initio configuration interaction method. The results of the calculations reveal that the metal-metal interaction in these Ti(III) face-sharing compounds can be best described by strong antiferromagnetic coulping that leads to a singlet ground state and a thermally accessible triplet first excited state. Accordingly the measured magnetic data were satisfactorily fitted to a spin-only formula.     

Chemistry of Thiobenzoates: Syntheses, Structures, and NMR Spectra of Salts of [M(SOCPh)(3)](-) (M = Zn, Cd, Hg)

The salts (Ph(4)E)[M(SOCPh)(3)] (M = Zn, Cd, or Hg; E = P or As) are produced by the reaction of Zn(NO(3))(2).6 H(2)O, Cd(NO(3))(2).4H(2)O or HgCl(2) with Et(3)NH(+)PhCOS(-) and (Ph(4)E)X (E = P, X = Br; E = As, X = Cl) in aqueous MeOH in the ratios M(II):PhCOS(-):Ph(4)E(+) = 1:>/=3:>/=1. The crystal structures of (Ph(4)P)[Zn(SOCPh)(3)] (1), (Ph(4)As)[Cd(SOCPh)(3)] (2) and (Ph(4)P)[Hg(SOCPh)(3)] (3) have been determined by single-crystal X-ray diffraction experiments. Crystal data for 1: triclinic; space group P&onemacr;; Z = 2; a = 10.819(2) ?, b = 13.219(3) ?, c = 15.951(3) ?; alpha = 101.75(2) degrees, beta = 97.92(1) degrees, gamma = 109.18(2) degrees. Crystal data for 2: triclinic; space group P&onemacr;; Z= 2; a = 10.741(2) ?, b = 13.168(2) ?, c = 15.809(2) ?; alpha = 101.00(1) degrees, beta = 97.65(1) degrees, gamma = 109.88(1) degrees. Crystal data for 3: monoclinic; space group P2(1)/n; Z = 4; a = 13.302(2) ?, b = 14.276(2) ?, c = 21.108(2) ?; beta = 90.92(1) degrees. The compounds 1 and 2 are isomorphous and isostructural. In the anions [M(SOCPh)(3)](-) the metal atoms have trigonal planar coordination by three sulfur atoms. The metal atoms are further more weakly coordinated intramolecularly to one (M = Hg) or two (M = Zn, Cd) thiobenzoate oxygen atom(s). Using the Bond Valence approach it is found that the contribution of M.O bonding to the total bonding is in the order Cd > Zn > Hg. The metal ((113)Cd, (199)Hg) NMR signals of [M(SOCPh)(3)](-) (M = Cd, Hg) are more shielded than those found for MS(3) kernels in thiolate complexes, a difference attributed to the M(.)O bonding in the thiobenzoate complexes. The (113)Cd resonance of [Cd(SOCPh)(3)](-) in dilute solution is in the region anticipated from dilution data for [Na(Cd{SOCPh}(3))(2)](-).     

Synthesis and Characterization of Heterodinuclear IrCo, RuCo, IrNi, and RuNi Complexes Containing Pyrazolate and Pyrazolylborate Ligands

Treatment of the metallo ligands [ML(pz)(2)(Hpz)] (pz = pyrazolate; L = C(5)Me(5), M = Ir (1); L = mesitylene, M = Ru (3)) with [M'Cl{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (4), Ni (5)) yields heterodinuclear complexes of formula [LM(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (L = C(5)Me(5); M = Ir; M' = Co (6), Ni (7). L = mesitylene; M = Ru; M' = Co (8)). The related complex [Ru(eta(6)-p-cymene)(pz)(2)(Hpz)] (2) reacts with equimolar amounts of 4 or 5 to give mixtures of the corresponding bis(&mgr;-pyrazolato) &mgr;-chloro complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (9), Ni (10)) and the triply pyrazolato-bridged complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(3)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (11), Ni (12)). Complex 1 reacts with 5 in the presence of KOH to give the IrNi complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(3)Ni{HB(3-i-Pr-4-Br-pz)(3)}] (13) whereas its reaction with 4 and KOH rendered the bis(&mgr;-pyrazolato) &mgr;-hydroxo complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(2)(&mgr;-OH)Co{HB(3-i-Pr-4-Br-pz)(3)}] (14). The molecular structure of the heterobridged IrCo complex (6) and those of the homobridged RuNi (12) and IrNi (13) complexes have been determined by X-ray analyses. Compound 6 crystallizes in the monoclinic space group P2(1)/n, with a = 10.146(5) ?, b = 18.435(4) ?, c = 22.187(13) ?, beta = 97.28(4) degrees, and Z = 4. Complex 12 is monoclinic, space group P2(1), with a = 10.1169(7) ?, b = 21.692(2) ?, c = 11.419(1) ?, beta = 112.179(7) degrees, and Z = 2. Compound 13 crystallizes in the monoclinic space group Cc, with a = 13.695(2) ?, b = 27.929(6) ?, c = 13.329(2) ?, beta = 94.11(4) degrees, and Z = 4. All the neutral complexes 6, 12, and 13 consist of linear M.M'.B backbones with two (6) or three (12, 13) pyrazolate ligands bridging the dimetallic M.M' units and three substituted 3-i-Pr-4-Br-pz groups joining M' to the boron atoms. The presence in the proximity of the first-row metal M' of the three space-demanding isopropyl substituents of the pyrazolate groups induces a significant trigonal distortion of the octahedral symmetry, yielding clearly different M'-N bond distances on both sides of the ideal octahedral coordination sphere of these metals.     

A Six-Coordinate Tris(3,5-dimethyl-1-pyrazolyl)methane-Thallium(I) Complex with a Stereochemically Inactive Lone Pair: Syntheses and Solid State Structures of {[HC(3,5-Me(2)pz)(3)](2)Tl}PF(6) and {[HC(3,5-Me(2)pz)(3)]Tl}PF(6) (pz = Pyrazolyl)

The addition of the tris(pyrazolyl)methane ligand HC(3,5-Me(2)pz)(3) (pz = pyrazolyl ring) to a THF solution of TlPF(6) results in the immediate precipitation of {[HC(3,5-Me(2)pz)(3)](2)Tl}PF(6). The structure has been determined crystallographically. The arrangement of the nitrogen donor atoms about the thallium is best described as a trigonally distorted octahedron. The thallium atom sits on a crystallographic center of inversion; thus the planes formed by the three nitrogen donor atoms of each ligand are parallel. The Tl-N bond distances range from 2.891(5) to 2.929(5) ? (average = 2.92) ?. The lone pair on thallium is clearly stereochemically inactive and does not appear to influence the structure. The pyrazolyl rings are planar, but are tilted with respect to the thallium atom so as to open up the N.N intraligand bite distances. The thallium(I) complex with a ligand to metal ratio of 1/1, {[HC(3,5-Me(2)pz)(3)]Tl}PF(6), is prepared in acetone by the reaction of equimolar amounts of HC(3,5-Me(2)pz)(3) and TlPF(6). The structure of the cation is a trigonal pyramid, with Tl-N bond distances that range from 2.64(1) to 2.70(1) ? (average = 2.67) ?. Pyrazolyl ring tilting is also observed in this complex, but the degree of tilting is smaller. Crystal data for {[HC(3,5-Me(2)pz)(3)](2)Tl}PF(6): monoclinic, P2(1)/c, a = 9.210(6) ?, b = 13.36(1) ?, c = 16.067(8) ?, beta = 92.48(5) degrees, V = 1975(2) ?(3), Z = 2, R = 0.029. For {[HC(3,5-Me(2)pz)(3)]Tl}PF(6): monoclinic, P2(1)/n, a = 10.685(2) ?, b = 16.200(5) ?, c = 13.028(3) ?, beta = 94.02(2) degrees, V = 2249.6(8) ?(3), Z = 4, R = 0.042.     

Syntheses of Cationic, Six-Coordinate Cadmium(II) Complexes Containing Tris(pyrazolyl)methane Ligands. Influence of Charge on Cadmium-113 NMR Chemical Shifts

Treating a thf (thf = tetrahydrofuran) suspension of Cd(acac)(2) (acac = acetylacetonate) with 2 equiv of HBF(4).Et(2)O results in the immediate formation of [Cd(2)(thf)(5)](BF(4))(4) (1). Crystallization of this complex from thf/CH(2)Cl(2) yields [Cd(thf)(4)](BF(4))(2) (2), a complex characterized in the solid state by X-ray crystallography. Crystal data: monoclinic, P2(1)/n, a = 7.784(2) ?, b = 10.408(2) ?, c = 14.632(7) ?, beta = 94.64(3) degrees, V = 1181.5(6) ?(3), Z = 2, R = 0.0484. The geometry about the cadmium is octahedral with a square planar arrangement of the thf ligands and a fluorine from each (BF(4))(-) occupying the remaining two octahedral sites. Reactions of [Cd(2)(thf)(5)](BF(4))(4) with either HC(3,5-Me(2)pz)(3) or HC(3-Phpz)(3) yield the dicationic, homoleptic compounds {[HC(3,5-Me(2)pz)(3)](2)Cd}(BF(4))(2) (3) and {[HC(3-Phpz)(3)](2)Cd}(BF(4))(2) (4) (pz = 1-pyrazolyl). The solid state structure of 3 has been determined by X-ray crystallography. Crystal data: rhombohedral, R&thremacr;, a = 12.236(8) ?, c = 22.69(3) ?, V = 2924(4) ?(3), Z = 3, R = 0.0548. The cadmium is bonded to the six nitrogen donor atoms in a trigonally distorted octahedral arrangement. Four monocationic, mixed ligand tris(pyrazolyl)methane-tris(pyrazolyl)borate complexes {[HC(3,5-Me(2)pz)(3)][HB(3,5-Me(2)pz)(3)]Cd}(BF(4)) (5), {[HC(3,5-Me(2)pz)(3)][HB(3-Phpz)(3)]Cd}(BF(4)) (6), {[HC(3-Phpz)(3)][HB(3,5-Me(2)pz)(3)]Cd}(BF(4)) (7), and {[HC(3-Phpz)(3)][HB(3-Phpz)(3)]Cd}(BF(4)) (8) are prepared by appropriate conproportionation reactions of 3or 4 with equimolar amounts of the appropriate homoleptic neutral tris(pyrazolyl)borate complexes [HB(3,5-Me(2)pz)(3)](2)Cd or [HB(3-Phpz)(3)](2)Cd. Solution (113)Cd NMR studies on complexes 3-8 demonstrate that the chemical shifts of the new cationic, tris(pyrazolyl)methane complexes are very similar to the neutral tris(pyrazolyl)borate complexes that contain similar substitution of the pyrazolyl rings.     

Aluminum Amides Derived from Metalation of N,N'-Bis(trimethylsilyl)ethylenediamine

The reaction of N,N'-bis(trimethylsilyl)ethylenediamine with H(3)Al.NMe(3) gives products based on metalation (H(2) elimination), [{[CH(2)N(SiMe(3))](2)AlH}(2)] (1) and [{CH(2)N(SiMe(3))}(2)AlN(SiMe(3))CH(2)CH(2)N(H)SiMe(3)] (2), as well as products derived from N-Si bond cleavage and metalation, [{[CH(2)N(SiMe(3))](2)AlH}(2){HAlN(SiMe(3))CH(2)CH(2)NAlH(2)}] (4) and [H(2)Al{CH(2)N(SiMe(3))}(2)AlN(SiMe(3))CH(2)CH(2)NAl(H)(2).NMe(3)}] (5). Similarly, [Me(3)SiN(H)CH(2)CH(2)N(SiMe(3))AlCl(2)] (3) was isolated as the redistributed/metalated product from the reaction of the same diamine with H(2)Al(Cl).NMe(3). The following crystal data were obtained: (1) monoclinic, space group P2(1)/c (No. 14), a = 13.636(4) ?, b = 9.565(3) ?, c = 22.683(4) ?, beta = 105.67(2) degrees, Z = 4; (2) monoclinic, space group C2/c (No. 15), a = 31.887(3) ?, b = 10.145(6) ?, c = 17.718(3) ?, beta = 100.36(1) degrees, Z = 8; (3) triclinic, space group P&onemacr; (No. 2), a = 11.762(3) ?, b = 11.927(3) ?, c = 7.288(2) ?, alpha = 107.46(2) degrees, beta = 95.29(2) degrees, gamma = 110.41(2) degrees, Z = 2; (4) triclinic, space group P&onemacr; (No. 2), a = 13.884(4) ?, b = 15.379(4) ?, c = 11.044(2) ?, alpha = 102.11(2) degrees, beta = 103.85(2) degrees, gamma = 109.28(2) degrees, Z = 2; (5) triclinic, space group P&onemacr; (No. 2), a = 10.925(5) ?, b = 11.060(5) ?, c = 12.726(4) ?, alpha = 92.38(3) degrees, beta = 95.67(2) degrees, gamma = 96.90(2) degrees, Z = 2.     

Ruthenium Complexes Containing "Noninnocent" o-Benzoquinone Diimine/o-Phenylenediamide(2-) Ligands. Synthesis and Crystal Structure of the Nitrido-Bridged Complex [{LRu(o-C(6)H(4)(NH)(2))}(2)(&mgr;-N)](PF(6))(2).3CH(3)CN.C(6)H(5)CH(3)

Reaction of LRu(III)Cl(3) (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) with 1,2-phenylenediamine (opdaH(2)) in H(2)O in the presence of air affords [LRu(II)(bqdi)(OH(2))](PF(6)) (1), where (bqdi) represents the neutral ligand o-benzoquinone diimine. From an alkaline methanol/water mixture of 1 was obtained the dinuclear species [{LRu(II)(bqdi)}(2)(&mgr;-H(3)O(2))](PF(6))(3) (1a). The coordinated water molecule in 1 is labile and can be readily substituted under appropriate reaction conditions by acetonitrile, yielding [LRu(II)(bqdi)(CH(3)CN)](PF(6))(2) (2), and by iodide and azide anions, affording [LRu(II)(bqdi)I](PF(6)).0.5H(2)O (3) and [LRu(bqdi)(N(3))](PF(6)).H(2)O (4), respectively. Heating of solid 4 in vacuum at 160 degrees C generates N(2) and the dinuclear, nitrido-bridged complex [{LRu(o-C(6)H(4)(NH)(2))}(2)(&mgr;-N)](PF(6))(2) (5). Complex 5 is a mixed-valent, paramagnetic species containing one unpaired electron per dinuclear unit whereas complexes 1-4 are diamagnetic. The crystal structures of 1, 1a.3CH(3)CN, 3, 4.H(2)O, and 5.3CH(3)CN.0.5(toluene) have been determined by X-ray crystallography: 1 crystallizes in the monoclinic space group P2(1)/m, Z = 2, with a = 8.412(2) ?, b = 15.562(3) ?, c = 10.025 ?, and beta = 109.89(2) degrees; 1a.3CH(3)CN, in the monoclinic space group C2/c, Z = 4, with a = 19.858(3) ?, b = 15.483(2) ?, c = 18.192(3) ?, and beta = 95.95(2) degrees; 3, in the orthorhombic space group Pnma, Z = 4, with a = 18.399(4) ?, b = 9.287(2) ?, and c = 12.052(2) ?, 4.H(2)O, in the monoclinic space group P2(1)/c, Z = 4, with a = 8.586(1) ?, b = 15.617(3) ?, c = 16.388(5) ?, and beta = 90.84(2) degrees; and 5.3CH(3)CN.0.5(toluene), in the monoclinic space group P2(1)/c, Z = 4, with a = 15.003(3) ?, b = 16.253(3) ?, c = 21.196(4) ?, and beta = 96.78(3) degrees. The structural data indicate that in complexes 1-4 the neutral o-benzoquinone diimine ligand prevails. In contrast, in 5 this ligand has predominantly o-phenylenediamide character, which would render 5 formally a mixed-valent Ru(IV)Ru(V) species. On the other hand, the Ru-N bond lengths of the Ru-N-Ru moiety at 1.805(5) and 1.767(5) ? are significantly longer than those in other crystallographically characterized Ru(IV)=N=Ru(IV) units (1.72-1.74 ?). It appears that the C(6)H(4)(NH)(2) ligand in 5 is noninnocent and that formal oxidation state assignments to the ligands or metal centers are not possible.     

Characterization of Five-Coordinate Ruthenium(II) Phosphine Complexes by X-ray Diffraction and Solid-State (31)P CP/MAS NMR Studies and Their Reactivity with Sulfoxides and Thioethers

31P CP/MAS NMR spectroscopy is examined as a method of characterization for ruthenium(II) phosphine complexes in the solid state, and the results are compared with X-ray crystallographic data determined for RuCl(2)(dppb)(PPh(3)) (dppb = Ph(2)P(CH(2))(4)PPh(2)), RuBr(2)(PPh(3))(3), and the previously determined RuCl(2)(PPh(3))(3). Crystals of RuBr(2)(PPh(3))(3) (C(54)H(45)Br(2)P(3)Ru) are monoclinic, space group P2(1)/a, with a = 12.482(4) ?, b = 20.206(6) ?, c = 17.956(3) ?, beta = 90.40(2) degrees, and Z = 4, and those of RuCl(2)(dppb)(PPh(3)) (C(46)H(43)Cl(2)P(3)Ru) are also monoclinic, space group P2(1)/n, with a = 10.885(2) ?, b = 20.477(1) ?, c = 18.292(2) ?, beta = 99.979(9) degrees, and Z = 4. The structure of RuBr(2)(PPh(3))(3) was solved by direct methods, and that of RuCl(2)(dppb)(PPh(3)) was solved by the Patterson method. The structures were refined by full-matrix least-squares procedures to R = 0.048 and 0.031 (R(w) = 0.046 and 0.032) for 5069 and 5925 reflections with I >/= 3sigma(I), respectively. Synthetic routes to RuBr(2)(dppb)(PPh(3)) and [RuBr(dppb)](2)(&mgr;(2)-dppb) are reported. The reactivity of RuCl(2)(dppb)(PPh(3)) with the neutral two-electron donor ligands (L) dimethyl sulfoxide, tetramethylene sulfoxide, tetrahydrothiophene, and dimethyl sulfide to give [(L)(dppb)Ru(&mgr;-Cl)(3)RuCl(dppb)] is discussed.     

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).     

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.     

Iodination of alpha-Phosphino Enolate Complexes of Palladium(II) and Platinum(II). Synthesis and Crystal Structures of [(dmba)Pd{Ph(2)PC(I)C(O)Ph}] and of the Dipalladium(II) Complex [(dmba)Pd{Ph(2)PCC(O)Ph}Pd(I)(tmeda)] Obtained by Palladium(0) Insertion into the Carbon-Iodine Bond

Electrophilic attack of 1 equiv of I(2) on a PC(sp)2 carbon of the Pt(II) complex (1) afforded (2) in 90% yield. Complex 2 was subsequently deprotonated by NaOEt in ethanol to give the bis(enolato) complex (3). This alpha-phosphino, alpha-iodo enolato complex was obtained directly and quantitatively by the reaction of 1 with 1 equiv of N-iodosuccinimide (NIS). When 2 equiv of NIS was used, the symmetrical complex (4) was formed selectively. In contrast to I(2), NIS was also able to functionalize the phosphino enolate ligand of complexes to give the corresponding iodo derivatives (C N = dmba (5) or 8-mq (6)). These represent the first examples in which a phosphino enolate C-H bond has been directly functionalized, i.e. replaced by a C-X bond. Attempts to use this procedure with or with were unsuccessful. Reaction of 5 with Pd(dba)(2) in the presence of tetramethylenediamine (tmeda) or 2,2'-bipyridine (bipy) afforded (7) and (8), respectively. The solid state structures of complexes 5 and 7.CH(2)Cl(2) have been determined by single-crystal X-ray diffraction: 5 crystallizes in the monoclinic space group P2(1)/n with Z = 4 in a unit cell of dimensions a = 12.867(3) ?, b = 10.625(3) ?, c = 19.509(6) ?, and beta = 102.23(2) degrees; 7.CH(2)Cl(2) crystallizes in the monoclinic space group C2/c with Z = 8 in a unit cell of dimensions a = 35.906(3) ?, b = 13.565(3) ?, c = 15.775(2) ?, and beta = 95.099(10) degrees. Complex 7 contains two palladium(II) centers, in a square-planar environment, connected by the P-C unit of a phosphino enolate ligand which adopts an unprecedented &mgr;-eta(2)(P,C):eta(2)(P,O) bonding mode. The two coordination planes are almost orthogonal and make a dihedral angle of 88.0(2) degrees, which minimizes the steric hindrance between the ligands.     

Synthesis and Electrochemistry of Heterobimetallic Ruthenium/Platinum and Molybdenum/Platinum Complexes

As starting materials for heterobimetallic complexes, [RuCp(PPh(3))CO(PPh(2)H)]PF(6) and [RuCp(PPh(3))CO(eta(1)-dppm)]PF(6) were prepared from RuCp(PPh(3))(CO)Cl. In the course of preparing [RuCp(eta(2)-dppm)(eta(1)-dppm)]Cl from RuCp(Ph(3)P)(eta(1)-dppm)Cl, the new monomer RuCpCl(eta(1)-dppm)(2) was isolated. The uncommon coordination mode of the two monodentate bis(phosphines) was confirmed by X-ray crystallography [a = 11.490(1) ?, b = 14.869(2) ?, c = 15.447(2) ?, alpha = 84.63(1) degrees, beta = 70.55(1) degrees, gamma = 72.92(1) degrees, V = 2378.7(5) ?(3), d(calc) = 1.355 g cm(-)(3) (298 K), triclinic, P&onemacr;, Z = 2]. The dppm-bridged bimetallic complexes RuCp(PPh(3))Cl(&mgr;-dppm)PtCl(2), RuCpCl(&mgr;-dppm)(2)PtCl(2), and [RuCp(PPh(3))CO(&mgr;-dppm)PtCl(2)]PF(6) each exhibit electrochemistry consistent with varying degrees of metal-metal interaction. The cationic heterobimetallic complexes [Mo(CO)(3)(&mgr;-dppm)(2)Pt(H)]PF(6) and [MoCp(CO)(2)(&mgr;-PPh(2))(&mgr;-H)Pt(PPh(3))(MeCN)]PF(6) were prepared by chloride abstraction from the corresponding neutral bimetallic species and show electrochemical behavior similar to the analogous Ru/Pt complexes.     

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-).)     

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).     

Modeling the Formation of Molybdenum Oxides from Alkoxides: Crystal Structures of [Mo(4)O(4)Cl(4)(&mgr;(2)-OEt)(4)(HOEt)(2)(&mgr;(3)-O)(2)] and [PPN](+)[Et(3)NH](+)[Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-)

The reactions of the binuclear oxomolybdenum(V) complex [Cl(2)(O)Mo(&mgr;-OEt)(2)(&mgr;-HOEt)Mo(O)Cl(2)] (1) with Me(3)Si(allyl) and SbF(3) produce the compounds [Mo(6)O(6)Cl(6)(&mgr;(3)-O)(2)(&mgr;(2)-OEt)(6)(&mgr;(2)-Cl)(2)] (2) and [Mo(8)O(8)Cl(6)(&mgr;(3)-O)(4)(OH)(2)(&mgr;(2)-OH)(4)(&mgr;(2)-OEt)(4)(HOEt)(4)] (3), respectively. Treatment of 1 with the Lewis base PMe(3) affords the tetrameric complex [Mo(4)O(4)Cl(4)(&mgr;(2)-OEt)(4)(HOEt)(2)(&mgr;(3)-O)(2)] (4), which represents another link in the chain of clusters produced by the reactions of 1 and simulating the build-up of polymeric molybdenum oxides by sol-gel methods. The crystal structure of 4 has been determined [C(12)H(32)Cl(4)Mo(4)O(12), triclinic, P&onemacr;, a = 7.376(2) ?, b = 8.807(3) ?, c = 11.467(4) ?, alpha = 109.61(1) degrees, beta = 92.12(3) degrees, gamma = 103.75(2) degrees, Z = 1]. By contrast, reaction of 1 with the nitrogen base NEt(3), followed by treatment with [PPN]Cl.2H(2)O ([PPN](+) = [Ph(3)P=N=PPh(3)](+)), gives the complex [PPN](+)[Et(3)NH](+)[Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-) (6) in 90% yield. Its crystal structure [C(36)H(30)Cl(4)MoNOP(2), triclinic, Pna2(1), a = 21.470(6) ?, b = 16.765(2) ?, c = 9.6155(14) ?, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 16] includes the anion [Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-), which is a charged derivative of the species forming the gels in sol-gel processes starting from chloromolybdenum ethoxides. Furthermore, compound 1 is found to be catalytically active in esterification and dehydration reactions of alcohols.     

Model Investigations for Vanadium-Protein Interactions. Synthetic, Structural, and Physical Studies of Vanadium(III) and Oxovanadium(IV/V) Complexes with Amidate Ligands

Reaction of the amide ligand N-[2-((2-pyridylmethylene)amino)phenyl]pyridine-2-carboxamide (Hcapca) with VCl(3) affords the compound trans-[VCl(2)(capca)] (1), the first example of a vanadium(III) complex containing a vanadium-deprotonated amide nitrogen bond, while reaction of bis(pentane-2,4-dionato)oxovanadium(IV) with the related ligands N-[2-((2-phenolylmethylene)amino)phenyl]pyridine-2-carboxamide (H(2)phepca), 1-(2-hydroxybenzamido)-2-(2-pyridinecarboxamido)benzene (H(3)hypyb), and 1,2-bis(2-hydroxybenzamido)benzene (H(4)hybeb) yields the complexes [VO(phepca)] (2), Na[VO(hypyb)].2CH(3)OH (4.2CH(3)OH), and Na(2)[VO(hybeb)].3CH(3)OH (5.3CH(3)OH) respectively. The preparation of the complex {N-[2-((2-thiophenoylmethylene)amino)phenyl]pyridine-2-carboxamido}oxovanadium(IV) (3) has been achieved by reaction of N-(2-aminophenyl)pyridine-2-carboxamide and 2-mercaptobenzaldehyde with [VO(CH(3)COO)(2)](x)(). Oxidation of complex 5.3CH(3)OH with silver nitrate gives its vanadium(V) analogue (8.CH(3)OH), which is readily converted to its corresponding tetraethylammonium salt (10.CH(2)Cl(2)) by a reaction with Et(4)NCl. The crystal structures of the octahedral 1.CH(3)CN, and the square-pyramidal complexes 3, 4.CH(3)CN, 5.2CH(3)OH, and 10 were demonstrated by X-ray diffraction analysis. Crystal data are as follows: 1.CH(3)CN, C(18)H(13)Cl(2)N(4)OV.CH(3)CN M(r) = 464.23, monoclinic, P2(1)/n, a = 10.5991(7) ?, b = 13.9981(7) ?, c = 14.4021(7) ?, beta = 98.649(2)(o), V = 2112.5(3) A(3), Z = 4, R = 0.0323, and R(w) 0.0335; 3, C(19)H(13)N(3)O(2)SV, M(r) = 398.34, monoclinic, P2(1)/n, a = 12.1108(10) ?, b = 19.4439(18) ?, c = 7.2351(7) ?, beta = 103.012(3) degrees, V = 1660.0(4) ?(3), Z = 4, R = 0.0355, and R(w) = 0.0376; 4.CH(3)CN, C(19)H(12)N(3)O(4)VNa.CH(3)CN, M(r) = 461.31, monoclinic, P2(1)/c, a = 11.528(1) ?, b = 11.209(1) ?, c = 16.512(2) ?, beta = 103.928(4)(o), V = 2071.0(5) ?(3), Z = 4, R = 0.0649, and R(w) = 0.0806; 5.2CH(3)OH, C(20)H(10)N(2)O(5)VNa(2).2CH(3)OH, M(r) = 519.31, triclinic, P1, a = 12.839(1) ?, b = 8.334(1) ?, c = 12.201(1) ?, alpha = 106.492(2) degrees, beta = 105.408(2) degrees, gamma = 73.465(2) degrees, V = 1175.6(3) ?(3), Z = 2, R = 0.0894, and R(w) = 0.1043; 10, C(28)H(32)N(3)O(5)V M(r) = 541.52, monoclinic, P2(1)/c, a = 11.711(3) ?, b = 18.554(5) ?, c = 12.335(3) ?, beta = 95.947(9) degrees, V = 2666(2) ?(3), Z = 4, R = 0.0904, and R(w) = 0.0879. In addition to the synthesis and crystallographic studies, we report the optical, infrared, magnetic, and electrochemical properties of these complexes. Electron paramagnetic resonance [of oxovanadium(IV) species] and (1)H, (13)C{(1)H}, and (51)V nuclear magnetic resonance [of oxovanadium(V) complex] properties are reported as well. This study represents the first systematic study of vanadium(III), V(IV)O(2+), and V(V)O(3+) species containing a vanadium-deprotonated amide nitrogen bond.