Coordination chemistry of silver(I) with the nitrogen-bridged ligands (C(6)H(5))(2)PN(H)P(C(6)H(5))(2) and (C(6)H(5))(2)PN(CH(3))P(C(6)H(5))(2): the effect of alkylating the nitrogen bridge on ligand bridging versus chelating behavior

The coordination chemistry of silver(I) with the nitrogen-bridged ligands (C(6)H(5))(2)PN(R)P(C(6)H(5))(2) [R = H (dppa); R = CH(3) (dppma)] has been investigated by (31)P NMR and electrospray mass spectrometry (ESMS). Species observed by (31)P NMR include Ag(2)(mu-dppa)(2+), Ag(2)(mu-dppa)(2)(2+), Ag(2)(mu-dppa)(3)(2+), Ag(2)(mu-dppma)(2+), Ag(2)(mu-dppma)(2)(2+), and Ag(eta(2)-dppma)(2)(+). Species observed by ESMS at low cone voltages were Ag(2)(dppa)(2)(2+), Ag(2)(dppa)(3)(2+), Ag(2)(dppma)(2)(2+), and Ag(dppma)(2)(+). (C(6)H(5))(2)PN(CH(3))P(C(6)H(5))(2) showed a strong tendency to chelate, while (C(6)H(5))(2)PN(H)P(C(6)H(5))(2) preferred to bridge. Differences in the bridging versus chelating behavior of the ligands are assigned to the Thorpe-Ingold effect, where the methyl group on nitrogen sterically interacts with the phenyl groups on phosphorus. The crystal structure of the three-coordinate dinuclear silver(I) complex (Ag(2)[(C(6)H(5))(2)PN(H)P(C(6)H(5))(2)](3))(BF(4))(2) has been determined. Bond distances include Ag-Ag = 2.812(1) A, Ag(1)-P(av) = 2.492(3) A, and Ag(2)-P(av) = 2.509(3) A. The compound crystallizes in the monoclinic space group Cc at 294 K, with a = 18.102(4)(o), Z = 4, V = 7261(3) A(3), R = 0.0503, and R(W) = 0.0670.     

Syntheses, structural characterization and properties of transition metal complexes of 5,5'-(1,4-phenylene)bis(1H-tetrazole) (H(2)bdt), 5',5'-(1,1'-biphenyl)-4,4'-diylbis(1H-tetrazole) (H(2)dbdt) and 5,5',5'-(1,3,5-phenylene)tris(1H-tetrazole) (H(3)btt)

The hydrothermal chemistry of a variety of M(II)SO(4) salts with the tetrazole (Ht) ligands 5,5'-(1,4-phenylene)bis(1H-tetrazole) (H(2)bdt), 5',5'-(1,1'-biphenyl)4,4'-diylbis(1H-tetrazole) (H(2)dbdt) and 5,5',5'-(1,3,5-phenylene)tris(1H-tetrazole) (H(3)btt) was investigated. In the case of Co(II), three phases were isolated, two of which incorporated sulfate: [Co(5)F(2)(dbdt)(4)(H(2)O)(6)]·2H(2)O (1·2H(2)O), [Co(4)(OH)(2)(SO(4))(bdt)(2)(H(2)O)(4)] (2) and [Co(3)(OH)(SO(4))(btt)(H(2)O)(4)]·3H(2)O (3·3H(2)O). The structures are three-dimensional and consist of cluster-based secondary building units: the pentanuclear {Co(5)F(2)(tetrazolate)(8)(H(2)O)(6)}, the tetranuclear {Co(4)(OH)(2)(SO(4))(2)(tetrazolate)(6)}(4-), and the trinuclear {Co(3)(μ(3)-OH)(SO(4))(2) (tetrazolate)(3)}(2-) for 1, 2, and 3, respectively. The Ni(II) analogue [Ni(2)(H(0.67)bdt)(3)]·10.5H(2)O (4·10.5H(2)O) is isomorphous with a fourth cobalt phase, the previously reported [Co(2)(H(0.67)bat)(3)]·20H(2)O and exhibits a {M(tetrazolate)(3/2)}(∞) chain as the fundamental building block. The dense three-dimensional structure of [Zn(bdt)] (5) consists of {ZnN(4)}tetrahedra linked through bdt ligands bonding through N1,N3 donors at either tetrazolate terminus. In contrast to the hydrothermal synthesis of 1-5, the Cd(II) material (Me(2)NH(2))(3)[Cd(12)Cl(3)(btt)(8)(DMF)(12)]·xDMF·yMeOH (DMF = dimethylformamide; x = ca. 12, y = ca. 5) was prepared in DMF/methanol. The structure is constructed from the linking of {Cd(4)Cl(tetrazolate)(8)(DMF)(4)}(1-) secondary building units to produce an open-framework material exhibiting 66.5% void volume. The magnetic properties of the Co(II) series are reflective of the structural building units.     

Selenolate gold complexes with aurophilic Au(I)-Au(I) and Au(I)-Au(III) interactions

The gold(I) selenolate compound [Au(2)(SePh)(2)(mu-dppf)] (dppf = 1,1'-bis(diphenylphosphino)ferrocene) has been prepared by reaction of [Au(2)Cl(2)(mu-dppf)] with PhSeSiMe(3) in a molar ratio 1:2. This complex reacts with gold(I) or gold(III) derivatives to give polynuclear gold(I)-gold(I) or gold(I)-gold(III) complexes of the type [Au(4)(mu-SePh)(2)(PPh(3))(2)(mu-dppf)](OTf)(2), [Au(3)(C(6)F(5))(3)(mu-SePh)(2)(mu-dppf)], or [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)], with bridging selenolate ligands. The reaction of [Au(2)(SePh)(2)(mu-dppf)] with 1 equiv of AgOTf leads to the formation of the insoluble Ag(SePh) and the compound [Au(2)(mu-SePh)(mu-dppf)]OTf. The complexes [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)] and [Au(2)(mu-SePh)(mu-dppf)]OTf (two different solvates) have been characterized by X-ray diffraction studies and show the presence of weak gold(I)-gold(III) interactions in the former and intra- and intermolecular gold(I)-gold(I) inter-actions in the later.     

Tris(dimethylamino)oxosulfonium difluorotrimethylsilicate, (Me(2)N)(3)SO(+)Me(3)SiF(2)(-) (TAOS Fluoride)

In the OSF(4)/Me(2)NSiMe(3) system besides the long known Me(2)NS(O)F(3) only the trisubstituted derivative is isolated as (Me(2)N)(3)SO(+)Me(3)SiF(2)(-) (3). Similar to (Me(2)N)(3)S(+)Me(3)SiF(2)(-) compound 3 is an excellent fluoride ion donor. With AsF(5) and HF the corresponding hexafluoroarsenate (Me(2)N)(3)SO(+)AsF(6)(-) (4) and the hydrogen bifluoride (Me(2)N)(3)SO(+)HF(2)(-) (5) are formed in almost quantitative yield. X-ray structure determinations of 3-5 surprisingly showed two different types of structures for the cation. In 3 and 5 this cation has C(3) symmetry, while in the hexafluoroarsenate 4 a (Me(2)N)(3)S(+)-like structure with C(s)() symmetry is determined. The experimental results for (Me(2)N)(3)SO(+) and (Me(2)N)(3)S(+) are compared with theoretical calculations for these cations and their isoelectronic neutral counterparts, the phosphorus amides (Me(2)N)(3)PO and (Me(2)N)(3)P, respectively.     

Synthesis and reactivity of bis(imido) uranium(VI) cyclopentadienyl complexes

The bis(imido) uranium(VI)-C(5)H(5) and -C(5)Me(5) complexes (C(5)H(5))(2)U(N(t)Bu)(2), (C(5)Me(5))(2)U(N(t)Bu)(2), (C(5)H(5))U(N(t)Bu)(2)(I)(dmpe), and (C(5)H(5))(2)U(N(t)Bu)(2)(dmpe) can be synthesized from reactions between U(N(t)Bu)(2)(I)(2)(L)(x) (L=THF, x=2; L=dmpe, x=1) and Na(C(5)R(5)) (R=H, Me); these complexes represent the first structurally characterized C(5)H(5)-compounds of uranium(VI) and they further highlight the differences between UO(2)(2+) and the bis(imido) fragment.     

Coordinatively unsaturated W(IV)-bis(pyridine) complexes, a reactive source of W(IV)

Addition of 2 equiv of a sigma-donor ligand (L = pyridine, 4-picoline, or quinoline) to complexes of the type [W(NPh)(eta(4)-arene)(o-(Me3SiN)2C6H4)] (arene = CH3CH2C6H5 (3), CH3CH2CH2C6H5 (4)) gave the W(IV)L2 compounds, [W(NPh)(o-(Me3SiN)2C6H4)(C5H5N)2] (5), [W(NPh)(o-(Me3SiN)2C6H4)(p-C6H7N)2] (6), and [W(NPh)(o-(Me3SiN)2C6H4)(C9H7N)2] (7). Synthesis of compounds 5 and 6 by Na degrees reduction of [W(NPh)(o-(Me3SiN)2C6H4)Cl2] in the presence of 3 equiv of L (L = 5, pyridine or 6, 4-picoline) is also presented. Compounds 5, 6, and 7 display hindered rotation of the donor ligands about the W-N bonds, resulting from a steric interaction with the Me3Si groups of the diamide ligand. The coordinative unsaturation of 5 and 6 has also been explored. Compounds 5 and 6 readily react with either CO and PMe3 to generated the six coordinate complexes [W(NPh)(o-(Me3SiN)2C6H4)(C5H5N)2(CO)] (8a), [W(NPh)(o-(Me3SiN)2C6H4)(C6H7N)2(CO)] (8b), [W(NPh)(o-(Me3SiN)2C6H4)(C5H5N)(PMe3)2] (10a), and [W(NPh)(o-(Me3SiN)2C6H4)(C6H7N)(PMe3)2] (10b), respectively.     

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.     

Heavy-metal aromatic and conjugated species: rings, oligomers, and chains of tin in Li(9)(-)(x)EuSn(6+)(x), Li(9)(-)(x)CaSn(6+)(x), Li(5)Ca(7)Sn(11), Li(6)Eu(5)Sn(9), LiMgEu(2)Sn(3), and LiMgSr(2)Sn(3)

The title compounds were synthesized from the elements by heating the corresponding mixtures at high temperature. Their structures were determined from single-crystal X-ray diffraction. Li(9)(-)(x)()EuSn(6+)(x)(), Li(9)(-)(x)()CaSn(6+)(x)(), Li(5)Ca(7)Sn(11), and Li(6)Eu(5)Sn(9) contain columns of stacked aromatic pentagons of Sn(5)(6)(-) that are analogous to the cyclopentadienyl anion C(5)H(5)(-). The pentagons are separated with Ca(2+) or Eu(2+) in the columns and resemble a polymeric metallocene. In addition to the columns, the isostructural Li(9)(-)(x)()EuSn(6+)(x)() and Li(9)(-)(x)()CaSn(6+)(x)() contain isolated tin atoms and bent tin trimers while Li(5)Ca(7)Sn(11) and Li(6)Eu(5)Sn(9) contain flat zigzag hexamers and flat zigzag infinite chains of tin, respectively. The isostructural LiMgEu(2)Sn(3) and LiMgSr(2)Sn(3) do not contain columns of pentagons but only flat zigzag infinite chains of tin. The aromaticity of the pentagons and the conjugation of the pi-systems of the hexamers and the infinite chains are discussed. The title compounds are also characterized by magnetic and conductivity measurements.     

Cyanide-bridged linkage isomers with catecholateruthenium(II) centres bound to Mn(I) or M(alkyne) units

Two series of stable cyanide-bridged linkage isomers, namely [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-XY)MnL(NO)(eta-C5Me5)] (XY = CN or NC, L = CNBu(t) or CNXyl) and [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC-CPh)Tp'] {M = Mo or W, L = PPh3 or P(OPh)3, Tp' = hydrotris(3,5-dimethylpyrazolyl)borate} have been synthesised; pairs of isomers are distinguishable by IR spectroscopy and cyclic voltammetry. The molecular structure of [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-NC)Mo(CO)(PhC-CPh)Tp'] has the catecholate-bound ruthenium atom cyanide-bridged to a Mo(CO)(PhC[triple band]CPh)Tp' unit in which the alkyne acts as a four-electron donor; the alignment of the alkyne relative to the Mo-CO vector suggests the fragment (CN)Ru(CO)2(PPh3)(o-O2C6Cl4) acts as a pi-acceptor ligand. The complexes [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-XY)Mn(NO)L(eta-C5Me5)] undergo three sequential one-electron oxidation processes with the first and third assigned to oxidation of the ruthenium-bound o-O2C6Cl4 ligand; the second corresponds to oxidation of Mn(I) to Mn(n). The complexes [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC[triple band]CPh)Tp'] are also first oxidised at the catecholate ligand; the second oxidation, and one-electron reduction, are based on the M(CO)(PhC[triple band]CPh)Tp' fragment. Chemical oxidation of [(o-O,C6Cl4)(Ph3P)(OC)2Ru(mu-XY)MnL(NO)(eta-C5Me5)] with [Fe(eta-C5H4COMe)(eta-C5H5)][BF4], or of [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC[triple band]CPh)Tp'] with AgBF4, gave the paramagnetic monocations [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-XY)MnL(NO)(eta-C5Me5)]+ and [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC[triple band]CPh)Tp']+, the ESR spectra of which are consistent with ruthenium-bound semiquinone ligands. Linkage isomers are distinguishable by the magnitude of the 31P hyperfine coupling constant; complexes with N-bound Ru(o-O2C6Cl4) units also show small hyperfine coupling to the nitrogen atom of the cyanide bridge.     

H(2) activation and hydride transfer to olefins by al(c(6) f(5) )(3) -based frustrated lewis pairs

Frustrated delivery: Frustrated Lewis pairs derived from tBu(3) P and Al(C(6) F(5) )(3) activate H(2) to give [tBu(3) PH][(μ-H)(Al(C(6) F(5) )(3) )(2) ], which reacts with unactivated olefins to give RAl(C(6) F(5) )(2) (R=Et or Cy) and [tBu(3) PH][Al(C(6) F(5) )(4) ]. The proposed mechanism involves olefin activation by aluminum, which is supported by the isolation of the cyclohexene complex [Al(C(6) F(5) )(3) ?(C(6) H(10) )].     

Syntheses,reactivity, and crystal structures of molybdenum complexes with pyridine-2-thionate (pyS)-containing ligands: crystal structures of [Mo(eta(3)-C(3)H(5))(CO)(2)](2)(mu-eta(1),eta(2)-pyS)(2), exo-[Mo(eta(3)-C(3)H(5))(CO)(eta(2)-pyS)(eta(2)-dppe)], [Mo(CO)(3)(eta(1)-SC(5)H(4)NH)(eta(2)-dppm)], and [Mo(CO)(eta(2)-pyS)(2)(eta(2)-dppm)

The doubly bridged pyridine-2-thionate (pyS) dimolybdenum complex [Mo(eta(3)-C(3)H(5))(CO)(2)](2)(mu-eta(1),eta(2)-pyS)(2) (1) is accessible by the reaction of [Mo(eta(3)-C(3)H(5))(CO)(2)(CH(3)CN)(2)Br] with pySK in methanol at room temperature. Complex 1 reacts with piperidine in acetonitrile to give the complex [Mo(eta(3)-C(3)H(5))(CO)(2)(eta(2)-pyS)(C(5)H(10)NH)] (2). Treatment of 1 with 1,10-phenanthroline (phen) results in the formation of complex [Mo(eta(3)-C(3)H(5))(CO)(2)(eta(1)-pyS)(phen)] (3), in which the pyS ligand is coordinated to Mo through the sulfur atom. Four conformational isomers, endo,exo-complexes [Mo(eta(3)-C(3)H(5))(CO)(eta(2)-pyS)(eta(2)-diphos)] (diphos = dppm, 4a-4d; dppe, 5a-5d), are accessible by the reactions of 1 with dppm and dppe in refluxing acetonitrile. Homonuclear shift-correlated 2-D (31)P((1)H)-(31)P((1)H) NMR experiments of the mixtures 4a-4d have been employed to elucidate the four stereoisomers. The reaction of 4 and pySK or [Mo(CO)(3)(eta(1)-SC(5)H(4)NH)(eta(2)-dppm)] (6) and O(2) affords allyl-displaced seven-coordinate bis(pyridine-2-thionate) complex [Mo(CO)(eta(2)-pyS)(2)(eta(2)-dppm)] (7). All of the complexes are identified by spectroscopic methods, and complexes 1, 5d, 6, and 7 are determined by single-crystal X-ray diffraction. Complexes 1 and 5d crystallize in the orthorhombic space groups Pbcn and Pbca with Z = 4 and 8, respectively, whereas 6 belongs to the monoclinic space group C2/c with Z = 8 and 7 belongs to the triclinic space group Ponemacr; with Z = 2. The cell dimensions are as follows: for 1, a = 8.3128(1) A, b = 16.1704(2) A, c = 16.6140(2) A; for 5d, a = 17.8309(10) A, b = 17.3324(10) A, c = 20.3716(11) A; for 6, a = 18.618(4) A, b = 16.062(2) A, c = 27.456(6) A, beta = 96.31(3) degrees; for 7, a = 9.1660(2) A, b = 12.0854(3) A, c = 15.9478(4) A, alpha = 78.4811(10) degrees, beta = 80.3894(10) degrees, gamma = 68.7089(11) degrees.     

Phosphaallyl complexes of Ru(II) derived from dicyclohexylvinylphosphine (DCVP)

The complexes [(eta5-RC5H4)Ru(CH3CN)3]PF6(R = H, CH3) react with DCVP (DCVP = Cy2PCH=CH2) at room temperature to produce the phosphaallyl complexes [(eta5-C5H5)Ru(eta1-DCVP)(eta3-DCVP)]PF6 and [(eta5-MeC5H4)Ru(eta1-DCVP)(eta3-DCVP)]PF6. Both compounds react with a variety of two-electron donor ligands displacing the coordinated vinyl moiety. In contrast, we failed to prepare the phosphaallyl complexes [(eta5-C5Me5)Ru(eta1-DCVP)(eta3-DCVP)]PF6, [(eta5-MeC5H4)Ru(CO)(eta3-DCVP)]PF6 and [(eta5-C5Me5)Ru(CO)(eta3-DPVP)]PF6(DPVP = Ph2PCH=CH2).The compounds [(eta5-MeC5H4)Ru(CO)(CH3CN)(DPVP)]PF6 and [(eta5-C5Me5)Ru(CO)(CH3CN)(DPVP)]PF6 react with DMPP (3,4-dimethyl-1-phenylphosphole) to undergo [4 + 2] Diels-Alder cycloaddition reactions at elevated temperature. Attempts at ruthenium catalyzed hydration of phenylacetylene produced neither acetophenone nor phenylacetaldehyde but rather dimers and trimers of phenylacetylene. The structures of the complexes described herein have been deduced from elemental analyses, infrared spectroscopy, 1H, 13C{1H}, 31P{1H} NMR spectroscopy and in several cases by X-ray crystallography.     

Structural isomers of aryl-substituted eta(3)-propargyl complexes: eta(2)-1-Metalla(methylene)cyclopropene and eta(3)-benzyl complexes

Hydride abstraction from C(5)Me(5)(CO)(2)Re(eta(2)-PhC triple bond CCH(2)Ph) (1) gave a 3:1 mixture of eta(3)-propargyl complex [C(5)Me(5)(CO)(2)Re(eta(3)-PhCH-C triple bond CPh)][BF(4)] (5) and eta(2)-1-metalla(methylene)cyclopropene complex [C(5)Me(5)(CO)(2)Re(eta(2)-PhC-C=CHPh)][BF(4)] (6). Observation of the eta(2)-isomer requires 1,3-diaryl substitution and is favored by electron-donating substituents on the C(3)-aryl ring. Interconversion of eta(3)-propargyl and eta(2)-1-metalla(methylene)cyclopropene complexes is very rapid and results in coalescence of Cp (1)H NMR resonances at about -50 degrees C. Protonation of the alkynyl carbene complex C(5)Me(5)(CO)(2)Re=C(Ph)C triple bond CPh (22) gave a third isomer, the eta(3)-benzyl complex [C(5)Me(5)(CO)(2)Re[eta(3)(alpha,1,2)-endo,syn-C(6)H(5)CH(C triple bond CC(6)H(5))]][BF(4)] (23) along with small amounts of the isomeric complexes 5 and 6. While 5 and 6 are in rapid equilibrium, there is no equilibration of the eta(3)-benzyl isomer 23 with 5 and 6.     

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)).     

Insertion reactions of hydridonitrosyltetrakis(trimethylphosphine) tungsten(0)

[W(H)(NO)(PMe3)4] (1) was prepared by the reaction of [W(Cl)(NO)(PMe3)4] with NaBH4 in the presence of PMe3. The insertion of acetophenone, benzophenone and acetone into the W-H bond of 1 afforded the corresponding alkoxide complexes [W(NO)(PMe3)4(OCHR1R2)](R1 = R2 = Me (2); R1 = Me, R2 = Ph (3); R1 = R2 = Ph (4)), which were however thermally unstable. Insertion of CO2 into the W-H bond of yields the formato-O complex trans-W(NO)(OCHO)(PMe3)4 (5). Reaction of trans-W(NO)(H)(PMe3)4 with CO led to the formation of mer-W(CO)(NO)(H)(PMe3)3 (6) and not the formyl complex W(NO)(CHO)(PMe3)4. Insertion of Fe(CO)(5), Re2(CO)10 and Mn2(CO)10 into trans-W(NO)(H)(PMe3)4 resulted in the formation of trans-W(NO)(PMe3)4(mu-OCH)Fe(CO)4 (7), trans-W(NO)(PMe3)4(mu-OCH)Re2(CO)9 (8) and trans-W(NO)(PMe3)4(mu-OCH)Mn2(CO)9 (9). For Re2(CO)10, an equilibrium was established and the thermodynamic data of the equilibrium reaction have been determined by a variable-temperature NMR experiments (K(298K)= 104 L mol(-1), DeltaH=-37 kJ mol(-1), DeltaS =-86 J K(-1) mol(-1)). Both compounds 7 and 8 were separated in analytically pure form. Complex 9 decomposed slowly into some yet unidentified compounds at room temperature. Insertion of imines into the W-H bond of 1 was also additionally studied. For the reactions of the imines PhCH=NPh, Ph(Me)C=NPh, C6H5CH=NCH2C6H5, and (C6H5)2C=NH with only decomposition products were observed. However, the insertion of C10H7N=CHC6H5 into the W-H bond of led to loss of one PMe3 ligand and at the same time a strong agostic interaction (C17-H...W), which was followed by an oxidative addition of the C-H bond to the tungsten center giving the complex [W(NO)(H)(PMe3)3(C10H6NCH2Ph)] (10). The structures of compounds 1, 4, 7, 8 and 10 were studied by single-crystal X-ray diffraction.     

Addition of Pt(PBu(t)(3)) groups to Ru(5)(CO)(12)(eta(6)-C(6)H(6))(mu(5)-C). Synthesis, structures, and dynamical activity

The reaction of Ru(5)(CO)(12)(eta(6)-C(6)H(6))(mu(5)-C), 7, with Pt(PBu(t)(3))(2) yielded two products Ru(5)(CO)(12)(eta(6)-C(6)H(6))(mu(6)-C)[Pt(PBu(t)(3))], 8, and Ru(5)(CO)(12)(eta(6)-C(6)H(6))(mu(6)-C)[Pt(PBu(t)(3))](2), 9. Compound 8 contains a Ru(5)Pt metal core in an open octahedral structure. In solution, 8 exists as a mixture of two isomers that interconvert rapidly on the NMR time scale at 20 degrees C, DeltaH() = 7.1(1) kcal mol(-1), DeltaS() = -5.1(6) cal mol(-)(1) K(-)(1), and DeltaG(298)(#) = 8.6(3) kcal mol(-1). Compound 9 is structurally similar to 8, but has an additional Pt(PBu(t)(3)) group bridging an Ru-Ru edge of the cluster. The two Pt(PBu(t)(3)) groups in 9 rapidly exchange on the NMR time scale at 70 degrees C, DeltaH(#) = 9.2(3) kcal mol(-)(1), DeltaS(#) = -5(1) cal mol(-)(1) K(-)(1), and DeltaG(298)(#) = 10.7(7) kcal mol(-1). Compound 8 reacts with hydrogen to give the dihydrido complex Ru(5)(CO)(11)(eta(6)-C(6)H(6))(mu(6)-C)[Pt(PBu(t)(3))](mu-H)(2), 10, in 59% yield. This compound consists of a closed Ru(5)Pt octahedron with two hydride ligands bridging two of the four Pt-Ru bonds.     

Syntheses and reactivity of the diselenido molybdenum-manganese complex CpMoMn(CO)5(mu-Se2)

Reaction of CpMoMn(CO)(8) with elemental selenium and Me(3)NO in the absence of light yielded the diselenido complex CpMoMn(CO)(5)(mu-Se(2)), 2. Compound 2 contains a bridging diselenido ligand lying perpendicular to the Mo-Mn bond, Mo-Mn = 2.8421(10) A. In the presence of room light, the reaction yielded the tetranuclear metal complex Cp(2)Mo(2)Mn(2)(CO)(7)(mu(3)-Se)(4), 3 (36% yield), and 2 (7% yield). Compound 2 reacted with ethylene to yield the ethanediselenato complex CpMoMn(CO)(5)(mu-SeCH(2)CH(2)Se), 4, by insertion of ethylene into the Se-Se bond. Compound 2 also reacted with (PPh(3))(2)Pt(PhC(2)Ph) and CpCo(CO)(2) to yield the complexes CpMoMnPt(PPh(3))(2)(CO)(5)(mu(3)-Se)(2), 5, and Cp(2)CoMoMn(CO)(5)(mu(3)-Se)(2), 6, respectively, by insertion of the metal groupings CpCo and Pt(PPh(3))(2) into the Se-Se bond of 2. The oxo compound Cp(2)CoMo(O)Mn(CO)(5)(mu(3)-Se)(2), 7, was obtained from 6 by decarbonylation at molybdenum by using Me(3)NO. The molecular structures of the complexes 2-7 were established by single-crystal X-ray diffraction analyses.     

Syntheses and structural characterizations of endo-eta(1)-, exo-eta(1)-, eta(4)-, eta(5)-, and eta(6)-metallaphosphamonocarbaborane complexes derived from a versatile new polyborane ligand: exo-6-R-arachno-6,7-PCB(8)H(12)

Deprotonation of the phosphamonocarbaborane, exo-6-R-arachno-6,7-PCB(8)H(12) (R = Ph 1a or Me 1b), yields exo-6-R-arachno-6,7-PCB(8)H(11)(-), which when reacted with appropriate transition-metal reagents affords new metallaphosphamonocarbaborane complexes in which the metals adopt endo-eta(1), exo-eta(1), eta(4), eta(5), or eta(6) coordination geometries bonded to the formal R-arachno-PCB(8)H(11)(-), R-arachno-PCB(8)H(10)(2-), R-arachno-PCB(8)H(9)(3-), or R-nido-PCB(8)H(9)(-) ligands. The reaction of exo-6-(C(6)H(5))-arachno-6,7-PCB(8)H(11)(-) (1a-) with Mn(CO)(5)Br generated the eta(1)-sigma product exo-6-[Mn(CO)(5)]-endo-6-(C(6)H(5))-arachno-6,7-PCB(8)H(11) (2) having the [Mn(CO)(5)] fragment in the thermodynamically favored exo position at the P6 cage atom. On the other hand, reaction of 1a- with (eta(5)-C(5)H(5))Fe(CO)(2)I resulted in the formation of two products, an eta(1)-sigma complex endo-6-[(eta(5)-C(5)H(5))Fe(CO)(2)]-exo-6-(C(6)H(5))-arachno-6,7-PCB(8)H(11) (3) having the (eta(5)-C(5)H(5))Fe(CO)(2) fragment attached at the endo-P6 position and an eta(6)-closo complex, 1-(eta(5)-C(5)H(5))-2-(C(6)H(5))-closo-1,2,3-FePCB(8)H(9) (4a). Rearrangement of the endo-compound 3 to its exo-isomer 5 was observed upon photolysis of 3. Synthesis of the methyl analogue of 4a, 1-(eta(5)-C(5)H(5))-2-CH(3)-closo-1,2,3-FePCB(8)H(9) (4b), along with a double-insertion product, 1-CH(3)-2,3-(eta(5)-C(5)H(5))(2)-2,3,1,7-Fe(2)PCB(8)H(9) (6), containing two iron atoms eta(5)-coordinated to a formal R-arachno-PCB(8)H(9)(3-), was achieved by reaction of exo-6-CH(3)-arachno-6,7-PCB(8)H(11)(-) (1b-) with FeCl(2) and Na(+)C(5)H(5)(-). Complexes 4a and 4b can be considered ferrocene analogues, in which an Fe(II) is sandwiched between C(5)H(5)(-) and 6-R-nido-6,9-PCB(8)H(9)(-) anions. Reaction of exo-6-(C(6)H(5))-arachno-6,7-PCB(8)H(11)(-) (1a-) with cis-dichlorobis(triphenylphosphine)platinum (II) afforded two compounds, an eta(1)-sigma complex with the metal fragment again in the endo-P6 position, endo-6-[cis-(Ph(3)P)(2)PtCl]-exo-6-(C(6)H(5))-arachno-6,7-PCB(8)H(11) (7) and an eta(4)-complex, 7-(C(6)H(5))-11-(Ph(3)P)(2)-nido-11,7,8-PtPCB(8)H(10) (8) containing the formal R-arachno-PCB(8)H(10)(2)(-) anion. The structures of compounds 2, 3, 4a, 4b, 6, 7, and 8 were crystallographically confirmed.     

Reaction of nido-7,8-C(2)B(9)H(13) with Dicobalt Octacarbonyl: Crystal Structures of the Complexes [Co(2)(CO)(2)(eta(5)-7,8-C(2)B(9)H(11))(2)], [Co(2)(CO)(PMe(2)Ph)(eta(5)-7,8-C(2)B(9)H(11))(2)], and [CoCl(PMe(2)Ph)(2)(eta(5)-7,8-C(2)B(9)H(11))

The compounds [Co(2)(CO)(8)] and nido-7,8-C(2)B(9)H(13) react in CH(2)Cl(2) to give a complex mixture of products consisting primarily of two isomers of the dicobalt species [Co(2)(CO)(2)(eta(5)-7,8-C(2)B(9)H(11))(2)] (1), together with small amounts of a mononuclear cobalt compound [Co(CO)(2)(eta(5)-10-CO-7,8-C(2)B(9)H(10))] (5) and a charge-compensated carborane nido-9-CO-7,8-C(2)B(9)H(11) (6). In solution, isomers 1a and 1b slowly equilibrate. However, column chromatography allows a clean separation of 1a from the mixture, and a single-crystal X-ray diffraction study revealed that each metal atom is ligated by a terminal CO molecule and in a pentahapto manner by a nido-C(2)B(9)H(11) cage framework. The two Co(CO)(eta(5)-7,8-C(2)B(9)H(11)) units are linked by a Co-Co bond [2.503(2) ?], which is supported by two three-center two-electron B-H right harpoon-up Co bonds. The latter employ B-H vertices in each cage which lie in alpha-sites with respect to the carbons in the CCBBB rings bonded to cobalt. Addition of PMe(2)Ph to a CH(2)Cl(2) solution of a mixture of the isomers 1, enriched in 1b, gave isomers of formulation [Co(2)(CO)(PMe(2)Ph)(eta(5)-7,8-C(2)B(9)H(11))(2)] (2). Crystals of one isomer were suitable for X-ray diffraction. The molecule 2a has a structure similar to that of 1a but differs in that whereas one B-H right harpoon-up Co bridge involves a boron atom in an alpha-site of a CCBBB ring coordinated to cobalt, the other uses a boron atom in the beta-site. Reaction between 1b and an excess of PMe(2)Ph in CH(2)Cl(2) gave the complex [CoCl(PMe(2)Ph)(2)(eta(5)-7,8-C(2)B(9)H(11))] (3), the structure of which was established by X-ray diffraction. Experiments indicated that 3 was formed through a paramagnetic Co(II) species of formulation [Co(PMe(2)Ph)(2)(eta(5)-7,8-C(2)B(9)H(11))]. Addition of 2 molar equiv of CNBu(t) to solutions of either 1a or 1b gave a mixture of two isomers of the complex [Co(2)(CNBu(t))(2)(eta(5)-7,8-C(2)B(9)H(11))(2)] (4). NMR data for the new compounds are reported and discussed.     

1-Borabenzonitrile (B-cyanoboratabenzene)

The reaction of 1-chloro-2-(trimethylsilyl)-1-boracyclohexa-2,5-diene with [(n)Bu(4)N]C≡N provides the 1-borabenzonitrile salt [(n)Bu(4)N][C(5)H(5)BC≡N] which in turn reacts with [Ru(4)(μ-Cl)(4)(η-C(5)Me(5))(4)] to afford the sandwich complex [Ru(η(6)-C(5)H(5)BC≡N)(η-C(5)Me(5))]. The bonding of 1-borabenzonitrile is discussed with recourse to crystallographic data for [(n)Bu(4)N][C(5)H(5)BC≡N] and [Ru(η(6)-C(5)H(5)BC≡N)(η-C(5)Me(5))].