New rhenium-tin cluster adds palladium phosphine groups across Re-Sn bonds

The new rhenium-tin complex Re2(CO)8(mu-SnPh2)2, 1 was obtained in 52% yield from the reaction of Re2(CO)8(mu-H)[mu-C(H)C(H)Bu] with Ph3SnH. Compound 1 contains two SnPh2 groups bridging a long Re-Re single bond, Re-Re = 3.1971(4) A [3.1902(4) A], Re-Sn = 2.7429(4) A [2.7445(4) A], and 2.7675(4) [2.7682(5) A]. A bis-Pd(PBut3) adduct of 1, Pd2Re2(CO)8(mu-SnPh2)2(PBut3)2, 2 was obtained from the reaction of 1 with Pd(PBut3)2. Compound 2 contains Pd(PBut3) groups bridging two of its four Re-Sn bonds. The Re-Re bond and the unbridged Re-Sn bonds in 2 are significantly longer than those in 1, 3.245(1) A and 2.8167(14) A, respectively. Fenske-Hall molecular orbital calculations on 1 and 2 have been performed to explain the metal-metal bonding in these unusual mixed-metal polynuclear metal complexes.     

Bimetallic clusters of iron with palladium and platinum. Synthesis and structures of Fe2(CO)9[M(PBu(t)3)]2 (M = Pd or Pt) and Fe2(CO)8[Pt(PBu(t)3)]2(mu-H)2

The reaction of Fe2(CO)9 with Pd(PBu(t)3)2 and Pt(PBu(t)3)2 yielded the Fe-Pd and Fe-Pt cluster complexes Fe2(CO)9[M(PBu(t)3)]2, M = Pd (8) or Pt (9). The structures of 8 and 9 are analogous and consist of nearly planar butterfly clusters of two palladium/platinum atoms in the wing-tip positions and two mutually bonded iron atoms, Fe-Fe = 2.9582(11) A in 8 and 2.9100 (9) A in 9. Compound 8 decomposes to form the mononuclear iron compound Fe(CO)4(PBu(t)3) (11) when heated at 68 degrees C. The reaction of Pt(PBu(t)3)2 with Fe2(CO)9 in the presence of hydrogen at 127 degrees C yielded the dihydrido complex Fe2(CO)8[Pt(PBu(t)3)]2(mu-H)2 (10). Compound 10 contains a closed Fe2Pt2 tetrahedral cluster with hydrido ligands bridging two of the Fe-Pt bonds. Compounds 8, 9, and 10 were structurally characterized crystallographically.     

Activation of metal hydride complexes by tri-tert-butylphosphine-platinum and -palladium groups

The compounds HM(CO)4SnPh3, M = Os (10), Ru (11) are activated in the presence of Pt(PBut3)2 and Pd(PBu(t)3)2 toward the insertion of PhC2H into the M-H bond. The compounds PtOs(CO)4(SnPh3)(PBu(t)3)[mu-HCC(H)Ph], 12, and PtOs(CO)4(SnPh3)(PBu(t)3)[mu-H2CCPh], 13, were obtained from the reaction of 10 with PhC2H in the presence of Pt(PBu(t)3)2. Compounds 12 and 13 are isomers containing alkenyl ligands formed by the insertion of the PhC2H molecule into the Os-H bond at both the substituted and unsubstituted carbon atoms of the alkyne. Both compounds contain a Pt(PBu(t)3) group that is bonded to the osmium atom and a bridging alkenyl ligand that is pi-bonded to the osmium atom. The reaction of 11 with PhC2H in the presence of Pt(PBu(t)3)2 yielded the products PtRu(CO)4(SnPh3)(PBu(t)3)[mu-HC2(H)Ph], 14, and PtRu(CO)4(SnPh3)(PBut3)[mu-H2C2Ph], 15, which are also isomers similar to 12 and 13. The reaction of 11 with PhC2H in the presence of Pd(PBu(t)3)2 yielded the product PdRu(CO)4(SnPh3)(PBu(t)3)[mu-H2C2Ph], 16. Compound 16 contains a Pd(PBu(t)3) group bonded to the ruthenium atom and a bridging H2C2Ph ligand that is pi-bonded to the palladium atom. Compound 10 reacted with Pt(PBu(t)3)2 in the absence of PhC2H to yield the compound PtOs(CO)4(SnPh3)(PBu(t)3)(mu-H), 17. Compound 17 is a Pt(PBu(t)3) adduct of 10. It contains a Pt-Os bond with a bridging hydrido ligand. Compound 17 reacted with PhC2H to yield 12. Compound 12 reacted with PhC2H to yield the compound PtOs(CO)3(SnPh3)(PBu(t)3)[mu-HCC(Ph)C(H)C(H)Ph], 18. Compound 18 contains a bridging 2,4-diphenylbutadienyl ligand, HCC(Ph)C(H)C(H)Ph, that is pi-bonded to the osmium atom and sigma-bonded to the platinum atom. Fenkse-Hall molecular orbitals of 17 were calculated. The LUMO of 17 exhibits an empty orbital on the platinum atom that appears to be the most likely site for PhC2H addition prior to its insertion into the Os-H bond.     

Mechanism of protonation of [Pt(3)(mu-PBu(t)(2))3(H)(CO)2], yielding the hydride-bridged [Pt(3)(mu-PBu(t)(2))2(mu-H)(PBu(t)(2)H)(CO)2]OTf (Tf=CF(3)SO(2)), and the spectroscopic and theoretical characterization of a kinetic intermediate

The reaction of the Pt(I)Pt(I)Pt(II) triangulo cluster Pt(3)(micro-PBu(t)()(2))(3)(H)(CO)(2) (1) with TfOH (Tf = CF(3)SO(2)) affords the hydride-bridged cationic derivative [Pt(3)(mu-PBu(t)()(2))(2)(mu-H)(PBu(t)()(2)H)(CO)(2)]OTf (2). With TfOD the reaction gives selectively [Pt(3)(mu-PBu(t)(2))(2)(mu-D)(PBu(t)(2)H)(CO)(2)]OTf (2-D(1)), implying that the proton is transferred to a metal center while a P-H bond is formed by the reductive coupling of one of the bridging phosphides and the terminal hydride ligand of the reagent. The reaction proceeds through the formation of a thermally unstable kinetic intermediate which was characterized at low temperatures, and was suggested to be the CO-hydrogen-bonded (or protonated) [Pt(3)(mu-PBu(t)(2))(3)(H)(CO)(2)].HOTf (3). An ab initio theoretical study predicts a hydrogen-bonded complex or a proton-transfer tight ion pair as a possible candidate for the structure of the kinetic intermediate.     

An intramolecular N-H...(mu-H)Re2 dihydrogen bond and a novel mu 3-eta 2 coordination mode of the pyrazolate anion on a triangular cluster face

The quantitative addition of pyrazole (Hpz) to the 44 valence-electron, triangular cluster anion [Re3(mu 3-H)-(mu-H)3(CO)9]- gives the novel unsaturated anion [Re3(mu-H)4(CO)9(Hpz)]- (1, 46 valence electrons), which contains a pyrazole molecule that is terminally coordinated on a cluster vertex. Solidstate X-ray and IR analyses reveal a rather weak hydrogen-bonding interaction between the NH proton and one of the hydrides bridging the opposite triangular cluster edge (delta H degree = -3.1 kcal mol-1 from the Iogansen equation). Both IR and NMR data indicate that such a proton-hydride interaction is maintained in the major conformer present in CD2Cl2, but also provide evidence of the presence of minor conformers of 1 in which the NH proton is involved in an intermolecular hydrogen bond with the solvent. The mu-H...HN bond length evaluated in solution through the T1 minimum value (2.07 A) and that determined in the solid state by X-ray diffraction (2.05 A) are in good agreement. NMR experiments show that, in acetone, intermolecular N-H...solvent interactions replace the intramolecular dihydrogen bond. At room temperature in CH2Cl2, the pyrazole ligand in 1 is labile and 1 slowly "disproportionates" to [Re3(mu 3-H)-(mu-H)3(CO)9]- and [Re3(mu-H)3(CO)9-(mu-eta 2-pz)(Hpz)]-, with H2 evolution. Slow H2 evolution also leads to the formation of the anion [Re3(mu-H)3-(CO)9(pz)]- (5), in which the pyrazolate anion adopts a novel mu 3-eta 2-coordination mode, as revealed by a single-crystal X-ray analysis. The analysis of the bond lengths indicates that the pyrazolate anion in 5 acts as a six-electron donor, with loss of the aromaticity. The formation of 5 from 1 is much faster in solvents with a high dielectric constant, such as acetone or DMF. Anion 5 was also obtained from the reaction of pyrazole with [Re3(mu-H)3(CO)9(mu 3-CH3)]- through the intermediate formation of two isomeric addition derivatives and following CH4 evolution.     

Reactions of the dianion [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2- with transition-metal cations: facile insertion and then extrusion of cluster vertexes

The manganacarborane dianion in [N(PPh(3))(2)][NEt(4)][1,1,1-(CO)(3)-2-Ph-closo-1,2-MnCB(9)H(9)] (1b) reacts with cationic transition metal-ligand fragments to give products in which the electrophilic metal groups (M') are exo-polyhedrally attached to the {closo-1,2-MnCB(9)} cage system via three-center two-electron B-H --> M' linkages and generally also by Mn-M' bonds. With {Cu(PPh(3))}(+), the Cu-Mn-Cu trimetallic species [1,6-{Cu(PPh(3))}-1,7-{Cu(PPh(3))}-6,7-(mu-H)(2)-1,1,1-(CO)(3)-2-Ph-closo-1,2-MnCB(9)H(7)] (3a) is formed, whereas reactions with {M'(dppe)}(2+) (M' = Ni, Pd; dppe = Ph(2)PCH(2)CH(2)PPh(2)) give [1,3-{Ni(dppe)}-3-(mu-H)-1,1,1-(CO)(3)-2-Ph-closo-1,2-MnCB(9)H(8)] (5a) and [1,3,6-{Pd(dppe)}-3,6-(mu-H)(2)-1,1,1-(CO)(3)-2-Ph-closo-1,2-MnCB(9)H(7)] (5b), both of which contain M'-Mn bonds. The latter reaction with M' = Pt affords [3,6-{Pt(dppe)}-3,6-(mu-H)(2)-1,1,1-(CO)(3)-2-Ph-closo-1,2-MnCB(9)H(7)] (6), which lacks a Pt-Mn connectivity. Compound 6 itself spontaneously converts to [1-Ph-2,2,2-(CO)(3)-8,8-(dppe)-hypercloso-8,2,1-PtMnCB(9)H(9)] (7b) and thence to [3,6,7-{Mn(CO)(3)}-3,7-(mu-H)(2)-1-Ph-6,6-(dppe)-closo-6,1-PtCB(8)H(6)] (8). This sequence occurs via initial insertion of the {Pt(dppe)} unit and then extrusion of {Mn(CO)(3)} and one {BH} vertex. In the presence of alcohols ROH, compound 6 is transformed to the 7-OR substituted analogues of 7b. X-ray diffraction studies were essential in elucidating the structures encountered in compounds 5-8 and hence in understanding their behavior.     

Reaction properties of the trans-hyponitrite complex [Ru2(CO)4(mu-H)(mu-PBu(t)2)(mu-Ph2PCH2PPh2)(mu-eta2-ONNO)

The protonation of [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNO)] (1) with HBF(4) occurs at the oxygen of the noncoordinating side of the trans-hyponitrite ligand to give [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOH)][BF(4)] (2) in good yield. The monoprotonated hyponitrite in 2 is deprotonated easily by strong bases to regenerate 1. Furthermore, 1 reacts with the methylating reagent [Me(3)O][BF(4)] to afford [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOMe)][BF(4)] (3). The molecular structures of 2 and 3 have been determined crystallographically, and the structure of 2 is discussed with the results of the DFT/B3LYP calculations on the model complex [Ru(2)(CO)(4)(mu-H)(mu-PH(2))(mu-H(2)PCH(2)PH(2))(mu-eta(2)-ONNOH)](+) (2a). Moreover, the thermolysis of 2 in ethanol affords [Ru(2)(CO)(4)(mu-H)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)][BF(4)] (4) in high yield, and the deprotonation of 4 by DBU in THF yields the novel complex [Ru(2)(CO)(4)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)] (5).     

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.     

Dinuclear ruthenium and iron complexes containing palladium and platinum with tri-tert-butylphosphine ligands: synthesis, structures, and bonding

The reaction of Pd(PBu(t)(3))(2) with Ru(CO)(5) yielded the dipalladium-diruthenium cluster complex Ru(2)(CO)(9)[Pd(PBu(t)(3))](2), 10. The reaction of Pt(PBu(t)(3))(2) with Ru(CO)(5) at room temperature afforded the diplatinum-diruthenium cluster complex Ru(2)(CO)(9)[Pt(PBu(t)(3))](2), 12, and the monoplatinum-diruthenium cluster PtRu(2)(CO)(9)(PBu(t)(3)), 11. All three complexes contain a diruthenium group with bridging Pd(PBu(t)(3)) or Pt(PBu(t)(3)) groups. Compound 11 can be converted to 12 by reaction with an additional quantity of Pt(PBu(t)(3))(2). The reaction of 12 with hydrogen at 68 degrees C yielded the dihydrido complex Pt(2)Ru(2)(CO)(8)(PBu(t)(3))(2)(micro-H)(2), 13. This complex contains a Ru(2)Pt(2) cluster with hydride ligands bridging two of the Ru-Pt bonds. The reaction of Fe(2)(CO)(9) with Pt(PBu(t)(3))(2) yielded the platinum-diiron cluster complex PtFe(2)(CO)(9)(PBu(t)(3)), 14, which is analogous to 11. All new complexes were characterized crystallographically. Molecular orbital calculations of 10 reveal an unusual delocalized metal-metal bonding system involving the Pd(PBu(t)(3)) groups and the Ru(2)(CO)(9) group.     

Platinum-osmium cluster complexes from the addition of Pt(PBut3) groups to Os3(CO)12

Three new compounds, PtOs(3)(CO)(12)(PBu(t)(3)) (10), Pt(2)Os(3)(CO)(12)(PBu(t)(3))(2) (11), and Pt(3)Os(3)(CO)(12)(PBu(t)(3))(3) (12), have been obtained from the reaction of Pt(PBu(t)(3))(2) with Os(3)(CO)(12) (9). The products were formed by the sequential addition of 1-3 Pt(PBu(t)(3)) groups to the three Os-Os bonds of the metal cluster of Os(3)(CO)(12). In solution, compounds 10-12 interconvert among themselves by intermolecular exchange of the Pt(PBu(t)(3)) groups. When 11 is treated with PPh(3), the mono- and bis(PPh(3)) derivatives of 9, Os(3)(CO)(11)(PPh(3)) and Os(3)(CO)(10)(PPh(3))(2), were obtained by elimination of the Pt(PBu(t)(3)) groups together with one and two CO ligands, respectively. When heated, compound 11 was transformed into the new compound Pt(2)Os(3)(CO)(10)(PBu(t)(3))(PBu(t)(2)CMe(2)CH(2))(mu-H) (13) by the loss of two CO ligands and a metalation of one of the methyl groups of one of the PBu(t)(3) ligands. Compounds 10-13 have been characterized by single-crystal X-ray diffraction analyses.     

Synthesis of PtRu5(CO)14(PBu(t)3)(mu-H)2(mu6-C) and its reactions with Pt(PBut3)2, HGePh3, and HSnPh3

Reaction of PtRu5(CO)15(PBut3)(C), 3, with hydrogen at 97 degrees C yielded the new dihydride-containing cluster compound PtRu5(CO)14(PBut3)(mu-H)2(mu6-C), 5. Compound 5 was characterized crystallographically and was shown to contain an octahedral cluster consisting of one platinum and five ruthenium atoms with a carbido ligand in the center. Two hydrido ligands bridge two oppositely positioned PtRu bonds. Compound 5 reacts with Pt(PBut3)2 to yield Pt2Ru5(CO)14(PBut3)2(mu-H)2(mu6-C), 6, a Pt(PBut3) adduct of 5, by adding a Pt(PBut3) group as a bridge across one of the Ru-Ru bonds in the square base of the Ru5 portion of the cluster. Compound 6 is dynamically active on the NMR time scale by a mechanism that appears to involve a shifting of the Pt(PBut3) group from one Ru-Ru bond to another. Two new complexes, PtRu5(CO)13(PBut3)(mu-H)3(GePh3)(mu5-C), 7, and PtRu5(CO)13(PBut3)(mu-H)2(mu-GePh2)(mu6-C), 8, were obtained from the reaction of 5 with HGePh3. The cluster of 7 has an open structure in which the Pt(PBut3) group bridges an edge of the square base of the square pyramidal Ru5 cluster. Compound 7 also has three bridging hydrido ligands and one terminal GePh3 ligand. When heated to 97 degrees C, 7 is slowly converted to 8 by cleavage of a phenyl group from the GePh3 ligand and elimination of benzene by its combination with one of the hydrido ligands. The PtRu5 metal cluster of 8 has a closed octahedral shape with a GePh2 ligand bridging one of the Ru-Ru bonds. Two tin-containing compounds, PtRu5(CO)13(PBut3)(mu-H)3(SnPh3)(mu5-C), 9, and PtRu5(CO)13(PBut3)(mu-H)2(mu-SnPh2)(mu6-C), 10, which are analogous to 7 and 8 were obtained from the reaction of 5 with HSnPh3.     

Substitution, cage functionalization, and oxidation of the charge-compensated triruthenium monocarbollide cluster complex [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)6}-closo-2,1-RuCB10H8

The compound [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)6}-closo-2,1-RuCB10H8] 1a reacts with PMe3 or PCy3(Cy = cyclo-C6H11) to give the structurally different species [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)5(PMe3)}-closo-2,1-RuCB10H8] 4 and [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(CO)5(PCy3)}-closo-2,1-RuCB10H8]5, respectively. A symmetrically disubstituted product [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)4(PMe3)2}-closo-2,1-RuCB10H8] 6 is obtained using an excess of PMe3. In contrast, the chelating diphosphines 1,1'-(PPh2)2-Fe(eta-C5H4)2 and 1,2-(PPh2)2-closo-1,2-C2B10H10 react with 1a to yield oxidative-insertion species [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(micro-[1',1'-(PPh2)2-Fe(eta-C5H4)2])(CO)4}-closo-2,1-RuCB10H8] 7 and [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(CO)4(1',2'-(PPh2)2-closo-1',2'-C2B10H10)}-closo-2,1-RuCB10H8] 8, respectively. In toluene at reflux temperatures, 1a with Bu(t)SSBu(t) gives [1-SMe2-2,2-(CO)2-7-(mu-SBu(t))-11-(mu-H)-2,7,11-{Ru2(mu-H)(mu-SBu(t))(CO)4}-closo-2,1-RuCB10H8] 9, and with Bu(t)C [triple bond] CH gives [1-SMe2-2,2-(CO)2-7-{mu:eta2-(E)-CH=C(H)Bu(t)}-11-{mu:eta2-(E)-CH=C(H)Bu(t)}-2,7,11-{Ru2(CO)5}-closo-2,1-RuCB10H8] 10. In the latter, two alkyne groups have inserted into cage B-H groups, with one of the resulting B-vinyl moieties involved in a C-H...Ru agostic bond. Oxidation of 1a with I2 or HgCl2 affords the mononuclear ruthenium complex [1-SMe2-2,2,2-(CO)3-closo-2,1-RuCB10H10] 11.     

Bimetallic cluster complexes: the synthesis, structures, and bonding of ruthenium carbonyl cluster complexes containing palladium and platinum with the bulky tri-tert-butyl-phosphine ligand

The bis-phosphine compounds M(PBut3)2, M = Pd and Pt, readily eliminate one PBut3 ligand and transfer MPBut3 groups to the ruthenium-ruthenium bonds in the compounds Ru3(CO)12, Ru6(CO)17(micro6-C), and Ru6(CO)14(eta6-C6H6)(micro6-C) without displacement of any of the ligands on the ruthenium complexes. The new compounds, Ru3(CO)12[Pd(PBut3)]3, 10, and Ru6(CO)17(micro6-C)[Pd(PBut3)]2, 11, Ru6(CO)17(micro6-C)[Pt(PBut3)]n, n = 1 (12), n = 2 (13), and Ru6(CO)14(eta6-C6H6)(micro6-C)[Pd(PBut3)]n, n = 1 (15), n = 2 (16), have been prepared and structurally characterized. In most cases the MPBut3 groups bridge a pair of mutually bonded ruthenium atoms, and the associated Ru-Ru bond distance increases in length. Fenske-Hall calculations were performed on 10 and 11 to develop an understanding of the electron deficient metal-metal bonding. 10 undergoes a Jahn-Teller distortion to increase bonding interactions between neighboring Ru(CO)4 and Pd(PBut3) fragments. 11 has seven molecular orbitals important to cluster bonding in accord with cluster electron-counting rules.     

Platinum-rhodium carbonyl clusters: new structures and new types of dynamical activity

The reaction of Rh(4)(CO)(12) with Pt(PBu(t)(3))(2) in CH(2)Cl(2) at room temperature yielded three new complexes: Rh(4)(CO)(4)-(mu-CO)(4)(mu(4)-CO)(PBu(t)(3))(2)[Pt(PBu(t)(3))], 10, Rh(2)(CO)(8)[Pt(PBu(t)(3))](2)[Pt(CO)], 11, and Rh(2)(CO)(8)[Pt(PBu(t)(3))](3), 12. The reaction of Rh(4)(CO)(12) with an excess of Pt(PBu(t)(3))(2) in hexane at 68 degrees C yielded the new hexarhodium-tetraplatinum compound, Rh(6)(CO)(16)[Pt(PBu(t)(3))](4), 13, in a low yield. All four compounds were characterized by (31)P NMR and single-crystal X-ray diffraction analyses. Compound 10 contains an unsymmetrical quadruply bridging carbonyl ligand in the fold of a butterfly tetrahedral cluster of four rhodium atoms with a Pt(PBu(t)(3)) group bridging the hinge of the butterfly tetrahedron. Compound 11 contains an unsaturated trigonal bipyramidal Rh(2)Pt(3) cluster. Compound 12 is similar to 11 except the trigonal bipyramidal Rh(2)Pt(3) cluster opened by cleavage of one Pt-Rh bond due to steric interactions produced by the replacement of one of the carbonyl ligands in 11 with a tri-tert-butylphosphine ligand. Compound 12 undergoes facile dynamical rearrangements of the metal atoms in the cluster which average the three inequivalent phosphine ligands on the platinum atoms. Compound 13 contains an octahedral cluster of six rhodium atoms with four Pt(PBu(t)(3)) groups bridging edges of that octahedron.     

Synthesis and structural characterization of configurational isomers of tungsten-palladium complexes with bridging diphenyl(dithioalkoxycarbonyl)phosphine as a ligand and phosphine transfer from tungsten to palladium

Treatment of the complex [W(CO)5[PPh2(CS2Me)]] (2) with [Pd(PPh3)4] (1) affords binuclear complexes such as anti-[(Ph3P)2Pd[mu-eta 1,eta 2-(CS2Me)PPh2]W(CO)5] (3), syn-[(Ph3P)2Pd[mu-eta 1,eta 2-(CS2Me)PPh2]W(CO)5] (4), and trans-[W(CO)4(PPh3)2] (5). In 3 and 4, respectively, the W and Pd atoms are in anti and syn configurations with respect to the P-CS2 bond of the diphenyl(dithiomethoxycarbonyl)phosphine ligand, PPh2(CS2Me). Complex 3 undergoes extensive rearrangement in CHCl3 at room temperature by transfer of a PPh3 ligand from Pd to W, eliminating [W(CO)5(PPh3)] (7), while the PPh2CS2Me ligand transfers from W to Pd to give [[(Ph3P)Pd[mu-eta 1,eta 2-(CS2Me)PPh2]]2] (6). In complex 6, the [Pd(PPh3)] fragments are held together by two bridging PPh2(CS2Me) ligands. Each PPh2(CS2Me) ligand is pi-bonded to one Pd atom through the C=S linkage and sigma-bonded to the other Pd through the phosphorus atom, resulting in a six-membered ring. Treatment of Pd(PPh3)4 with [W(CO)5[PPh2[CS2(CH2)nCN]]] (n = 1, 8a; n = 2, 8b) in CH2Cl2 affords syn-[(Ph3P)2Pd[mu-eta 1,eta 2-[CS2(CH2)nCN]PPh2]W(CO)5] (n = 1, 9a; n = 2, 9b). Similar configurational products syn-[(Ph3P)2Pd[mu-eta 1,eta 2-(CS2R)PPh2]W(CO)5] (R = C2H5, C3H5, C2H4OH, C3H6CN, 11a-d) are synthesized by the reaction of Pd(PPh3)4 with [W(CO)5[PPh2(CS2R)]] (R = C2H5, C3H5, C2H4OH, C3H6CN, 10a-d). Although complexes 11a-d have the same configuration as 9a,b, the SR group is oriented away from Pd in the former and near Pd in the latter. In these complexes, the diphenyl(dithioalkoxycarbonyl)phosphine ligand is bound to the two metals through the C=S pi-bonding and to phosphorus through the sigma-bonding. All of the complexes are identified by spectroscopic methods, and the structures of complexes 3, 6, 9a, and 11d are determined by single-crystal X-ray diffraction. Complexes 3, 9, and 11d crystallize in the triclinic space group P1 with Z = 2, whereas 6 belongs to the monoclinic space group P2/c with Z = 4. The cell dimensions are as follows: for 3, a = 10.920(3) A, b = 14.707(5) A, c = 16.654(5) A, alpha = 99.98(3) degrees, beta = 93.75(3) degrees, gamma = 99.44(3) degrees; for 6, a = 15.106(3) A, b = 9.848(3) A, c = 20.528(4) A, beta = 104.85(2) degrees; for 9a, a = 11.125(3) A, b = 14.089(4) A, c = 17.947(7) A, alpha = 80.13(3) degrees, beta = 80.39(3) degrees, gamma = 89.76(2) degrees; for 11d, a = 11.692(3) A, b = 13.602(9) A, c = 18.471(10) A, alpha = 81.29(5) degrees, beta = 80.88(3) degrees, gamma = 88.82(1) degrees.     

High-nuclearity iridium carbonyl clusters containing phenylgermyl ligands: synthesis, structures, and reactivity

The reaction of Ir4(CO)12 with Ph3GeH at 97 degrees C has yielded the new tetrairidium cluster complexes Ir4(CO)7(GePh3)(mu-GePh2)2[mu3-eta3-GePh(C6H4)](mu-H)2 (10) and Ir4(CO)8(GePh3)2(mu-GePh2)4 (11). The structure of 10 consists of a tetrahedral Ir4 cluster with seven terminal CO groups, two bridging GePh2) ligands, an ortho-metallated bridging mu3-eta3-GePh(C6H4) group, a terminal GePh3 ligand, and two bridging hydrido ligands. Compound 11 consists of a planar butterfly arrangement of four iridium atoms with four bridging GePh2 and two terminal GePh3 ligands. The same reaction at 125 degrees C yielded the two new triiridium clusters Ir3(CO)5(GePh3)(mu-GePh2)3(mu3-GePh)(mu-H) (12) and Ir3(CO)6(GePh3)3(mu-GePh2)3 (13). Compound 12 contains a triangular Ir3 cluster with three bridging GePh2), one triply bridging GePh, and one terminal GePh3 ligand. The compound also contains a hydrido ligand that bridges one of the Ir-Ge bonds. Compound 13 contains a triangular Ir3 cluster with three bridging GePh2 and three terminal GePh3 ligands. At 151 degrees C, an additional complex, Ir4H4(CO)4(mu-GePh2)4(mu4-GePh)2 (14), was isolated. Compound 14 consists of an Ir4 square with four bridging GePh2, two quadruply bridging GePh groups, and four terminal hydrido ligands. Compound 12 reacts with CO at 125 degrees C to give the compound Ir3(CO)6(mu-GePh2)3(mu3-GePh) (15). Compound 15 is formed via the loss of the hydrido ligand and the terminal GePh3 ligand and the addition of one carbonyl ligand to 12. All compounds were fully characterized by IR, NMR, single-crystal X-ray diffraction analysis, and elemental analysis.     

Pt(0) and Pd(0) olefin complexes of the metalloid N-heterocyclic carbene analogues [E(I)(ddp)] (ddp=2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}-2-pentene; E=Al, Ga): ligand substitution, H--H and Si--H bond activation, and cluster formation

Various products of the reaction of [E(ddp)] (ddp=2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}-2-pentene; E=Al, Ga) with Pt(0) and Pd(0) olefin complexes are reported. Thus, the reaction of [Pt(cod)(2)] (cod=1,5-cyclooctadiene) with two equivalents of [Ga(ddp)] yields [Pt(1,3-cod){Ga(ddp)}(2)] (1), whereas treatment of [Pd(2)(dvds)(3)] (dvds=1,1,3,3-tetramethyl1,3-divinyldisiloxane) with [E(ddp)] leads to the monomeric compounds [(dvds)Pd{E(ddp)}] (E=Ga (2 a), Al (2 b)) by substitution of the bridging dvds ligand. Both 1 and 2 a readily react with strong pi-acceptor ligands such as CO or tBuNC to give the dimeric compounds [M{mu(2)-Ga(ddp)}(L)] (L=CO, tBuNC; M=Pt (3 a, 5 a), Pd (3 b, 5 b)), respectively. Based on (1)H NMR spectroscopic data, [Pt{Ga(ddp)}(2)(CO)] is likely to be an intermediate in the formation of 3 a. Furthermore, reactions of 1 with H(2) and HSiEt(3) yield the monomeric compounds [Pt{Ga(ddp)}(2)(H)(2)] (7) and [Pt{Ga(ddp)}(2)(H)(SiEt(3))] (8). Finally, the reaction of [Pt(cod)(2)] with one equivalent of [Ga(ddp)] in the presence of H(2) in hexane gives the new dimeric cluster [Pt{mu(2)-Ga(ddp)}(H)(2)](2) (9).     

Reactivity of molybdenum and rhenium hydroxo-carbonyl complexes toward organic electrophiles

The hydroxo compounds [Re(OH)(CO)(3)(N-N)] (N-N=bipy, 2 a; Me(2)-bipy, 2 b) were prepared in a biphasic H(2)O/CH(2)Cl(2) medium by reaction of [Re(OTf)(CO)(3)(N-N)] with KOH. In contrast, when anhydrous CH(2)Cl(2) was used, the binuclear hydroxo-bridged compound [[Re(CO)(3)(bipy)](2)(mu-OH)]OTf (3-OTf) was obtained. Compound [Re(OH)(CO)(3)(Me(2)-bipy)] (2 b) reacted with phenyl acetate or vinyl acetate to afford [Re(OAc)(CO)(3)(Me(2)-bipy)] (4) and phenol or acetaldehyde, respectively. The reactions of [Mo(OH)(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (1), 2 a, and 2 b toward several unsaturated organic electrophiles were studied. The reaction of 1 with (p-tolyl)isocyanate afforded an adduct of N,N'-di(p-tolyl)urea and the carbonato-bridged compound [[Mo(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)](2)(mu-eta(1)(O),eta(1)(O)-CO(3))] (5). In contrast, the reaction of 2 a with phenylisocyanate afforded [Re(OC(O)NHPh)(CO)(3)(bipy)] (6); this results from formal PhNCO insertion into the O-H bond. On the other hand, compounds [Mo[SC(O)NH(p-tolyl)](eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (7), [Re[SC(O)NH(p-tolyl)](CO)(3)(Me(2)-bipy)] (8 a), and [Re[SC(O)NHEt](CO)(3)(Me(2)-bipy)] (8 b) were obtained by reaction of 1 or 2 b with the corresponding alkyl or aryl isothiocyanates. In those cases, RNCS was inserted into the M-O bond. The reactions of 1, 2 a, and 2 b with dimethylacetylenedicarboxylate (DMAD) gave the complexes [Mo[C(OH)-C(CO(2)Me)C(CO(2)Me)-O](eta(3)-C(3)H(4)-Me-2)(CO)(phen)] (9) and [Re[C(OH)C(CO(2)Me)C(CO(2)Me)O](CO)(2)(N-N)] (N-N=bipy, 10 a; Me(2)-bipy, 10 b). The molecules of these compounds contain five-membered metallacycles that are the result of coupling between the hydroxo ligand, DMAD, and one of the CO ligands. The new compounds were characterized by a combination of IR and NMR spectroscopy, and for [[Re(CO)(3)(bipy)(2)(mu-OH)]BF(4) (3-BF(4)), 4, 5, 6, 7, 8 b, 9, and 10 b, also by means of single-crystal X-ray diffraction.