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Vicki H. Grassian, Gerald Meyer, Hector Abruna, Geoffrey W. Coates, Luke Ekem Achenie, TomAllison, Bruce Brunschwig, John Ferry, Miguel Garcia-Garibay, Jorge Gardea-Torresdey, Clare P.Grey, James Hutchison, Chao-Jun Li, Charles Liotta, Arthur Raguskas, Shelley Minteer, Karl Mueller,Jeffrey Roberts, Omowunmi Sadik, Russell Schmehl, William Schneider, Annabella Selloni, Peter Stair,Jon Stewart, David Thorn, Julian Tyson, Bettina Voelker, J. Michael White, and Frankie Wood-Black

Electrospray mass spectrometry (ESMS) is used to investigate cationic niobium and tantalum alkoxide clusters generated in solution by adding equal molar amounts of B(C6F5)3 to the metal ethoxide, M(OEt)5. The dominant metal ethoxide cations that were observed in the electrospray mass spectrum correspond to M(OEt)4+, M2O(OEt)7+, M2(OEt)9+, and M3O(OEt)12+, where M is niobium or tantalum. In separate experiments heterometallic Nb/Ta ethoxide clusters were produced, and the heterometallic cations present in the electrospray mass spectrum are NbTaO(OEt)7+, NbTa(OEt)9+, Nb2TaO(OEt)12+, and NbTa2O(OEt)12+. Collision-induced dissociation (CID) experiments were completed to provide structural information about the observed metal ethoxide cations. At low collision energy (ECM < 2 eV), the CID fragmentation pattern of Nb3O(OEt)12+ favors loss of Nb2(OEt)9+ and neutral NbO(OEt)3, whereas the fragmentation pattern of Ta3O(OEt)12+ favors loss of Ta2O(OEt)7+ and neutral Ta(OEt)5. In addition, the major CID product of M...

Photolysis of [(CpMo(CO)3]2 with InR3 (R = ethyl, t-butyl, neopentyl) or ZnR2 (R = ethyl) efficiently forms CpMo(CO)3InR2 or [(CpMo(CO)3]2Zn as major products. The reaction is believed to proceed by bimolecular radical substitution and demonstrates substantial strenght for the MoIn bond. As a consequence of this bond strenght, [CpMo(CO)3]2 reacts photochemically and reversibly with indium metal to form [CpMo(CO)3]3In.

A general synthesis for the preparation of alkyl N,N'-beta-diketimines has been developed. The method reported here demonstrates the use of dimethyl sulfate for conversion of enaminoketones to beta-diketimines. The reaction can be performed without solvent, providing good yields.

C(60) and liquid bromine react to form C(60)Br(24), a crystalline compound isolated as a bromine solvate, C(60)Br(24)(Br(2))(x), The x-ray crystal structure defines a new pattern of addition to the carbon skeleton that imparts a rare high symmetry. The parent C(60) framework is recognizable in C(60)Br(24), but sp(3) carbons at sites of bromination distort the surface, affecting conformations of all of the hexagonal and pentagonal rings. Twenty-four bromine atoms envelop the carbon core, shielding the 18 remaining double bonds from addition. At 150 degrees to 200 degrees C there is effectively quantitative reversion of C(60)Br(24) to C(60) and Br(2).

cis-(Dimethyl)(tri-p-tolylphosphine)(ligand)platinum(II) complexes (ligand  substituted pyridine or amine) have been prepared from PtMe2(1,5-COD) (COD  cyclooctadiene), Ptol3 (tol  tolyl) and the N-donor ligand. For ligand  4-(5-phenyl-2-oxazolyl)pyridine the crystal and molecular structure has been determined: space group R3−, a  b  34.295(5), c  14.198(2) A (− 100°C), γ 120°, V 14459 A3, Z  18. For 379 variables and 4977 reflections with I > 2σ(I) R  0.034, Rw  0.042. PtC bond lengths are 2.082(7) (rans to P) and 2.059(8) A (trans to N). Amine ligands are displaced by ethylene to form an unstable ethylene adduct.

When bound in transition metal complexes, organic molecules such as olefins, acetylenes, polyenes, cyclopolyenes and carbenes exhibit a variety of equilibrium geometries. The range of observed barriers to a conformational change as simple as rotation around the metal-ligand coordination axis is impressively large, from 0 to > 40 kcal/mole. Clearly it is electronic factors that are operative in setting the preferred geometries in these molecules and in controlling the magnitude of the conformational barriers. In this lecture several specific examples of the theory of these conformational phenomena will be presented.

The reduction of RhCl 3 - 3 H 2 O by sodium amalgam in THF solution under an atmosphere of N 2 and in the presence of an excess of a phosphine ligand has resulted in the formation of the hydridodinitrogen complexes RhH(N 2 )-(PPh(t-Bu) 2 ) 2 (I), RhH(N 2 )(P(t-Bu) 3 ) 2 (II), and [RhH(P(cyclo-C 6 H 11 ) 3 ) 2 ] 2 (μ-N 2 )(V), and a hydridotrisphosphine complex RhH(P(i-Pr) 3 ) 3 (X). The dinitrogen coordination is stable in I but N 2 is readily lost from other dinitrogen complexes, permitting the isolation of three-coordinate hydridobisphosphine rhodium(I) complexes RhH(P(t-Bu) 3 ) 2 (VII) and RhH(P(cyclo-C 6 H 11 ) 3 ) 2 (VIII). Trihydrido complexes RhH 3 L 2 (L = PPh(t-Bu) 2 (XI), P(t-Bu) 3 (XII), P(cyclo-C 6 H 11 ) 2 (XIII), and P(i-Pr) 3 (XIV)) have been synthesized by the reaction of the above rhodium (I) compounds with H 2 . By treatment of the corresponding trihydrido complexes with N 2 we have been able to obtain RhH(N 2 )-(P(cyclo-C 6 H 11 ) 3 ) 2 (III) and RhH(N 2 )(P(i-Pr) 3 ) 2 (IV). Loss of N 2 from IV results in the formation of [RhH(P(i-Pr) 3 ) 2 ] 2 (μ-N 2 ) (VI) and RhH(P(i-Pr) 3 ) 2 (IX). The crystal and molecular structure of [RhH(P(i-Pr) 3 ) 2 ] 2 (μ-N 2 ) (VI) has been determined at —85°C. The compound crystallizes in the triclinic space group C P 1 with two molecules in a cell dimensions a 12.703(16), b 16.455(16), c 11.389(8) A, α 90.25(9), β 103.87(3), γ 97.58(3)°, V 2289 A 3 . The final conventional and weighted agreement indices on F o for F o 2 τ3σ( F o 2 ) are 0.051 and 0.060, respectively. The dinitrogen ligand of VI linearly bridges two planar RhHP 2 fragments with NN separation of 1.134(5) A and an average RhN bond distance of 1.977(6) A. The dihedral angle between the two RhHP 2 fragments is 55.2°. Overall, the dimeric complex effectively has D 2 (222) symmetry.