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Metal-metal multiple bonds. 10. Electrophilic additions of halogens and hydrogen halides to the Mo-Mo triple bond in Cp/sub 2/Mo/sub 2/(CO)/sub 4/

Journal Article · · J. Am. Chem. Soc.; (United States)
DOI:https://doi.org/10.1021/ja00347a028· OSTI ID:5719382
The synthesis of Cp/sub 2/Mo/sub 2/(CO)/sub 4/(..mu..-Cl)(Cl) (6), Cp/sub 2/Mo/sub 2/(CO)/sub 4/(..mu..-H)(..mu..-I) (8), and Cp/sub 2/Mo/sub 2/(CO)/sub 4/(..mu..-I)/sub 2/ (2) is described. Complex 6 is best prepared from Cp/sub 2/Mo/sub 2/(CO)/sub 4/ (1) and PhICl/sub 2/ or HCl in toluene. Complex 8 is formed from 1 and HI. Excess HI converts 8 to the diiodide 2. Reaction of 2 with aluminum hydrides gives 8, which in turn reacts to give H/sub 2/ and 1. The XPS of 6 shows two types of chlorine in a 1:1 ratio with 2P/sub 3///sub 2/ ionization energies of 198.8 and 197.6 eV consistent with bridging and terminal positions, respectively. The different geometrical isomers that are exhibited by the dihalides are discussed. The structures of 2 and 8 were determined by X-ray crystallography. For 2, the violet isomer forms crystals in the triclinic system, a, b, c = 6.882 (1), 10.196 (2), 6.856 (1) angstrom; ..cap alpha.., ..beta.., ..gamma.. = 86.08 (1), 113.83 (1), 102.52 (1)/sup 0/, V = 429.5 (1) angstrom/sup 3/, Z = 1, space group P1, rho(calcd) = 2.62 g/cm/sup 3/. The structure was refined with 1702 reflections with I > 3sigma(I) to final R values of R/sub 1/ = 0.063 and R/sub 2/ = 0.073. The bridging hydrogen was not located. Selected interatomic distances (angstrom) and bond angles follow: Mo-Mo = 3.310 (2), Mo-I = 2.760 (1); MoIMo = 73.70 (4), IMoMo = 53.15 (av). The nature of the bridging Mo(..mu..-H)(..mu..-X)Mo system is discussed in an EHMO framework, and the significant tilt of the Cp groups is ascribed to a trans influence propagated in the sigma(Mo-CO) and ..pi..(Mo-Cp) bonding orbitals.
Research Organization:
The Univ. of Michigan, Ann Arbor
OSTI ID:
5719382
Journal Information:
J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:9; ISSN JACSA
Country of Publication:
United States
Language:
English