Preparation of Monocarbon Polymetallocarboranes and the Crystal and Molecular Structure of a Novel Electron-Rich Nido-Trimetallocarborane,
CALIFORNIA UNIV LOS ANGELES DEPT OF CHEMISTRY
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Reaction of nido-3-R-2-CB5H8 RH or CH3 with nickelocene and sodium amalgam has yielded the first trimetallocarboranes containing nickel, C5H5Ni3CB5H5R, isolated in several isomeric forms. The complexes are formulated as formal mixed-valence NiIII-NiIII-NiIV systems the near infrared spectra support this formulation and indicate substantial mixed-valence charge transfer. Reaction of closo-1-CB9H10- with cobaltocene and sodium amalgam produced the closo-icosahedral bimetallic species C5H5Co2CB9H10- containing a metal-metal bond. The crystal structure of one isomer of C5H5Ni3CB5H6 was determined from three-dimensional X-ray counter data. The complex crystallizes in the orthorhombic system, space group Pbnm alternate setting of Pnma with a7.5181 A, b 14.7402 A, c 15.7113 A and Z 4. The electron-rich trimetallocarborane was found to adopt a novel nido geometry best described as a distorted monocapped square antiprism. Three nickel atoms and a boron atom compose the four-membered open face the two equivalent nickel-nickel distances are 2.4041 A. Non-bonded distances in the open face are Ni-Ni 3.2501 A and Ni-B - 2.9915 A. The geometry is discussed in relation to electron counting rules for polyhedral heteroboranes.
- Organic Chemistry
- Atomic and Molecular Physics and Spectroscopy