Electron and Bromine Transfer Reactions between Metal Carbonyl Anions and Metal Carbonyl Bromides. Crystal and Molecular Structure of Dimeric Indenyl Molybdenum Tricarbonyl

Reactions of metal carbonyl anions with metal carbonyl halides proceed by two separate paths. When the reactant anion is a strong nucleophile, the halogen is transferred, resulting in a new metal carbonyl halide and a new metal carbonyl anion as intermediates. The ultimate products, in this case, are the homobimetallic complexes. In cases where the reactant metal carbonyl anion is a poor nucleophile, a single electron transfer occurs, leading to the two homobimetallic complexes and to the heterobimetallic complex. Halide effects and possible indenyl effects are examined. The complex [Mo(indenyl)(CO)₃]₂ crystallizes in the noncentrosymmetric orthorhombic space group P2₁2₁2₁ (No. 19) with a = 7.3572(7) Å, b = 14.4539(12) Å, c = 19.983(2) Å, V = 2125.0(4) ų, and Z = 4. Diffraction data were collected on a Siemens R3m/V diffractometer for 2θ = 5–45° (Mo Kα), and the structure was solved and refined to R = 3.21% and R_w = 3.23% for all 2786 independent reflections (R = 2.26% and R_w = 2.81% for those 2314 reflections with |F_o| > 6σ-(|F_o|). The complex is held together by a Mo-Mo single bond (Mo(l)-Mo(2) = 3.251(1) Å), and has Mo-CO distances ranging from 1.956(6) to 1.988(7) Å, averaging 1.970 ± 0.016 Å. Molybdenum-carbon distances to the η⁵-indenyl rings range from 2.300(7) to 2.427(6) Å for Mo(l) and 2.306(7) to 2.430(6) Å for Mo(2).