Synthesis, structure, spectroscopic and electrochemical study of the paramagnetic compound [2-(eta(7)-C7H7)-7,11-F-2-2,1-closo-MoTeB10H8]

The reaction of [NEt4][7-nido-TeB10H11] 1 with [Mo(CO)(3)(eta (7)-C7H7)][BF 4] 2 in dichloromethane yields the novel paramagnetic, B-fluorinated, "mixe d-sandwich" compound [2-(eta (7)-C7H7)-7,11-F-2-2,1-closo-MoTeB10H8] 3 in 1 9% yield. An X-ray diffraction study of 3 establishes the closo twelve-vert ex MoTeB10-cage structure with two B-F units at adjacent positions. The str ucture of 3 was solved in space group Pna2(1) with unit cell dimensions of a=16.7598(18), b=12.5500(11), c=7.2607(18) Angstrom, and Z=4. The final R f actor was 0.0291 for 1471 observed reflections. Principal interatomic dista nces are Mo-Te 2.7083(8), B-F 1.396(9) and 1.410(9) Angstrom. In the MoTeB1 0 cage interatomic distances are in the ranges; Mo-B 2.363(8) to 2.481(9), Te-B 2.293(9) to 2.373(9) and B-B 1.720(13) to 1.943(12) Angstrom. EPR spec tra confirm the paramagnetic nature of 3 with the unpaired electron located in a mainly molybdenum-based molecular orbital. The cyclic voltammetric re sponse of 3 exhibits a reversible one-electron reduction at E-0'=-0.39 V in dichloromethane solvent.