Ion pairs from redox reaction of decamethylchromocene with cyclopentadienyltitanium trichlorides

Decamethylchromocene [Cr(eta(5)-C5Me5)(2)] reacted with cyclopentadienyltitanium trichlorides [Ti(eta(5)-C5H5-nMen)Cl-3] (n = 0-5) in toluene to precipitate yellow finely crystalline ion pairs [Cr(eta(5)-C5Me5)(2)]Ti+(eta(5)-C5H(5-n)Me(n))Cl-3](-) (1-6). Evidence for the chromocenium cation and titanate anions was obtained by paramagnetic H-1 NMR spectra of 1-6 in CD2Cl2. The resonance of the cation was invariant at delta 6.9 ppm (Delta v(1/2) similar to 0.4 kHz) whereas resonances of the titanate anions were shifting in response to the number of methyl groups (delta 10.5-8.4 ppm (CpMe) and delta 26.6-39.0 ppm (CpH)). The presence of toluene of crystallization in 1-6 was observed by H-1 NMR spectra, and in the crystal structure of 6. Crystallization of 6 from tetrahydrofuran afforded solvent-free crystals of 6A. In crystal structures of both 6 and 6A the [Ti(eta(5)-C5Me5)Cl-3](-) titanate anion possessed shorter Ti-Cg distances and longer Tr-Cl bonds than the neutral species. (C) 2012 Elsevier B.V. All rights reserved.