Synthesis and structure of nitrile-solvated rare earth metallocene cations [Cp2Ln(NCR)3][BPh4] (Cp = C5Me5, C5H4SiMe3; R = Me, tBu, Ph)

The coordination chemistry of MeCN, (BuCN)-Bu-t, and PhCN with the cationic rare earth metallocene complexes [(C5Me5)(2)Ln][(mu-Ph)(2)BPh2], 1-Ln (Ln = Y, La, Gd), has been examined to determine how nitrile coordination will affect the metallocene geometry. Crystallographic determination of geometry was possible for [((C5Me5)(2)Ln(NCMe)(3)][BPh4] (2-Y, 2-Gd), [(C5Me5)(2)Y((NCBu)-Bu-t)(3)][BPh4] (3-Y), and [(C5Me5)(2)Ln (NCPh)(3)][BPh4] (4-La, 4-Gd). In each case, only three nitriles are found to coordinate and the metallocenes are bent with (C5Me5 ring centroid)-metal-(C5Me5 ring centroid) angles of 137-140 degrees. The THF adduct, [(C5Me5)(2)La(NCMe)(2)(THF)][BPh4], 5-La, was also crystallographically characterized. A similar result was observed with the yttrium metallocene of the trimethylsilyl-containing ligand (C5H4SiMe3)(1-): coordination of only three nitriles is found in [(C5H4SiMe3)(2)Y(NCMe)(3)][BPh4], 6-Y, which has a 136.8 degrees (C5Me5 ring centroid)-Y-(C5Me5 ring centroid) angle. (C) 2015 Elsevier Ltd. All rights reserved.