[(η6-C6H6)RuII(L)(Cl/N3/CN/CH3CN)]+/2+ complexes of non-planar pyrazolylmethylpyridine ligands: Formation of helices due to C-H•••X (X = Cl, N) interaction

Structural analysis of a previously reported half-sandwich complex having three-legged piano-stool geometry [(eta(6)-C6H6)Ru-II(L-1)Cl][PF6] (1) (L-1 = 2-(pyrazol-1-ylmethyl)pyridine) is described. Treatment of 1 with (i) Ag(CF3SO3) in CH3CN and (ii) NaN3 in CH3OH, and (iii) the reaction between [(eta(6)-C6H6)Ru(L-2)Cl][PF6] (2) (previously reported) and NaCN in C2H5OH led to the isolation of [(eta(6)-C6H6)Ru(L-1)(CH3CN)][PF6](2) (3), [(eta(6)-C6H6)Ru(L-1)(N-3)][PF6] (4), and [(eta(6)-C6H6)Ru(L-2)(CN)][PF6] (5), respectively (L-2 = 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine). The complex [(eta(6)-C6H6)Ru(L-4)Cl][PF6] (6) with a new ligand (L-4 2-[3-(4-fluorophenyl) pyrazol-1-ylmethyl]pyridine) has also been synthesized. The structures of 3-6 have been elucidated ((1)HNMRspectra; CD3CN). The molecular structures of 1, 4, and 6 center dot C6H5CH3 have been determined. Notably, the crystal-packing in these structures is governed by C-H center dot center dot center dot X (X = Cl, N) interactions, generating helical architectures. (C) 2010 Published by Elsevier B.V.