Polynuclear silver complexes of 2,5-dimethyl-2,5-diisocyanohexane (TMB). Influence of the anions

Abstract

Two series of complexes have been prepared by reaction of 2,5-dimethyl-2,5-diisocyanohexane (TMB) with AgX [Formula: see text]. Complexes of the first series, Ag(TMB)X, have been obtained with [Formula: see text]. The structures have been determined by X-ray diffraction for [Formula: see text] and [Formula: see text]. The crystals contain infinite chains of silver atoms alternating with bridging TMB ligands. When [Formula: see text], the Ag atom is best described as (2 + 2)-coordinated, with two of the coordination sites filled by [Formula: see text] acting as a bidentate ligand. When [Formula: see text], the Ag—TMB chain is of a different type and Ag can be considered two-coordinated and weakly interacting with a monodentate [Formula: see text] ion. The second series includes Ag2(TMB)3X2 complexes whose structure consists of pairs of chains cross-linked by extra TMB ligands leading to a ladder-like pattern. A weak unidentate interaction involving [Formula: see text] or [Formula: see text] is also apparent. The infrared data are in agreement with the X-ray results, since the highest v(C≡N) value is obtained for Ag(TMB)BF4, where Ag—CN distance is the shortest. The conformation of TMB is always trans about the central CH2—CH2 bond. The methyl groups render one of the staggered orientations of the —C(CH3)2(NC) groups unfavorable, leaving two conformations for coordinated TMB, both of which are observed in the Ag complexes.