Synthesis, structural characterization and solvatochromic studies of a series of Schiff base-containing triosmium alkylidyne carbonyl clusters

A series of new Schiff base-containing triosmium alkylidyne carbonyl cluste rs [Os-3(mu-H)(2)(CO)(9)(mu(3)-CNC5H4CH=NC6H4R)] (R = H, NMe2, SMe, CMe3, N H2, Br, Cl, OCnH2n + 1, n = 1, 6, 7 or 9) have been prepared by reaction of [Os-3(mu-H)(3)(CO)(9)(mu(3)-CCl)] with one equivalent of 1,8-diazabicyclo[ 5.4.0]undec-7-ene in the presence of a ten-fold excess of the Schiff base l igands NC5H4CH=NC6R4R at room temperature. Analogous triosmium carbonyl clu sters bearing 4'-methoxy-4-stilbazole or 4-(4-nitrobenzyl)pyridine moiety a t the apical carbon centre have also been synthesized using 3 similar depro tonation method. The molecular structures of selected complexes have been e stablished by X-ray crystallography. UV-vis spectroscopy suggests that this class of compounds displays significant negative solvatochromic effect in an organic medium. (C) 1999 Elsevier Science S.A. All rights reserved.