Thiazoline- and oxazoline-annulated (eta(1)-P)-1,3-azaphosphole-(pentacarbonyl)chromium, -molybdenum and -tungsten complexes

The heterocycles 2,3-dihydro-1,3-azaphospholo[5,1-b]thiazole 1 and -oxazole 4 react with [(THF)M(CO)(5)] 2 (M = Cr, Mo, W) selectively to give (eta(1) -P)-(2,3-dihydro-1,3-azaphospholo[5,1-b]thiazole and -oxazole)M(CO)(5) comp lexes 3 and 5, respectively. The compounds are structurally characterized b y NMR data which is discussed in relation to those of the free ligands. Sup ported by PM3 calculation of 1 and 4, the preference to eta(1)-P-coordinati on is discussed in terms of control by d(M) --> pi* back-bonding. (C) 1999 Elsevier Science S.A. All rights reserved.