MECHANISTIC STUDY OF THE REACTION OF OS3(CO)10(CNPR)(NCME) WITH BRONSTED ACID

The reaction Of Os3(CO)10(CNPr)(NCMe) (1) with Bronsted acid in CH2Cl2 takes place initially via the protonation of 1 to yield the hydrido complex [(mu-H)OS3(CO)10(CNPr)(NCMe)]+ (2), followed by substitution of labile acetonitrile ligand with carboxylate anion to form the monodentate carboxylate complexes (mu-H)OS3(CO)10(CNPr)(eta1-OCOR) (3). Spectroscopic and crystallographic evidence is presented to explain mechanistic details of the reaction. Molecular structures of (mu-H)Os3(CO)10(CNPr)(eta1-OCOCF3) (3a) and (mu-H)OS3(CO)10(CNPr)(eta1-OCOC = CH) (3b) have been determined by X-ray diffraction studies, Crystal data: 3a: P2(1)/n; a = 11.6632(19), b = 14.7827(24), c = 14.487(3) angstrom; beta = 103.635(15), V = 2427.4(7) angstrom3, Z = 4, R = 5.2%, R(w) = 5.4%. 3b: P3(2); a = 14.853(3), c = 9.158(3) angstrom; V= 1749.6(7) angstrom3, Z = 3, R = 3.2%, R(w) = 3.8%.