PART I: THE X-RAY PHOTOELECTRON SPECTRA OF TRANSITION METAL COMPLEXES. PART II: THE SYNTHESIS AND SUBSTITUTION CHEMISTRY OF ISOCYANIDE COMPLEXES OF GROUP VI B

WILLIAM STANLEY MIALKI, Purdue University

Abstract

Part I. The metal core binding energies of sixteen complexes of Mo(II) containing the {((eta)('3)-allyl)Mo(CO)(,2)} moiety have been recorded. These data were compared with literature data for complexes of the types Mo(CO)(,5)L, Mo(CO)(,4)L(,2) and Mo(CO)(,3)L(,3). In contrast to the conclusions of other workers, the present work shows that the Mo 3d energies are not dependent in any simple way upon the number of carbonyl groups bonded to the molybdenum. The XPS was employed to study pairs of mononuclear Cu(II) and Cu(I) complexes of several macrocyclic ligands. It was demonstrated that there is a chemical shift of (TURN)2.5 eV between the Cu 2p binding energies of these two oxidation states. Comparison of these data with the Cu2p binding energies of Cu('I)(TAAB)(NO(,3)), where TAAB is the cyclotetrameric Schiff base of o-aminobenzaldehyde, support the contention that the latter complex is a genuine Cu(I) species rather than the alternative formulation of this complex as one containing Cu(II) or Cu(III) bound to a reduced ligand. Two additional studies employing the XPS technique were that of the satellite structure of transition metal complexes of alkyl and aryl isocyanides and a study of silica supported rhodium, XPS provided information concerning the oxidation state of the rhodium. Part II. Prompted by the successful use of Mo(,2)(O(,2)CCH(,3))(,4) as a convenient starting material for the synthesis of homoleptic alkyl isocyanide complexes, analogous reactions were investigated using W(,2)(mhp)(,4), where mhp is te anion of 2-hydroxy-6-methylpyridine. This procedure proved to be a convenient route to the {W(CNR)(,7)}('2+) cations, as well as establishing further the generality of the cleavage of multiple metal-metal bonds by (pi)-acceptor ligands. In contrast, the reaction of Cr(,2)(mhp)(,4) and Cr(,2)(O(,2)CCH(,3))(,4) with alkyl isocyanides did not lead to any characterizable products. Subsequently, it was discovered that the reactions of ethanolic solutions of Cr(II) with alkyl isocyanides leads to formation of the six and seven coordinate complexes {Cr(CNR)(,6 or 7)}('2+). These isocyanide complexes were shown to have a rich substitution chemistry toward phosphines and NO(,(g)). The products isolated were {Cr(CNR)(,3+x)(dppe)} (PF(,6))(,2) where x = 1 or 2, {Cr(CNR)(,4)(PEt(,3))(,2)}(PF(,6))(,2) and {Cr(CNR)(,4)(NO)(,2)}(PF(,6))(,2) where R = CMe(,3) or C(,6)H(,11).

Degree

Ph.D.

Subject Area

Chemistry

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