Investigation of paramagnetic species formed during the thermolysis, photolysis, and oxygenation of some bi- and tri-nuclear organometallic compounds of chromium, iron, and molybdenum

Laurence Carlton, W. Edward Lindsell, Peter N. Preston

Research output: Contribution to journalArticle

Abstract

Oxygenation of the products derived thermally (-70 °C) from [Cr2(?-C5H5)2(CO)6] (1 a) or photochemically from [Hg{Cr(?-C5H5)(CO)3}2] (2a) or [{(?-C5H5)Cr(CO)3Cu(phen)}n] (3; phen = 1,10-phenanthroline) gives rise to a paramagnetic species [Cr(?-C5H5)(CO)n(O2)] (n = 3), most probably containing a peroxo-ligand and with n = 2. Evidence in support of the structure of this dioxygen complex is adduced from, among other things, experiments using 2H- and 17O-labelled precursors. Attempts to identify an intermediate in the reaction of (1a) by using the spin-trapping agents RNO (R = But or C6Me4H) have produced paramagnetic species believed to be side-on bonded nitroso-complexes [Cr(?-C5H5)(CO)2(ONR)] (4b); when R = But this complex decomposes thermally to form But2NO and a possible mechanism for this process is discussed. The solution photolyses are described of derivatives (7), [Fe(?-C5H5)(CO)(L)X] [L = CO, X = Fe(?-C5H5)(CO)2, HgFe(?-C5H5)(CO)2, SnPh3, or PbPh3; L = PPh3 or alkene, X = SnPh3], in vacuo with and without added nitrosodurene and also in the presence of air or dioxygen. E.s.r. parameters of the resulting paramagnetic products are reported and discussed. Iron-aminyl oxide complexes are formed with nitrosodurene at -40 °C but at higher temperatures (ca. -10 to +20 °C) photolyses of complexes (7d), (7e), and (7i) (L = CO or PPh3, X = SnPh3; L = CO, X = PbPh3) form a nitroxide (C5H5)NO(C6Me4H) resulting from Fe-(?-C5H5) bond fission. Also, when X = SnPh3 (7d) and (7f)-(7h) or X = PbPh3(7i) photolysis in vacuo produces paramagnetic iron derivatives which contain the Group 4B metal and the nature of these products is discussed. Solution photolyses of complexes (11), [Mo(?-C5H5)(CO)2(L)X] [L = CO, X = Mo(?-C5H5)(CO)3, HgMo(?-C5H5)(CO)3, or CdMo(?-C5H5)(CO)3; L = PPh3, X = HgMo(?-C5H5)(CO)(PPh3)], are described; e.s.r. data are presented for paramagnetic products arising from reaction with nitrosodurene in vacuo and from oxygenation.

Original languageEnglish
Pages (from-to)1483-1489
Number of pages7
JournalJournal of the Chemical Society, Dalton Transactions
Issue number8
DOIs
Publication statusPublished - 1982

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