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Reactivity of Seventeen- and Nineteen-Valence Electron Complexes in Organometallic Chemistry

1986; Taylor & Francis; Volume: 5; Issue: 5 Linguagem: Inglês

10.1080/02603598608079840

1548-9574

A. E. Stiegman, David R. Tyler,

Metal complexes synthesis and properties

Abstract Organometallic chemistry has traditionally been the domain of diamagnetic complexes and the powerful 16- and 18-electron rule.1 This rule, as set forth by Tolman,1(a) states that "… diamagnetic organometallic complexes of transition metals may exist in a significant concentration at moderate temperature only if the metal's valence shell contains 16 or 18 electrons." Furthermore, the rule states that "organometallic reactions, including catalytic ones, proceed by elementary steps involving only intermediates with 16 or 18 metal valence electrons." Although the rule is enormously useful for predicting the stability and reactivity of diamagnetic complexes, the range of organometallic chemistry has expanded in recent years to include numerous paramagnetic 17-valence electron complexes, which exist as both stable complexes and short-lived intermediates.2,3,4 These species, essentially metal-centered radicals, are typified by complexes such as Mn(CO)5, Mn(CO)3(PR3)2, Co(CO)4, and CpMo(CO)3 (Cp=η5−C5H5).