Reduktive Aktivierung des Metallaheterocyclobutadienkomplexes Fe(CO)3

Article abstract of DOI:10.1016/0022-328X(90)80068-B

The compound Fe(CO)3 (1a) may be described as an Fe(Co)3 derivative of a 1,2-ferrathiacyclobutadiene ligand.The CO groups of 1a, which are very difficult to substitute by thermal activation. are readily exchanged when compared with P(OMe)3, by reductive electrocatalysis.Reductive initiation of substitution is also possible by the reduction of 1a with Na/Hg or t-BuLi.The mechanism of the reductively-initiated formation of the products 1b and 1c, in which one or two carbonyl groups, respectively, of 1a are replaced by P(OMe)3 as well as the formation of a monosubstituted derivative of 1a, in which an axial CO group of the heterometallacyclobutadiene ligand is replaced by ^tBuP(OMe)2 (1d) is discussed with respect to electrochemical, spectroscopic and structural data. ^tBuLi can activate 1a not only by single electron transfer: the addition of ^tBu^- at the sulfur center of 1a leads to an anionic CI-insertion product, which,by subsequent alkylation, may be trapped as Fe(CO)3<η⁴-(CO)3(t-Bu)> (2b).Insertion of CO in 1a is also initiated by Na/Hg reduction; oxidative work up with I₂ gives Fe(CO)3<η⁴-(CO)3>(3).Thermal activation readily decarbonylates 3 to give 1a.The individual results are consistently described in a common reaction scheme.The structures of 1d, 2 and 3 have been determined by X-ray diffraction studies.