Reductive dehalogenation of chloro(alkynyl)phosphines by octacarbonyldicobalt

Article abstract of DOI:10.1016/0022-328X(91)83011-R

Reductive dehalogenation of the (chloro)(phenylethynyl)phosphine (2,4,6-^tBu3C6H2O)(PhC<*>C)PCl, I, by Co2(CO)8, II, yields the neutral phosphenium ion complex <(R)(R')>P=Co(CO)3, III, (R = 2,4,6-^tBu3C6H2O; R' = (η²-C<*>CPh)Co2(CO)6), which contains a trigonally planar coordinated phosphorus atom.When NaCo(CO)4, V, is used instead of II a dinuclear complex, Co2(CO)6<μ²-P(R)(R')>2, VI, (R = 2,4,6-^tBu3C6H2O; R' = C<*>CPh) is formed in which the phosphido ligands P(R)(R'), bridge in a μ₂ fashion two Co(CO)3 units.The mechanism of formation of VI, involvinga formal dimerization of two <(2,4,6-^tBu3C6H2O)(PhC<*>C)>P=Co(CO)3 fragments, is discussed.However, (^tBu)(PhC<*>C)PCl, VII, reacts with II, to yield the cluster compound VIII, containing the two μ₂-bridging units (^tBu)<(η²-C<*>CPh)Co2(CO)5>P and (^tBu)(PhC<*>C)P.Compounds III and VI-VIII were identified from their analytical and spectroscopic (IR, 1H-, 13C- and 31P-NMR) data.The molecular structure of the cluster compound VIII was determined by an X-ray diffraction study.