pentacarbonyltungsten complex and dimethyl acetylenedicarboxylate can be used as a precursor for the methylphosphaketene tungsten complex under UV irradiation at room temperature. Under these conditions, the phosphaketenecomplex easily loses CO to give the methylphosphinidene complex. Highly reactive alcohols and primary alkylamines trap both the phosphaketene and the phosphinidene complexes. Less reactive
作者:Mark L. G. Borst、Rosa E. Bulo、Danièle J. Gibney、Yonathan Alem、Frans J. J. de Kanter、Andreas W. Ehlers、Marius Schakel、Martin Lutz、Anthony L. Spek、Koop Lammertsma
DOI:10.1021/ja054885w
日期:2005.12.1
The synthesis of a variety of benzophosphepine complexes [R = Ph, t-Bu, Me; MLn = W(CO)(5), Mo(CO)(5), Cr(CO)(5), Mn(CO)(2)Cp] by two successive hydrophosphinations of 1,2-diethynylbenzene is discussed in detail. The first hydrophosphination step proceeds at ambient temperature without additional promoters, and subsequent addition of base allows full conversion to benzophosphepines. Novel benzeno-1,4-diphosphinanes were isolated as side products. The benzophosphepine complexes themselves serve as convenient phosphinidene precursors at elevated, substituent-dependent temperatures (> 55 degrees C). Kinetic and computational analyses support the proposal that the phosphepine-phosphanorcaradiene isomerization is the rate-determining step. In the absence of substrate, addition of the transient phosphinidene to another benzophosphepine molecule is observed, and addition to 1,2-diethynylbenzene furnishes a delicate bidentate diphosphirene complex.
Generation and trapping of terminal phosphinidene complexes. Synthesis and x-ray crystal structure of stable phosphirene complexes