[η2-Bis(di-t-butylphosphino)methan](trans-stilben)nickel(0), Ni(dtbpm)(trans-PhCH = CHPh). Synthese und Molekülstruktur einer Vorstufe des 14-Elektronenfragments [Ni(dtbpm)] / [η2-Bis(di-t-butylphosphino)methane](trans-stilbene)nickel(0), Ni(dtbpm)(trans-PhCH=CHPh). Synthesis and Molecular Structure of a Precursor for the 14-Electron Fragment [Ni(dtbpm)]

Abstract

The synthesis of [η2-bis(di-t-butylphosphino)methane](trans-stilbene)nickel(0), Ni(dtbpm)(trans-PhCH=CHPh) (17), is reported. This novel, stable Ni(0)-olefin complex can be prepared from dichloro[η2-bis(di-t-butylphosphino)methane]nickel(II), Ni(dtbpm)Cl2 (18), which is easily accessible from anhydrous NiCl2 and bis(di-t-butylphosphino)methane, (dtbpm, 12). Lithium-powder reduction of 18 in the presence of an excess of trans-stilbene in ether at low temperature yields 17. For both 17 and 18 X-ray structure determinations have been carried out and the results for the olefin complex 17 are reported and discussed in detail. 17 is the first bisphosphane Ni(0) olefin complex in which the d10 metal is part of a four-mem-bered bisphosphane chelate ring with an accordingly very small P—Ni—P angle (79.6°). The molecular geometry of 17 reveals electronic structure characteristics, bonding capabilities and steric properties for the Ni(dtbpm)-unit, which are in accord with previous theoretical predictions. 17 can serve as a convenient precursor to generate the strongly bent d10-ML2 14-electron fragment [Ni(dtbpm)] (13) in solution. This reactive intermediate can be trapped, yielding various derivatives of the stereoelectronically anomalous Ni(0) fragment 13.