Synthesis and characterization of d2 imido complexes of molybdenum. Crystal structure of MoCl2{N(mes)}(PhC≡CPh)-(PMe3)2·0.5PhC≡CPh (mes = 2,4,6-trimethylphenyl)

摘要

The compound [MoCl2{N(mes)}(PMe3)3] 1 (mes = 2,4,6-trimethylphenyl) has been prepared by the reaction of [MoCl3{N(mes)}(dme)] (dme = 1,2-dimethoxyethane) with 2 equivalents of PMe3 and subsequent sodium amalgam reduction, in the presence of 1 additional equivalent of PMe3. Metathesis reactions of 1 with KX gave [MoX2{N(mes)}(PMe3)3] (X = Br 2 or NCS 3), whereas the anionic bidentate PriOCS2– ligand produced the monophosphine compound [Mo{N(mes)}(S2COPri)2(PMe3)] 4. Substitution of two of the PMe3 ligands to give [MoCl2{N(mes)}(PMe3)(depe)] 5 (depe = Et2PCH2CH2PEt2) is also feasible, whilst phosphites and other π acceptors provided the corresponding [MoCl2{N(mes)}L(PMe3)2] compounds [L = P(OMe)3 6, P(OCH2)3CCH2CH3 7, C2H4 8, H2C[double bond, length half m-dash]CHCO2Me 9, CO 10, CNBut 11, CNMe 12, PhC[triple bond, length half m-dash]CH 13 or PhC[triple bond, length half m-dash]CPh 14] by substitution of the unique PMe3 group of 1. Some of these arylimido complexes exhibit dynamic behaviour in solution, due to restricted rotation of the aryl group around the C–N bond. The molecular structure of 14 (as its PhC[triple bond, length half m-dash]CPh hemisolvate, i.e. 14·0.5PhC[triple bond, length half m-dash]CPh) has been determined by an X-ray study.