Issue 3, 2020

Relative hemilabilities of H2B(az)2 (az = pyrazolyl, dimethylpyrazolyl, methimazolyl) chelates in the complexes [M(η-C3H5)(CO)2{H2B(az)2}] (M = Mo, W)

Abstract

The reactions of [M(η3-C3H5)Br(CO)2(NCMe)2] (M = Mo, W) or [Mo(η3-C3H5)Br(CO)2(PMe2Ph)2] with Na[H2B(mt)2] (mt = methimazolyl) affords the complexes [M(η3-C3H5)(CO)23-H,S,S′-H2B(mt)2}], the 3-centre, 2-electron B–H–M interaction of which was found to be inert with respect to opening under mild conditions, while more forcing conditions (heating with PMe2Ph) resulted in cleavage of the entire allyl and borate ligands to form [Mo(CO)3(PMe2Ph)3]. In contrast, the reaction of [Mo(η3-C3H5)Br(CO)2(NCMe)2] with Na[H2B(pz)2] affords either [Mo(η3-C3H5)(CO)23-H,N,N′-H2B(pz)2}] or (more likely) [Mo(η3-C3H5)(CO)2(NCMe){κ2-N,N′-H2B(pz)2}] which in turn reacts with phosphines to provide [[Mo(η3-C3H5)(CO)2(PPhR2){κ2-N,N′-H2B(pz)2}] (R = Me, Ph). The reactions discussed indicate the propensity for 3-centre, 2-electron B–H–Mo interactions increases in the order H2B(pz)2 < H2B(pz*)2 < H2B(mt)2 (pz* = 3,5-dimethypyrazolyl).

Graphical abstract: Relative hemilabilities of H2B(az)2 (az = pyrazolyl, dimethylpyrazolyl, methimazolyl) chelates in the complexes [M(η-C3H5)(CO)2{H2B(az)2}] (M = Mo, W)

Supplementary files

Article information

Article type
Paper
Submitted
20 Sep 2019
Accepted
11 Nov 2019
First published
12 Nov 2019

Dalton Trans., 2020,49, 781-796

Relative hemilabilities of H2B(az)2 (az = pyrazolyl, dimethylpyrazolyl, methimazolyl) chelates in the complexes [M(η-C3H5)(CO)2{H2B(az)2}] (M = Mo, W)

R. J. Abernethy, M. R. St.-J. Foreman, A. F. Hill, M. K. Smith and A. C. Willis, Dalton Trans., 2020, 49, 781 DOI: 10.1039/C9DT03744F

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