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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(3-C3H5)Br(CO)2(NCMe)2] (M = Mo, W) or [Mo(3-C3H5)(CO)2(PMe2Ph)2] with Na[H2B(mt)2] (mt = methimazolyl) affords the complexes [M(3-C3H5)(CO)2{3-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(3-C3H5)Br(CO)2(NCMe)2] with Na[H2B(pz)2] affords either [Mo(3-C3H5)(CO)2{3-H,N,N’-H2B(pz)2}] or (more likely) [Mo(3-C3H5)(CO)2(NCMe){2-N,N’-H2B(pz)2}] which in turn reacts with phosphines to provide [[Mo(3-C3H5)(CO)2(PPhR2){2-N,N’-H2B(pz)2}] (R = Me, Ph). The reactions discussed indicate the propensity for 3-centre, 2-electron B–H–Mo interactions to increase H2B(pz)2 < H2B(pz*)2 < H2B(mt)2 (pz* = 3,5-dimethypyrazolyl).

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Publication details

The article was received on 20 Sep 2019, accepted on 11 Nov 2019 and first published on 12 Nov 2019


Article type: Paper
DOI: 10.1039/C9DT03744F
Dalton Trans., 2019, Accepted Manuscript

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    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)

    A. Hill, R. J. Abernethy, M. Foreman, M. K. Smith and A. Willis, Dalton Trans., 2019, Accepted Manuscript , DOI: 10.1039/C9DT03744F

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