2-(methylamido)pyridine–borane : a tripod κ3N,H,H-ligand in trigonal bipyramidal rhodium(I) and iridium(I) complexes with an asymmetric coordination of its BH3 group

Brugos, Javier and Cabeza, Javier A. and Garcia-Álvarez, Pablo and Kennedy, Alan R. and Pérez-Carreño, Enrique and Van der Maelen, Juan F. (2016) 2-(methylamido)pyridine–borane : a tripod κ3N,H,H-ligand in trigonal bipyramidal rhodium(I) and iridium(I) complexes with an asymmetric coordination of its BH3 group. Inorganic Chemistry, 55 (17). pp. 8905-8912. ISSN 0020-1669 (https://doi.org/10.1021/acs.inorgchem.6b01427)

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Abstract

The complexes [M(κ3N,H,H-mapyBH3)(cod)] (M = Rh, Ir; HmapyBH3 = 2-(methylamino)pyridine–borane; cod = 1,5-cyclooctadiene), which contain a novel anionic tripod ligand coordinated to the metal atom through the amido N atom and through two H atoms of the BH3 group, have been prepared by treating the corresponding [M2(μ-Cl)2(cod)2] (M = Rh, Ir) precursor with K[mapyBH3]. X-ray diffraction studies and a theoretical QTAIM analysis of their electron density have confirmed that the metal atoms of both complexes are in a very distorted trigonal bipyramidal coordination environment, in which two equatorial sites are asymmetrically spanned by the H–B–H fragment. While both 3c–2e BH–M interactions are more κ1H (terminal sigma coordination of the B–H bond) than κ2H,B (agostic-type coordination of the B–H bond), one BH–M interaction is more agostic than the other and this difference is more marked in the iridium complex than in the rhodium one. This asymmetry is not evident in solution, where the cod ligand and the BH3 group of these molecules participate in two concurrent dynamic processes of low activation energies (VT-NMR and DFT studies), namely, a rotation of the cod ligand that interchanges its two alkene fragments (through a square pyramidal transition state) and a rotation of the BH3 group about the B–N bond that equilibrates the three B–H bonds (through a square planar transition state). While the cod rotation has similar activation energy in 2 and 3, the barrier to the BH3 group rotation is higher in the iridium complex than in the rhodium one.

  • Item type:Article
    ID code:57310
    Dates:
    Date
    Event
    12 October 2016
    Published
    12 August 2016
    Published Online
    30 July 2016
    Accepted
    Notes:This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/journal/inocaj
    Subjects:Science > Chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:08 Aug 2016 12:04
    Last modified:21 Apr 2024 00:26
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/57310
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