Contrasting the group 6 metal-metal bonding in sodium dichromate(II) and sodium dimolybdate(II) polymethyl complexes: synthetic, X-ray crystallographic and theoretical studies

Campbell, R., Kennedy, A. R., McLellan, R., Robertson, S. D., Sproules, S. and Mulvey, R. E. (2017) Contrasting the group 6 metal-metal bonding in sodium dichromate(II) and sodium dimolybdate(II) polymethyl complexes: synthetic, X-ray crystallographic and theoretical studies. Dalton Transactions, 46(17), pp. 5650-5659. (doi:10.1039/C6DT04644D) (PMID:28145549)

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Abstract

Extending the class of group 6 metal–metal bonded methylate compounds supported by alkali metal counter-ions, the first sodium octamethylmolybdate(II) complex [(TMEDA)Na]4Mo2Me8 and heptamethylchromate(II) relations [(donor)Na]3Cr2Me7 (donor is TMEDA or TMCDA) are reported. The former was made by treating [(Et2O)Li]4Mo2Me8 with four equivalents of NaOtBu/TMEDA in ether; whereas the latter resulted from introducing TMEDA or TMCDA to ether solutions of octamethyldichromate [(Et2O)Na]4Cr2Me8. X-ray crystallography revealed [(TMEDA)Na]4Mo2Me8 is dimeric with square pyramidal Mo centres [including a short Mo–Mo interaction of 2.1403(3) Å] each with four methyl groups in a mutually eclipsed conformation. In dinuclear [(TMCDA)Na]3Cr2Me7 trigonal bi-pyramidal Cr centres each bond to three terminal methyl groups and one common Me bridge, that produces a strikingly short Cr–Cr contact of 1.9136(4) Å. Broken symmetry density functional theoretical calculations expose the multiconfigurational metal–metal bonding in these compounds with a Mo–Mo bond order of 3 computed for octamethylmolybdate(II). This is contrasted by the single Cr–Cr bond in heptamethylchromate(II) where the singlet ground state is derived by strong antiferromagnetic coupling between adjacent metal ions.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Sproules, Dr Stephen
Authors: Campbell, R., Kennedy, A. R., McLellan, R., Robertson, S. D., Sproules, S., and Mulvey, R. E.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Dalton Transactions
Publisher:Royal Society of Chemistry
ISSN:1477-9226
ISSN (Online):1477-9234
Published Online:26 January 2017
Copyright Holders:Copyright © 2017 The Royal Society of Chemistry
First Published:First published in Dalton Transactions 46(17): 5650-5659
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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