Issue 9, 2010

Synthetic, structural and computational studies on adducts of the 4,1,2-SnC2B10 supraicosahedral stannacarborane

Abstract

The stannacarborane 1,2-μ-(CH2)3-4,1,2-closo-SnC2B10H10 (1) and its adducts with 2,2′-bipyridine (bipy), 1,10-phenanthroline (o-phen) and 4,4′-diphenyl-2,2′-bipyridine (Ph2bipy), 1,2-μ-(CH2)3-4-(bipy)-4,1,2-closo-SnC2B10H10 (2), 1,2-μ-(CH2)3-4-(o-phen)-4,1,2-closo-SnC2B10H10 (3) and 1,2-μ-(CH2)3-4-(Ph2bipy)-4,1,2-closo-SnC2B10H10 (4), respectively, together with the analogous compound 1,2-μ-{C6H4(CH2)2}-4-(bipy)-4,1,2-closo-SnC2B10H10 (5) have been prepared and characterised. In solution at ambient temperature, compounds 1–5 all display NMR spectra which are interpreted in terms of (time-averaged) Cs molecular symmetry, but whilst (effectively) Cs symmetry is retained in the structures of 2–5 in the crystal (i.e. henicosahedral cage structures are observed), 1 has a (C1-symmetric) docosahedral structure. A method for quantifying the “percentage docosahedral character” of 13-vertex 1,2-C2 heteroboranes is described, based on the angles around the C1C2B9B5 quadrilateral. The structures of “carbons adjacent”1–5 all reveal less slipping of the Sn atom (or {SnL2} fragment) across the C2B4 carborane face than has previously been observed in analogous “carbons apart” 4,1,6-closo-SnC2B10 species, a surprising result in the context of previous studies of slipping in icosahedral platinacarboranes. A computational study of “carbons adjacent” and “carbons apart” icosahedral and supraicosahedral platinacarboranes has revealed that the origin of this observation is steric control of the slipping distortion in both “carbons apart” species and in the “carbons adjacent” 13-vertex species, with orbital interactions proving dominant only in the case of the “carbons adjacent” icosahedral compound.

Graphical abstract: Synthetic, structural and computational studies on adducts of the 4,1,2-SnC2B10 supraicosahedral stannacarborane

Supplementary files

Article information

Article type
Paper
Submitted
29 Oct 2009
Accepted
02 Dec 2009
First published
27 Jan 2010

Dalton Trans., 2010,39, 2412-2422

Synthetic, structural and computational studies on adducts of the 4,1,2-SnC2B10 supraicosahedral stannacarborane

P. D. Abram, D. McKay, D. Ellis, S. A. Macgregor, G. M. Rosair and A. J. Welch, Dalton Trans., 2010, 39, 2412 DOI: 10.1039/B922644C

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