Caruso, Francesco, Chan, Eric J., Hanna, John V., Marchetti, Fabio, Pettinari, Claudio, Di Nicola, Corrado, Pettinari, Riccardo, Pizzabiocca, Adriano, Rees, Gregory J., Quigley, David, Rossi, Miriam, Skelton, Brian W., Sobolev, Alexandre N. and White, Allan H.. (2012) The question of cis versus trans configuration in Octahedral Metal Diketonates : an in-depth investigation on Diorganobis(4-acyl-5-pyrazolonato)tin(IV) complexes. European Journal of Inorganic Chemistry, Vol.2012 (No.9). pp. 1369-1379. ISSN 1434-1948

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Abstract

Diorganotin(IV) derivatives of 4-acyl-5-pyrazolones Q2SnR2 [HQ = 3-methyl-1-phenyl-4-R-5-pyrazolone: HQnPe, R = neopentylcarbonyl; HQiPr, R = isopropylcarbonyl; HQtBu, R = tert-butylcarbonyl; HQCy, R = cyclohexylcarbonyl; HQCp, R = cyclopentylcarbonyl; HQEtCp, R = (ethylcyclopentyl)carbonyl] have been synthesized and characterized spectroscopically (IR, far-IR, 1H, 13C and 119Sn NMR) and structurally (X-ray). Steric bulkiness in the acyl fragment of HQtBu induces partial dissociation in solution of (QtBu)2SnMe2, which exists as an equilibrium mixture of six- and five-coordinate tin species. Single-crystal X-ray structure determinations of several representative complexes are presented. Whereas the dialkyltin(IV) complexes are always trans-octahedral, a diphenyltin(IV) derivative exists in the solid state that has the two phenyl groups in a cis arrangement. DMol3 and CASTEP DFT studies of this unprecedented cis, and the corresponding trans configurations, show the former to be slightly more stable, in agreement with the diffraction study. Solid-state 119Sn cross-polarization magic-angle spinning NMR spectroscopic data show that the isotropic chemical shifts (δiso,mas) and chemical-shift anisotropies/spans (Δδ/Ω) that characterize the diphenyl(IV) derivatives are markedly removed from values measured for the corresponding dimethyl and di-n-butyl derivatives, thereby adding further evidence for a stable cis configuration in the diphenyl(IV) systems. This is supported by GIPAW DFT calculation of the 119Sn isotropic shifts and chemical-shift anisotropies/spans from fully relaxed structures by using the CASTEP code, which provides a direct link between the cis diphenyl(IV) arrangement and the reported differences in the 119Sn NMR spectroscopic parameters.

Item Type:	Journal Article
Divisions:	Faculty of Science > Physics
Journal or Publication Title:	European Journal of Inorganic Chemistry
Publisher:	Wiley-VCH Verlag GMBH
ISSN:	1434-1948
Date:	2012
Volume:	Vol.2012
Number:	No.9
Page Range:	pp. 1369-1379
Identification Number:	10.1002/ejic.201101050
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
URI:	http://wrap.warwick.ac.uk/id/eprint/48607

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