Intramolecular hydrogen bonding controls 1,3-N,S- vs. 1,5-S,S′-coordination in NiII complexes of N-thiophosphorylated thioureas RNHC(S)NHP(S)(OiPr)2

Maria G. Babashkina; Damir A. Safin; Michael Bolte; Monika Srebro; Mariusz Mitoraj; André Uthe; Axel Klein; Martin Köckerling

doi:10.1039/C0DT01382J

Intramolecular hydrogen bonding controls 1,3-N,S- vs. 1,5-S,S′-coordination in Ni^II complexes of N-thiophosphorylated thioureas RNHC(S)NHP(S)(OiPr)₂†

Maria G. Babashkina,*^ab Damir A. Safin,^ab Michael Bolte,^c Monika Srebro,^d Mariusz Mitoraj,^d André Uthe,^b Axel Klein*^b and Martin Köckerling^a

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* Corresponding authors

^a Institut für Chemie, Anorganische Festkörperchemie, Albert-Einstein-Str., 3a, Rostock, Germany
E-mail: maria.babashkina@ksu.ru
Fax: +49 381 4986390
Tel: +49 381 4986381

^b Institut für Anorganische Chemie, Universität zu Köln, Greinstrasse 6, Köln, Germany
E-mail: axel-klein@uni-koeln.de
Fax: +49 221 4705196
Tel: +49 221 4702913

^c Institut für Anorganische Chemie J.-W.-Goethe-Universität, Frankfurt/Main, Germany

^d Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University, R. Ingardena 3, Cracow, Poland

Abstract

Reaction of the deprotonated N-thiophosphorylated thioureas RNHC(S)NHP(S)(OiPr)₂ (R = Ph, HL^I; 2-MeC₆H₄–, HL^II; 2,6-Me₂C₆H₃–, HL^III; 2,4,6-Me₃C₆H₂–, HL^IV; Me–, HL^V) with Ni^II leads to complexes of the formula [NiL^I^–V₂]. The molecular structures of the thioureasHL^II–V and the complexes [NiL^II^–V₂] in the solid were elucidated by single-crystal X-ray diffraction analysis. In the complexes, the metal is found to be in a square planar trans-N₂S₂ ([NiL^II–IV₂]) environment formed by the C [double bond, length as m-dash] S sulfur atoms and the P–N nitrogen atoms, or in a square planar trans-S₂S′₂ ([NiL^V₂]) environment formed by the CS and PS sulfur atoms of two deprotonated ligands. DFT calculations confirmed that the [Ni(L^II–IV-N,S)₂] isomers are more stable (by 16–21 kcal mol⁻¹) than the corresponding [Ni(L^II–IV-S,S′)₂] conformers. The main reason for higher stability of the 1,3-N,S vs. 1,5-S,S′ isomers is the formation of intramolecular N–H⋯S [double bond, length as m-dash] P hydrogen bonds. In solution the complexes [Ni(L^II–V-N,S)₂] have an exclusive 1,3-N,S coordination, while the compound [Ni(L^I-N,S)₂] exhibits two isomers in the ¹H and ³¹P NMR spectra. The major species is assigned to the 1,3-N,S coordinated isomer, while the minor (∼25%) signals are due to the 1,5-S,S′ isomer. UV-Vis spectroscopic results are in line with this. The electrochemical measurements reveal reversible one-electron reduction and irreversible oxidations, both assigned to ligand-centred processes.

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Article information

DOI: https://doi.org/10.1039/C0DT01382J
Article type: Paper
Submitted: 13 Oct 2010
Accepted: 13 Dec 2010
First published: 18 Feb 2011

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Dalton Trans., 2011,40, 3142-3153

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Intramolecular hydrogen bonding controls 1,3-N,S- vs. 1,5-S,S′-coordination in Ni^II complexes of N-thiophosphorylated thioureas RNHC(S)NHP(S)(OiPr)₂

M. G. Babashkina, D. A. Safin, M. Bolte, M. Srebro, M. Mitoraj, A. Uthe, A. Klein and M. Köckerling, Dalton Trans., 2011, 40, 3142 DOI: 10.1039/C0DT01382J

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