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Reaction Chemistry of Complexes Containing PtH, PtSH, or PtS Fragments: From Their Apparent Simplicity to the Maze of Reactions Underlying Their Interconversion

The relevance of platinum in the reaction of thiophene and derivatives with homogeneous transition‐metal complexes as models for hydrodesulfurization has led us to the study of the reaction chemistry of complexes containing PtH, PtSH, and PtS fragments. Exploration of the reactions triggered by a...

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Published in:Chemistry : a European journal 2007-01, Vol.13 (4), p.1047-1063
Main Authors: Novio, Fernando, González-Duarte, Pilar, Lledós, Agustí, Mas-Ballesté, Rubén
Format: Article
Language:English
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Summary:The relevance of platinum in the reaction of thiophene and derivatives with homogeneous transition‐metal complexes as models for hydrodesulfurization has led us to the study of the reaction chemistry of complexes containing PtH, PtSH, and PtS fragments. Exploration of the reactions triggered by addition of controlled amounts of Na2S or NaSH to [Pt2(H)2(μ‐H)(dppp)2]ClO4 (1) has provided evidence of the formation of complexes [Pt2(μ‐H)(μ‐S)(dppp)2]ClO4 (2), [Pt(H)(SH)(dppp)] (3), [Pt2(μ‐S)2(dppp)2] (4), [Pt2(μ‐S)(dppp)2] (5) and [Pt(SH)2(dppp)], in which dppp denotes 1,3‐bis(diphenylphosphanyl)propane. Consequently, complexes 1, 2, and 5 as well as the already reported 3, 4, and [Pt(SH)2(dppp)] have been obtained and fully characterized spectroscopically. Also the crystal structures of 1 and 2 have been solved. Complexes 1–5 constitute the main framework of the network of reactions that account for the evolution of 1 under various experimental conditions as shown in Scheme 1. Apparently, this network has complexes 2 and 4 as dead‐ends. However, their reciprocal interconversion by means of the replacement of one bridging hydride or sulfide ligand in the respective {Pt(μ‐H)(μ‐S)Pt} and {Pt(μ‐S)2Pt} cores enables the closure of the reaction cycle involving complexes 1–5. Theoretical calculations support the existence of the undetected intermediates proposed for conversion from 1 to 2 and from 3 to 2 and also account for the fluxional behavior of 1 in solution. The intermediates proposed are consistent with the experimental results obtained in comparable reactions carried out with labeled reagents, which have provided evidence that complex 1 is the source of the hydride ligands in complexes 2 and 3. Overall, our results show the strong dependence on the experimental conditions for the formation of complexes 1–5 as well as for their further conversion in solution. La importància del platí en les reaccions del tiofè i llur derivats amb complexos de metalls de transició en fase homogènia, les quals es consideren models del procés de hidrodesulfuració, ens ha dut a l'estudi de la química de complexos que contenen els fragments PtH, PtSH i PtS. L'exploració de les reaccions que es desencadenen per addició de quantitats controlades de Na2S o NaSH a [Pt2(H)2(μ‐H)(dppp)2]ClO4 (1) ha fet palesa la formació de [Pt2(μ‐H)(μ‐S)(dppp)2]ClO4 (2), [Pt(H)(SH)(dppp)] (3), [Pt2(μ‐S)2(dppp)2] (4), [Pt2(μ‐S)(dppp)2] (5) i [Pt(SH)2(dppp)], on dppp representa 1,3‐bis(difenilfosf
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.200600693