Multinuclear (31P, 77Se, 113Cd, 199Hg) magnetic resonance, electrospray mass spectrometric and electrochemical studies on the reactions of M(S2P{OEt}2)2 (M=Cd, Hg) with potentially bidentate mixed Group 15/Group 16 and Group 16 donor ligands

Alan M. Bond, Ray Colton, John C. Traeger, Justin Harvey

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Abstract

Extensive studies of the labile Hg(dtp)2/dpmSe (dtp=(S2P{OEt}2); dpmSe=Ph2P(Se)CH2PPh2) system by multinuclear magnetic resonance (NMR), electrospray mass spectrometry (ESMS) and electrochemical techniques show that in solution both Hg(dtp)2 itself and the mixed Hg(dtp)2/dpmSe system consist of many competing equilibria with the species being identified as dtp-, Hg(dtp)2, [Hg(dtp)3]-, [Hg2(dtp)3]+, dpmSe, Hg(dtp)2(dpmSe), [Hg(dtp)(dpmSe)]+ and [Hg(dtp)(dpmSe)2]+. NMR studies show that Hg(dtp)2 reacts with dpmSe in 1:1 molar proportions to give products which, at room temperature in dichloromethane solution, are labile with exchange of both types of ligand occurring. Upon cooling to -30 °C the dpmSe ligand becomes chelated and static on the NMR timescale, but the dithiophosphate ligands still undergo rapid exchange. Further cooling causes the exchange of the dithiophosphate ligands to become slow and two species are observed at -100 °C which are identified as [(η2-dpmSe)Hg(η2-dtp)][S2P(OEt)2] and (η2-dpmSe)Hg(η1-dtp)2. ESMS studies on solutions of Hg(dtp)2 show the presence of dtp-, [Hg(dtp)3]- and [Hg2(dtp)3]+ and, after addition of dpmSe to the solution, ESMS confirmed the presence of [Hg(dtp)(dpmSe)]+. Differential pulse and direct current sampled polarograms re-emphasise the labile nature of this system and provide further evidence of mixed ligand compound formation as well as thermodynamic data. NMR studies on the Cd(dtp)2/dpmSe system show it to be more labile than its mercury analogue and the interpretation of the NMR data is ambiguous. NMR studies on the M(dtp)2/dpmS (or dpmSe2 or dpmS2) systems (MHg, Cd; dpmSe2 or dpmS2=Ph2P(E)CH2P(E)Ph2; ESe, S) are even less definitive. ESMS confirms the presence in solution of the cations [(ligand)M(dtp)]+ for all the systems studied.

Original languageEnglish
Pages (from-to)137-146
Number of pages10
JournalInorganica Chimica Acta
Volume224
Issue number1-2
DOIs
Publication statusPublished - Oct 1994

Keywords

  • Bidentate ligand complexes
  • Cadmium complexes
  • Electrochemistry
  • Electrospray mass spectrometry
  • Mercury complexes
  • Multinuclear NMR

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