Synthesis and characterisation of alkaline earth bis(diphenylphosphano)metallocene complexes and heterobimetallic alkaline earth metal/platinum(II) complexes [Ae(thf)(x)(eta(5)-C5H4PPh2)(2)Pt(Me)(2)] (Ae = Ca, Sr, Ba)

Daisy Daniels, Glen Berenger Deacon, Dominique Harakat, Florian Jaroschik, Peter Courtney Junk

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A series of alkaline earth metallocene complexes carrying the diphenylphosphanocyclopentadienyl ligand, [Ae(L)(x)(eta(5)-C5H4PPh2)(2)] (Ae = Ca, L = thf, x = 1 (6a); Ae = Ca, L = dme, x = 1 (6b); Ae = Sr, L = thf, x = 1 (7); Ae = Ba, L = thf, x = 1 (8a); Ae = Ba, L = dme, x = 2 (8b)), were prepared by redox transmetallation/protolysis from the free metals, diphenylmercury and diphenylphosphano-cyclopentadiene. These complexes were characterised using multinuclear NMR spectroscopy and two by single crystal X-ray diffraction. [Ca(dme)(eta(5)-C5H4PPh2)(2)] (6b) is a discrete neutral monomeric eight coordinate molecule in which the phosphorus atoms are not coordinated to the calcium ion and the larger barium analogue, ten-coordinate [Ba(dme)(2)(eta(5)-C5H4PPh2)(2)] (8b), has an extremely bent sandwich structure due to the two dme ligands attached to the metal. Bimetallic complexes, [Ae(thf)(x)(eta(5)-C5H4PPh2)(2)Pt(Me)(2)]center dot(solv) (Ae = Ca, L = thf, x = 2, solv = 1.5thf (9); Ae = Sr, L = thf, x = 3, solv = 1.5thf (10); Ae = Ba, L = thf, x = 3, solv = thf (11)) were obtained by reaction of the homometallic complexes with [Pt(cod)(Me)(2)]. The crystal structures of [Ca(thf)(2)(eta(5)-C5H4PPh2)(2)Pt(Me)(2)].1.5thf (9), [Sr(thf)(3)(eta(5)-C5H4PPh2)(2)Pt(Me)(2)]. 1.5thf (10) and [Ba(thf)(3)(eta(5)-C5H4PPh2)(2)Pt(Me)(2)].thf (11) show the eight (calcium) and nine coordinate (strontium and barium) fragments acting as a chelating metalloligand attached to the square planar platinum through the phosphorus donor atoms. The solution chemistry of these bimetallic complexes has been investigated by NMR spectroscopy, electro-spray ionisation mass spectrometry and conductivity experiments which indicate that the bimetallic compounds persist in solution.
Original languageEnglish
Pages (from-to)267 - 277
Number of pages11
JournalDalton Transactions
Issue number1
Publication statusPublished - 2012

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