Publications [#233751] of Richard A. Palmer

Journal Articles

  1. Palmer, RA; Giles, HF; Whitcomb, DR, "Structure and properties of cis-bis(dicyclohexylphosphine)dihalogeno-nickel(II) complexes", Journal of the Chemical Society, Dalton TransactionsDecember,, 1978(12), 1671-1677, Royal Society of Chemistry (RSC) [Gateway.cgi], [doi].
    (last updated on 2024/11/19)

    Abstract:
    Dicyclohexylphosphine and tetracyclohexyldiphosphane both react with anhydrous nickel(II) chloride and bromide to form the same type of complex in either case, namely cis-[NiX2{P(C6H11)2H}2] (X = Cl or Br). This has been confirmed in the solid state by X-ray diffraction and in solution by 1H and 31P n.m.r. spectroscopy. Other spectro-scopic data, as well as melting points, molecular weights, and elemental analyses, are also compatible with this conclusion. Evidence for a trans isomer of the bromide in solution is also observed. No evidence for the formation of a three-membered chelate ring in the reactions with the diphosphane could be detected. The 31P chemical shifts in CH2Cl2, are 36.4 (20 °C, 0.2 mol dm-3) and -46.1 and -30.5 p.p.m. (0 °C, 0.2 mol dm-3) for cis-[NiCl2{P(C6H11)2H}2], cis-[NiBr2{P(C6H11)2H}2], and trans-[NiBr2{P(C6H11)2H} 2] respectively, relative to 85% H3PO4. The complexes exhibit strong P-H coupling due to the secondary phosphine proton. X-Ray diffraction shows that cis-[NiCl2{P(C6H11)2H}2] crystallizes in the tetragonal space group /41/a (No. 88) with a = 20.69(1) and b = 25.15(2) Å, and Z = 16. The structure was solved, using Weissenberg methods and the heavy-atom technique from 1400 independent reflections using Cu-Kα radiation, to R′ 0.118. The nickel atom is 0.05 Å from the plane formed by the chlorine and phosphorus atoms. The average Ni-Cl distance IS 2.20(1) Å and the average Ni - P distance is 2.15(l) Å.