Browsing by Author "Berry, David E."

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    Multimode coordination chemistry of [R2P(X)CHnP(Y)R'2](2-n)- ligands (X, Y = O, S, Se; n = 1, 2). Synthesis and phosphorus-31 NMR spectroscopy of platinum complexes
    (1992) Berry, David E.; Browning, Jane; Dixon, Keith R.; Hilts, Robert; Pidcock, Alan
    Reactions of the bis(phosphine chalcogenides) CH2|P(X)R2l|P(Y)R'2l (X, Y = O, S, Se) and their derived anions [CH|P-(X)R2)lP(Y)R'2l]" with chloroplatinum complexes PtCl42", [Pt2Cl4(PEt3)2], or [Pt2Cl2(PEt3)4]2+ result in a wide variety of coordination complexes. For example, when R = R' = Ph and X = Y = S, the following are all accessible in high yield: [PtCl(PEt3){CH2(P(S)Ph2)2-S^|]+, [PtCl(PEt3)iCH(P(S)Ph2)2-C,S|], [PtCl(PEt3)|CH(P(S)Ph2)2-S^|], [Pt(PEt3)2|CH2(P(S)-Ph2)2)-5^i]2+, [Pt(PEt3)2(CH(P(S)Ph2)2-C,S|]+, [PtCl2lCH2(P(S)Ph2)2-S^l], [Pt|CH2(P(S)Ph2)2-.S„S|2]2+, and [Pt(CH(P-(S)R2)2-C^|2]· A more limited range of complexes is also reported for X = Y = O, X = Y = Se, and X = O, Y = S. In general, the ligands exhibit at least five different coordination modes: (i) Bidentate X,Y coordination of neutral ligands; (ii) bidentate X,Y coordination of the anionic ligands; (iii) bidentate C,X coordination of the anions in a strained four-membered ring; (iv) monodentate C coordination of the anions; (v) complex C,S bridging mode involving a dianionic ligand and two metal centers. Interconversion reactions and characteristic 31P NMR spectroscopy are described for all of the coordination modes, including dynamic NMR studies of the C,X modes. These last modes all exhibit some degree of fluxional behavior, involving an exchange of coordinated and noncoordinated P=X groups in essentially a classic “bimolecular” substitution reaction, except that the incoming ligand is actually part of one of the existing ligands.
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    Platinum and palladium complexes of [R2PCH2P(Y)R′2] and [R2PCHP(Y)R′2]− ligands, Y = O,S, or Se: 13C, 31P, 77Se, and 195Pt nuclear magnetic resonance studies and the crystal and molecular structures of trans-[PtCl(PEt3){But2PCH2P(O)Me2}][ClO4] and trans-PtCl(PEt3){Ph2PCH2P(S)But2}|[ClO4]
    (1988) Berry, David E.; Browning, Jane; Dixon, Keith R.; Hilts, Robert
    Reactions of the bisphosphine monochalcogenides, [Ph2PCH2P(Y)R2], Y = O, S, or Se, R = Ph, Pri, or But, with the chloro-bridged dimers [M2Cl4(PR′3)2], M = Pd or Pt, R′ = Et or Bun, in the presence of either NaClO4or NaBF4yield perchlorate and fluoroborate salts of the complex cations cis- and trans-[PtCl(PR′3){Ph2PCH2P(Y)R2}]+. In many cases both cisand transisomers (defined by the relative orientation of the two M—P bonds) are obtained and the precise isomer distribution is a sensitive function of the substituents. Corresponding neutral complexes, cis- and trans-[PtCl(PR′3){Ph2PCHP(Y)R2}], can be synthesized either by deprotonation of the cations using NaH or by use of the salts Li[Ph2PCHP(Y)R2] in the initial bridge cleavage reactions. These and related complexes are characterized by complete 13C, 31P, 77Se, and 195Pt NMR studies and by two crystal structure determinations. The complexes I, trans-[PtCl(PEt3){But2PCH2P(O)Me2}][ClO4], and II, trans-[PtCl(PEt3){Ph2PCH2P(S)But2}][ClO4], crystallize in the monoclinic space group P21/c, respective cell dimensions: a = 15.579(2), b = 13.590(3), c = 13.578(1) Å;β= 105.96(1)°; and a = 14.002(4), b = 16.366(5), c = 15.524(5) Å; β = 106.01 (3)°. Complete X-ray diffraction studies show that both complexes contain closely square planar platinum centres with the R2PCH2P(Y)R′2ligands coordinated via phosphorus and the Y atom so as to form five-membered chelate rings. The molecular dimensions suggest that the bond to sulphur is stronger than that to oxygen and exerts a larger transinfluence.