155640-79-2Relevant articles and documents
Preparation, structures, and fluxional behavior of organolithium derivatives of a 1,5-diphosphadithiatetrazocine and their complexes with platinum(II) and palladium(II)
Chivers, Tristram,Edwards, Mark,Hilts, Robert W.,Parvez, Masood,Vollmerhaus, Rainer
, p. 1440 - 1447 (2008/10/08)
The reaction of the diphosphadithiatetrazocine 1,5-Ph4P2N4S2 with organolithium reagents RLi (R = Me, But, Ph, CH2PPh2) in THF generates Li[Ph4P2N4S2R]. An X-ray structural determination shows that the phenyl derivative is a dimer [Li(Ph4P2N4S2Ph)·THF] 2 with a step-shaped structure. The phenyl group is attached to sulfur, and each lithium atom is coordinated, almost symmetrically, to two nitrogen atoms on the opposite side of the P2N4S2 ring and to one nitrogen atom of the other P2N4S2 ring. A single THF molecule completes the coordination sphere of the lithium atoms. The crystals of [Li(Ph4P2N4S2Ph)·THF] 2 are triclinic, space group P1, with a = 13.189(10) A?, b = 13.355(8) A?, c = 11.760(5) A?, α = 90.67(4)°, β = 114.15(4)°, γ = 114.05(5)°, V = 1683(2) A?3, and Z = 2. The final R and Rw values were 0.072 and 0.060, respectively. 7Li and 31P NMR investigations of [Li(Ph4P2N4S2R)·THF] 2 (R = Me, But, Ph, CH2PPh2), as a function of temperature and concentration in THF, show that these dimers are fluxional and provide evidence for a second species, which is tentatively identified as a symmetrical dimer with two molecules of THF coordinated to each lithium atom. The treatment of Li[Ph4P2N4S2Me] with iodomethane gives the S,S′-dimethyl derivative 1,5-Ph4P2N4S2Me2 and the reaction of Li[Ph4P2N4S2R] with MCl2(PEt3)2 (M = Pt, Pd) produces metal complexes of the type trans-MCl(PEt3)2(Ph4P2N 4S2R) (M = Pt, R = Me, But, Ph, CH2PPh2; M = Pd, R = Me) in which the metal and the R group are attached to opposite sulfur atoms. A variable-temperature 31P NMR study of these metal complexes reveals an intramolecular dynamic exchange of the inequivalent PEt3 groups, which is attributed to rotation about the metal-sulfur bond. The activation energy for this exchange is ca. 45 kJ mol-1 and is essentially independent of the nature of the R group attached to the other sulfur atom or the identity of the metal. The reaction of Li[Ph4P2N4S2Me] with cis-PtCl2(PPh3)2 in THF at 65 °C produces Pt(PPh3)2(η2-Ph4P 2N4S2-S,S′) and Pt(PPh3)(η1-THF-O)(Ph4P2N 4S2) in an approximately 2:3 molar ratio.
