148352-72-1Relevant academic research and scientific papers
Intramolecular redox and methyl for chloride exchange processes at platinum(II) metal centers bridged by the short bite ligand 2-(diphenylphosphino)pyridme
Arena, Carmela Grazia,Bruno, Giuseppe,De Munno, Giovanni,Rotondo, Enrico,Drommi, Dario,Faraone, Felice
, p. 1601 - 1606 (2008/10/08)
The reaction of cis-[Pt(DMSO)2Cl2] (DMSO = dimethyl sulfoxide) with 2-(diphenylphosphine)pyridine (Ph2PPy) leads, as major product, to the square planar platinum(II) species cis-[Pt(DMSO)(Ph2PPy)Cl2] (1), in which the Ph2PPy is η1-bonded through the phosphorus atom to metal center. The NMR spectra, in chloroform solution, indicates that 1 is in equilibrium with a species containing the Ph2PPy as a chelating ligand, namely [Pt(Ph2PPy)Cl2]. The binuclear compounds [(CH3)ClPt(μ-Cl)(μ-Ph2PPy)Pt(CH 3)(DMSO)]DMSO (2) and [Pt2(μ-Ph2PPy)2Cl2] DMSO (3) have been isolated from the reaction of 1 with an equimolar amount of cis-[Pt(DMSO)2(CH3)2]. Compounds 2 and 3 have been structurally characterized by an X-ray diffraction study. A plausible reaction scheme which accounts for the formation of both 2 and the platinum(I)-platinum(I) complex 3, by intramolecular processes, is discussed; the first step of the reaction involves the formation of the binuclear species [(DMSO)Cl2Pt(μ-Ph2PPy)Pt(CH3) 2(DMSO)] (4) by nucleophilic attack of the pyridine nitrogen atom of 1 on the platinum(II) center of the coordinately unsaturated species [Pt(DMSO) (CH3)2]. Compound 2 crystallizes in the monoclinic space group C2/c with a = 35.105(4) A?, b = 11.578(2) A?, c = 14.572(2) A?, β = 111.81(2)°, V = 5499(1) A?3 Z = 8. On the basis of 4131 independent observations and 309 parameters, the structure was refined to R = 0.035 and Rw = 0.041. Each platinum atom is in an nearly square planar environment and is surrounded by the Ph2PPy and the chloride atom of the bridging ligands. The coordination around Pt(1) is completed by the nitrogen atom from the Ph2PPy bridging ligand, the sulfur atom of DMSO, and one methyl group; the coordination around the Pt(2) involves, beyond the chloride bridged atom and the phosphorus of Ph2PPy, one methyl group and the terminal chloride. The P(1)Pt(2)Pt(1)N(1) torsion angle of 35.2(2)° is indicative of a rather strong steric hindrance in the complex. Compound 3 crystallizes in the monoclinic space group C2/c with a = 30.296(4) A?, b = 17.805(3) A?, c = 12.992(2) A?, β = 98.14(1)°, V = 6937(2) A?3, and Z = 8. On the basis of 5022 independent observations and 422 parameters, the structure was refined to R = 0.032 and Rw = 0.035. The platinum atoms are in a nearly square planar environment, the angles at platinum centers between mutually cis ligands being in the range 79.42(5)-99.11(7)°. The platinum centers are joined by a short metal-metal bond (2.5853(6) A?). The metal coordination planes are twisted about the Pt-Pt vector giving a dihedral angle of 35.6(1)°. The Pt(1)-Cl(1) and Pt(2)-Cl(2) bond distances of 2.397(2) and 2.420(2) A? reflect the high trans influence of the platinum-platinum bond.
