- Reaction of Pt3(CO)3(P-t-Bu2Ph)3 and HCI. The x-ray structure of Pt2Cl2(CO)2(P-t-Bu2Ph)2
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The reaction of Pt3(CO)3(P-t-Bu2Ph)3 (1) with 3 equiv of HCl at -50°C results in immediate formation of PtHCl(CO)(P-t-Bu2Ph) (2) in which the hydride ligand is assigned to the position trans to the CO ligand. Complex 2 isomerizes rapidly at higher temperatures to give a second complex, PtHCl(CO)(P-t-Bu2Ph) (3), with the hydride ligand trans to the chloride ligand. Complex 3 slowly converts to a dinuclear Pt(I) complex shown by X-ray crystallography to be Pt2Cl2(CO)2(P-t-Bu2Ph)2 (4). Complex 4 crystallizes in the monoclinic space group P21/c with Z = 4 in a unit cell of dimensions a = 15.418 (1) A?, b = 14.751 (1) A?, c = 16.051 (2) A?, and β = 108.61 (1)°. The structure was refined by using 4065 independent reflections with 203 variables to R1 = 0.046 and R2 = 0.053. 4 contains an unsupported Pt-Pt bond (2.628 (1) A?), and the phosphine ligands are located trans to this bond. The Pt atom coordination spheres are essentially square-planar with a dihedral angle of 109.9° between the two planes. The rotational energy of the Pt-Pt bond and the relative stability of 4 and a hypothetical Cl-bridged isomer are examined by using EHMO calculations. 4 also can be prepared by reacting 1.5 equiv of Cl2 with 1 while reaction of 1 or 4 with excess Cl2 gives Pt(Cl)2(CO)(P-t-Bu2Ph) (7). Addition of excess NaBH4 to a solution of 3 regenerates 1, and reaction of 3 with AgPF6 gives [(Pt3(μ-CO)3(P-t-Bu2Ph)3) 2Ag] [PF6] (6). Complex 6 has been spectroscopically characterized as a Ag cation sandwiched between two units of 1. 6 is also the product of the reaction of 1 and AgPF6.
- Couture, Christiane,Farrar, David H.,Fisher, Duncan S.,Gukathasan, Ravi R.
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p. 532 - 536
(2008/10/08)
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