Structural and spectroscopic trends in mononuclear arylchalcogenolato-palladium(II) and -platinum(II) complexes:: Crystal structures of [M(TeAr)2(dppe)] {M = palladium, platinum;: Ar = phenyl, 2-thienyl;: dppe=1,2-bis(diphenylphosphino)ethane}

A series of mononuclear [M(EAr)(2)(dppe)] [M = Pd, Pt; E = Se, Te; Ar = phenyl, 2-thienyl; dppe = 1,2-bis(diphenylphosphino)ethane] complexes has been prepared in good yields by the reactions of [MCl2(dppe)] and corresponding ArE- with a special emphasis on the aryltellurolatopalladium and -platinum complexes for which the existing structural information is virtually non-existent. The complexes have crystallized in five isomorphic groups: (1) [Pd(SePh)(2)(dppe)] and [Pt(SePh)(2)(dppe)], (2) [Pd(TePh)(2)(dppe)] and [Pt(TePh)(2)(dppe)], (3) [Pd(SeTh)(2)(dppe)], (4) [Pt(SeTh)(2)(dppe)] and [Pd(TeTh)(2)(dppe)], and (5) [Pt(TePh)(2)(dppe)]. In addition, solvated [Pd(TePh)(2)(dppe)] center dot CH3OH and [Pd(TeTh)(2)(dppe)] center dot 1/2CH(2)Cl(2) could be isolated and structurally characterized. The metal atom in each complex exhibits an approximate square-planar coordination. The Pd-Se, Pt-Se, Pd Te, and Pt-Te bonds span a range of 2.4350(7)2.4828(7) angstrom, 2.442(l)-2.511 (1) angstrom, 2.5871(7)-2.6704(8) angstrom, and 2.6053(6)-2.6594(9) angstrom, respectively, and the respective Pd-P and Pt-P bond distances are 2.265(2)-2.295(2) angstrom and 2.247(2)-2.270(2) angstrom. The orientation of the arylchalcogenolato ligands with respect to the M(E-2)(P-2) plane has been found to depend on the E-M-E bond angle. The NMR spectroscopic information indicates the formation of only cis-[M(EAr)(2)(dppe)] complexes in solution. The trends in the P-31, Se-77, Te-125, and Pt-195 chemical shifts expectedly depend on the nature of metal, chalcogen, and aryl group. Each trend can be considered independently of other factors. The Se-77 or Te-125 resonances appear as second-order multiplets in case of palladium and platinum complexes, respectively. Spectral simulation has yielded all relevant coupling constants. (c) 2007 Elsevier B.V. All rights reserved.