NEW DIALKYL TELLURIDES - SYNTHESIS AND LIGAND PROPERTIES OF TE((CH2)NSI(CH3)3)2 (N=1,3) AND CRYSTAL-STRUCTURE OF TRANS-PD(SCN)2[TE(CH2CH2CH2SI(CH3)3)2]2

The dialkyl tellurides Te((CH2)nSi(CH3)3)2 (n=1, 3) have been prepared by alkylation of Na2Te with the corresponding alkyl chlorides. Coordination complexes of these two new, somewhat air-sensitive, liquid ligands with palladium chloride and thiocyanate (i. e., PdX2[Te((CH2)„Si(CH3)j)2]2) have been prepared. The complexes have a trans geometry on the basis of their infrared and Raman spectra. Infrared and 1H NMR spectra support Pd-SCN bonding modes for the thiocyanate complexes in the solids and CHC13 solutions. A single-crystal X-ray structure determination has confirmed the proposed structure of trnas-Pd (SCN)2[Te(CH2CH2CH2Si(CH3)3)2]2. The square-planar complex contains two sulfur-bonded thiocyanates in a trans arrangement. The configuration at tellurium is pyramidal with a stereochemically active lone pair of electrons at the fourth corner of a tetrahedron. There is probably some γ bonding between sulfur and palladium but not between tellurium and palladium. The crystals are monoclinic, P21/c with [formula omitted] The structure was solved by the heavy-atom method and refined by block-diagonal least squares to R=0.082 for 3173 observed reflections. The thiocyanate complexes retain the sulfur-bonding mode in CHC13 solution, but formation of some cis isomers is suggested by their infrared spectra. © 1979, American Chemical Society. All rights reserved.