SYNTHESIS AND CHARACTERIZATION OF N,N-DIETHYL, PYRROLIDYL, AND PIPERIDYL MONOTHIOCARBAMATE DERIVATIVES OF DIMETHYLTELLURIUM(IV) - CRYSTAL-STRUCTURES OF ME(2)TE[SCONET(2)](2), ME(2)TECL[SCONET(2)], ME(2)TEBR[SCONET(2)], AND ME(2)TEI[SCONET(2)]

The dimethylbis(monothiocarbamato)tellurium(IV) compounds Me(2)Te[SCONR(2)](2), where NR(2) = NEt(2), N(CH2)(3)-CH2, and N(CH2)(4)CH2, and the halodimethyl(N,N-diethyl and pyrrolidyl monothiocarbamato)tellurium(IV) compounds Me(2)TeX[SCONR(2)], where X = Cl, Br, and I and NR(2) = NEt(2) or N(CH2)(3)CH2, have been prepared, with yields of 80% or better, by the reaction of the sodium salts of the monothiocarbamic acids, in excess or in equimolar amounts, with dimethyltellurium dihalide. The compounds were characterized by elemental analysis and H-1, C-13, and Te-125 NMR, infrared, and Raman spectroscopy. The crystal structures of Me(2)Te[SCONEt(2)](2), Me(2)TeCl[SCONEt(2)], Me(2)TeBr[SCONEt(2)], and Me(2)TeI[SCONEt(2)] were determined. Me(2)Te[SCONEt(2)](2) (1), which crystallizes as monoclinic in space group P2(1)/n (No. 14), has the cell parameters a = 11.184(2) Angstrom, b = 10.036(2) Angstrom, c = 16.531(2) Angstrom, beta = 94.08(1)degrees, V = 2424(1) Angstrom(3), Z = 4, R = 0.0337, and RW(=) 0.0270. Me(2)TeCl[SCONEt(2)] (4), which crystallizes as monoclinic in space group P2(1)/c (No. 14), has the cell parameters a = 10.539(2) Angstrom, b = 10.864(2) Angstrom, c = 11.511(2) Angstrom, beta = 112.23(1)degrees, V = 1220.0(4) Angstrom(3), Z = 4, R = 0.0319, and R(W) = 0.0289. Me(2)TeBr[SCONEt(2)] (5), which also crystallizes as monoclinic in space group P2(1)/c (No. 14), has the cell parameters 10.533(4) Angstrom, b = 10.965(2) Angstrom, c = 11.814(4) Angstrom, beta = 113.11(2)degrees, V = 1254.9(7) Angstrom(3), Z = 4, R = 0.0528, and R(W) = 0.0462. Me(2)TeI[SCONEt(2)] (6), which also crystallizes as monoclinic in space group P2(1)/c (No. 14), has the cell parameters a = 10.702(2) Angstrom, b = 11.241(1) Angstrom, c = 12.280(3) Angstrom, beta = 114.51(2)degrees, V = 1344.2(5) Angstrom(3), Z = 4, R = 0.0430, and R(W) = 0.0343. The immediate environment about tellurium in 1 and 4-6 can be described as that of a sawhorse structure in which the lone pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. The two methyl groups occupy the other equatorial positions with the sulfur atoms of the monothiocarbamate groups occupying both axial positions in the case of 1. In 4-6, the halogen atom occupies one of the axial positions. The S-Te-S angle in 1 is 168.35(5)degrees, and the S-Te-X angles range-from 171.34(8) to 171.62(8)degrees. The orientation of the monothiocarbamates is such as to suggest secondary intramolecular Te-O interactions, and if the oxygen atoms are considered as part of a coordination sphere, then the six atoms around telIurium in 1 have a distorted pentagonal pyramidal arrangement. The Te-X bond lengths are considerably longer than found in the parent Me(2)TeX(2) species.