Synthesis and Characterization of HN(SP<i>ⁱ</i>Pr₂)(SePPh₂) and [Te{N(SP<i>ⁱ</i>Pr₂)(SePPh₂)}₂]

The compound HN(SPiPr2)(SePPh2) has been synthesized from the reaction of Ph2P(Se)NH2 with iPr2P(S)Cl in the presence of NaH in THF. HN(SPiPr2)(SePPh2) crystallizes with eight formula units in space group Pbca of the orthorhombic system in a cell of dimensions at −120 °C of a = 9.9560(6) Å, b = 17.9053(10) Å, c = 22.4156(13) Å, and V = 3995.9(4) Å3. The square-planar Te(II) complex [Te{N(SPiPr2)(SePPh2)}2] has been isolated from the reaction of Te(tu)4Cl2·2H2O (tu = thiourea) with the anion [N(SPiPr2)(SePPh2)]-, generated in situ from HN(SPiPr2)(SePPh2) in the presence of KOtBu. [Te{N(SPiPr2)(SePPh2)}2] is dimorphic, crystallizing with one formula unit in space group P1̄ of the triclinic system in a cell of dimensions at −120 °C of a = 9.8476(9) Å, b = 10.3296(9) Å, c = 11.3429(10) Å, α = 101.903(1)°, β = 115.471(1)°, γ = 92.281(2)°, and V = 1008.4(2) Å3 and also crystallizing with two formula units in space group P21/n of the monoclinic system in a cell of dimensions at −120 °C of a = 8.7931(5) Å, b = 17.1830(10) Å, c = 14,1026(9) Å, β = 104.696(1)°, and V = 2061.1(2) Å3. In each instance, the [Te{N(SPiPr2)(SePPh2)}2] molecule possesses a center of symmetry, comprising a Te center liganded in a trans manner by two bidentate N(SPiPr2)(SePPh2) groups. However, the 31P, 77Se, and 125Te NMR spectra of [Te{N(SPiPr2)(SePPh2)}2] show two sets of resonances at 25 °C. The 31P VT NMR spectra show two sets of resonances between −50 and +50 °C that coalesce between 80 and 100 °C, consistent with the presence of the cis as well as the trans isomer in solution.