Synthesis and characterization of HN(SPⁱPR ₂)(SePPh₂) and [Te{N(SPⁱPr ₂)(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(SP ⁱPr₂)(SE)PPh₂) 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) ų. 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(SPⁱPr ₂)(SePPh₂)]^-, generated in situ from HN(SP ⁱPr₂)(SePPh₂) in the presence of KO ⁱBu. [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) ų 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) ų. 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(SPⁱPr ₂)(SePPh₂) groups. However, the ³¹P, ⁷⁷Se, and ¹²⁵Te NMR spectra of [Te{N(SPⁱPr ₂)(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.