The compound HN((SPPr2)-Pr-i)(SePPh2) has been synthesized from the reaction of Ph2P(Se)NH2 with (Pr2P)-Pr-i(S)Cl in the presence of NaH in THF. HN((SPPr2)-Pr-i)(SePPh2) crystallizes with eight formula units in space group Pbca of the orthorhombic system in a cell of dimensions at -120 degreesC of a = 9.9560(6) Angstrom, b = 17.9053(10) Angstrom, c = 22.4156(13) Angstrom, and V = 3995.9(4) Angstrom(3). The square-planar Te(II) complex [Te{N((SPPr2)-Pr-i)(SePPh2)}(2)] has been isolated from the reaction of Te(tu)(4)Cl-2.2H(2)O (tu = thiourea) with the anion [N((SPPr2)-Pr-i)(SePPh2)](-), generated in situ from HN(SPi Pr-2)(SePPh2) in the presence of (KOBu)-Bu-t. [Te{N((SPPr2)-Pr-i)(SePPh2)}(2)] is dimorphic, crystallizing with one formula unit in space group P (1) over bar of the triclinic system in a cell of dimensions at -120 degreesC of a = 9.8476(9) Angstrom, b = 10.3296(9) Angstrom, c = 11.3429(10) Angstrom, alpha = 101.903(1)degrees, beta = 115.471(1)degrees, gamma = 92.281(2)degrees, and V = 1008.4(2) Angstrom(3) and also crystallizing with two formula units in space group P2(1)/n of the monoclinic system in a cell of dimensions at -120 degreesC of a = 8.7931(5) Angstrom, b = 17.1830(10) Angstrom, c = 14,1026(9) Angstrom, beta = 104.696(1)degrees, and V = 2061.1(2) Angstrom(3). In each instance, the [Te{N((SPPr2)-Pr-i)(SePPh2)}(2)] molecule possesses a center of symmetry, comprising a Te center liganded in a trans manner by two bidentate N((SPPr2)-Pr-i)(SePPh2) groups, However, the P-31, Se-77, and Te-125 NMR spectra of [Te{N((SPPr2)-Pr-i)(SePPh2)}(2)] show two sets of resonances at 25 degreesC. The P-31 VT NMR spectra show two sets of resonances between -50 and +50 degreesC that coalesce between 80 and 100 degreesC, consistent with the presence of the cis as well as the trans isomer in solution.