CHALCOGENIDE SUBSTITUTION-REACTIONS

The feasibility of preparing tellurometalates from selenometalates has been demonstrated by the preparation of the compounds [PPh4]4[Ni4Te4(Te2)2(Te3)4] and [PPh4]4[Pt4Te4(Te3)6] from the reactions in DMF of TePEt3 with [PPh4]2[Ni(Se4)2] and [PPh4]2[Pt(Se4)3], respectively. The NEt4+ salt of the [Pt4Te4(Te3)6]4- ion could also be isolated from the reaction of Pt(xan)2 with Li2Te and Te in DMF. The anion [Ni4Te4(Te2)2(Te3)4]4- has a Ni4Te4 cubane core, with pairs of Te-2(2-) chains bridging Ni(IV) atoms on opposite faces of the core and four Te-3(2-)chains bridging the Ni(IV) atoms on the remaining cubane faces. The anion [Pt4Te4(Te3)6]4-possesses a Pt4Te4 cubane core and has six Te-3(2-)chains bridging, Pt(IV) atoms on the cubane faces. In the cubane anions each metal atom is in a distorted octahedral environment, being coordinated by three Te atoms in the cubane framework and by three Te atoms in chains that bridge to the other three metal atoms. Unit cell data(-163-degrees-C): [PPh4]4[Ni4Te4(Te2)2(Te3)4], space group D2d(8)-P4n2BAR, a = 18.925(3) angstrom, c = 17.155(3) angstrom, V = 6144(2)angstrom3, Z = 2; [PPh4]4[Pt2Te4(Te3)6], space group C-3v(6)-R3c, a = 27.024(3) angstrom, alpha = 59.91(2)-degrees, V = 13954(3)angstrom3, Z = 4; [NEt4]4[Pt4Te4(Te3)6].2DMF, space group C-2h(5)-P2(1)/c, a = 15.685(3) angstrom, b = 40.103(8) angstrom, c = 15.330(3) angstrom, beta = 119.10(3)-degrees, V = 8426(3) angstrom3, Z = 4.