APPLICATION OF THE HYDRO(SOLVENTO)THERMAL TECHNIQUE TO THE SYNTHESIS OF METAL-CARBONYL CHALCOGENIDE CLUSTERS .2. SYNTHESIS AND X-RAY STRUCTURES OF [(FE4TE4(CO)10)2(TE2)]2- AND [(FE2SE(CO)6)2(SE2)]2-

The hydrothermal reaction of Fe(CO)5 with Na2Te2 in the presence of Ph4PCl at 110-degrees-C forms (Ph4P)2[{Fe4Te4(CO)10}2(Te2)] (I) While the reaction of Fe(CO)5 with Na2Se2 in superheated methanol at 80-degrees-C results in (Ph4P)2[{Fe2Se(CO)612(Se2)] (II). The structures of (I) and (II) were determined by X-ray single-crystal analysis. (1) crystallizes in the space group P1BAR, and (II) in the space group P2(1)/n. The cell parameters are a = 14.930(4) angstrom, b = 24.070(3) angstrom, c = 13.045(2) angstrom, a = 93.19(1)-degrees, beta = 11 3.36(1)-degrees, gamma = 76.61(2)-degrees, V = 4183(3) angstrom3, and Z = 2 at 23-degrees-C for (I) and a = 10.561(6) angstrom, b = 14.021(5) angstrom, c = 20.46(1) angstrom, beta = 91.89(4)-degrees, V = 3028(2) angstrom3, and Z = 4 at -100-degrees-C for (II). The [{Fe4Te4(CO)10}2(Te2)]2- anion in (I) forms a ditelluride, Te-2(2-), bridged double cubane-like structure with eight iron atoms in two Fe4Te4 cubes being octahedrally-coordinated by bridging tellurium ligands and terminal CO groups. The [{Fe2Se(CO)6}2(Se2)]2- molecule in (II) adopts a double ''butterfly'' conformation caused by an intramolecular Se-Se linkage between two Fe2Se2(CO)6 units. All iron atoms in this structure have a distorted octahedral geometry achieved by selenium ligands, CO groups, and a Fe-Fe single bond. The average Fe-Te bond distance is 2.619(4) angstrom, and Fe-Se = 2.386(17) angstrom.