EFFECT OF CHARGE ON STRUCTURE - STEPWISE PROTONATION OF [EFE(3)(CO)(9)](2-) (E=SE, TE) AND ISOLATION OF THE NOVEL MIXED-METAL CLUSTER [TEFE3(CO)(9)(MU-CUCL)](2-)

The clusters [EFe(3)(CO)(9)](2-) (E = Se, Te) were protonated stepwise with triflic acid to produce both the monohydride clusters [HEFe(3)(CO)(9)](-) and the dihyride clusters H(2)EFe(3)(CO)(9). The effect of the presence of the hydrides as well as that of the overall cluster charge on the structure was probed both spectroscopically and crystallographically. The C-13 NMR shifts and the IR stretching frequencies of the carbonyl ligands was found to be correlated with the cluster charge in a linear fashion, [PPN][HSeFe3(CO)(9)] crystallizes in the monoclinic space group P2(1)/c (No. 14) with a = 9.359(2) Angstrom, b = 29.648(6) Angstrom, c = 16.057(3) Angstrom, beta = 101.23(3)degrees and V = 4370.1(15) Angstrom(3). The isostructural telluride [PPN][HTeFe3(CO)(9)] also crystallizes in the monclinic space group P2(1)/n (No. 14) with a = 8.925(2) Angstrom, b = 13.985(3) Angstrom, c = 35.798(7) Angstrom, beta = 97.13(3)degrees, and V = 4433.6(16) Angstrom(3). H2SeFe3(CO)(9) crystallizes in the monoclinic space group P2(1)/n with a = 8.862(2) Angstrom, b = 11.503(2) Angstrom, 14.936(3) Angstrom, beta = 103.28(3)degrees, and V = 1481.9(5) Angstrom(3). The tellurium analog H2TeFe3(CO)(9) crystallizes in the centrosymmetric triclinic space group P ($) over bar 1 (No. 2) with a = 7.8814(4) Angstrom, b = 8.9414(7) Angstrom c = 11.8243(4), a = 82.318(5)degrees, beta = 77.664(4)degrees, gamma = 69.303(4)degrees, and V = 759.95(8) Angstrom(3). The reaction of [TeFe3(CO)(9)](2-) with either CuCL or Et(3)PCuCl produced the unusual cluster [TeFe3(CO)(9)(mu CuCl)](2-). A crystallographic study of the [PPN]+ salt confirmed the presence of the chloride ligand. [PPN]2[TeFe3(CO)(9)(mu-CUCl)], which crystallizes in the orthorhombic space group Pbca (No. 61) with a = 24.274(5) Angstrom, b = 21.634(4) Angstrom, c = 30.363(6) Angstrom, and V = 15944.9(54) Angstrom(3), is therefore the first example of a mixed iron-copper cluster which retains a halide ligand bound to copper.