SYNTHESIS, MOLECULAR-STRUCTURE, AND VIBRATIONAL-SPECTRA OF CYCLO-BIS(MU-CARBONYL)DIPALLADIUM(I) FLUOROSULFATE, [C-PD2(MU-CO)2](SO3F)2

The synthesis, molecular structure, and complete vibrational spectrum of cyclo-bis(mu-carbonyl)dipalladium(I) fluorosulfate, [c-Pd2(mu-CO)2] (SO3F)2, are reported. The synthesis is achieved by reductive decomposition of Pd-(CO)2(SO3F)2 in fluorosulfuric acid, HSO3F; at 25-degrees-C, long orange-red needles form over a period of about 3 weeks. The compound is stable up to 157-degrees-C (the decomposition point). The molecular structure is solved by single-crystal X-ray diffraction. Crystals of [Pd2(mu-CO)2](SO3F)2 are monoclinic, C2/c; a = 11.495(1), b = 8.255(1), and c = 9.556(1) alpha; beta = 91.94(1)degrees; Z = 8. The structure is solved by the Patterson method and is refined by full-matrix least-squares procedures to R = 0.061 and R(w) = 0.075 for 2667 reflections with I greater-than-or-equal-to 3sigma(I). The structure reveals planar [Pd2(mu-CO)2]2+ cations formed by two nearly symmetrically CO-bridged palladium atoms, linked by bidentate-bridging fluorosulfate anions into a polymeric sheet. The vibrational spectrum using FT-IR and FT-Raman spectroscopy down to 50 cm-1 is interpreted in terms of D2h symmetry for the molecular cation, and 10 of the expected 12 fundamental vibrations are detected and assigned. The vibrational spectrum features the highest CO stretching frequency (nuBAR(CO)av = 2002 cm-1) so far reported for a bidentate-bridging CO ligand in metal-carbonyl chemistry.