THE PREPARATION AND CRYSTAL STRUCTURE OF DIMOLYBDENUM TETRAFORMATE; PHOTOELECTRON SPECTRA OF THIS AND SEVERAL OTHER DIMOLYBDENUM TETRACARBOXYLATES

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Abstract
The compound Mo2 (O2CH)4 is described in detail for the first time and its crystal structure is reported. Crystallographic parameters are: Space group: P21 21 21; a = 12.288(4)Å; b = 12.930(5)Å; c = 5.500(1)Å, and Z = 4. Using 952 reflections for which I < 3 [sgrave](I) the structure has been solved and refined to R 1 = 0.063 and R 2 = 0.071. The molecule has virtual symmetry D4 h and all comparable dimensions are virtually identical to those of Mo2 (O2 CCH3)4; for example, the Mo—Mo distance is 2.091(2)Å. The Raman spectrum has a band at 403 cm−1 due mainly to Mo—Mo stretching. The photoelectron spectra of the Mo2 (O2CR)4 compounds with R = H, CH3 and CF3 are reported. The spectra are qualitatively similar and exhibit trends in accord with the relative electronegativities of the R groups, in harmony with the results of an earlier study which also included the formate and acetate.