Syntheses and X-ray structures of the bridging and chelating isomers of Os-3(CO)(10)(dmpe)

摘要

The substitution chemistry of the activated clusters Os-3(CO)(10)(MeCN)(2) (1) and Os-3(CO)(10)(1,5-cod) (2) has been investigated with the bidentate ligand 1,2-bis(dimethylphosphino)ethane (dmpe). Both starting clusters react rapidly with dmpe at room temperature to give the corresponding substitution product Os-3(CO)(10)(dmpe) (3), whose isomeric composition is shown to depend on the nature of the starting cluster. Whereas the bridged cluster 1,2-Os-3(CO)(10)(dmpe) (3b) was formed almost exclusively upon reaction with Os-3(CO)(10)(MeCN)(2), a near statistical mixture of bridging (3b) and chelating (3c) isomers of Os-3(CO)(10)(dmpe) was found in the reaction employing Os-3(CO)(10)(1,5-cod). Both dmpe isomers have been characterized in solution by 3iP NMR spectroscopy and their solid-state structures established by X-ray crystallography. The bridged cluster 1,2-Os-3(CO)(10)(dmpe) crystallizes in the monoclinic space group P2(1), a = 9.867(2) angstrom, b = 17.081(3) angstrom, c = 14.198(2) angstrom, beta = 95.902(3)degrees, V = 2380.4(6) angstrom(3), Z = 4, and d(calc) = 2.793 Mg/m(3); R = 0.0435, R-w = 0.0466 for 3519 reflections with I > 2 sigma(I). The chelated cluster 1,1-Os-3(CO)(10)(dmpe) crystallizes in the orthorhombic space group C222(1), a = 8.329(3) angstrom, b = 19.028(6) angstrom, c = 15.008(5) angstrom, V = 2379(1) angstrom(3), Z = 4, and d(calc) = 2.795 Mg/m(3); R = 0.0390, R-w = 0.0718 for 2360 reflections with I > 2 sigma(I).