Synthetic and structural studies of bismuth alkoxide complexes

[摘要] The salt elimination reaction between Ph3BiBr 2 and a metal alkoxide MIOR (MI = Ag, Na; R = C6F5, C6Cl5, 2,6-C 6H3F2, OTf) yields the compounds Ph3Bi(OR)Br and Ph3Bi(OR)2 depending upon stoichiometry. The alcoholysis reaction between BiPh5 and HOR results in the formation of Ph 4Bi(OR). The structure in the solid state and in solution of those bismuth(V) alkoxide compounds are trigonal bipyramidal with phenyl groups occupying the equatorial positions. For compounds Ph3Bi(OR)Br an equilibrium in solution was observed: Ph3Bi(OR)2 + Ph3BiBr 2 &rlhar2; 2 Ph3BiBr(OR). The equilibrium constants for R = C 6F5, C6Cl5 have been determined. Mixing the bismuth(III) alkoxide [Bi(OC6F5) 3]2 with NaOC6F5 leads to the formation of mixed metal alkoxides, [NaBi(OC6F5)4THF] and Na4Bi2(O)(OC6F5)8. Compound NaBi4(O)2(OC6F5) 9 can be synthesized from BiCl3 and NaOC6F 5 in THF. These alkoxide compounds show interesting dynamics in solution which were investigated with variable temperature fluorine NMR spectroscopy. [NaBi(OC6F5)4THF] exists as a polymeric chain in the solid state. Dissolution of the bismuth(III) alkoxide, (Bi(OC6F5) 3]2 in organic solvents promotes rearrangement reactions of the bismuth alkoxide, involving ether elimination or microhydrolysis. The higher nuclearity bismuth oxo alkoxides Bi4(mu4-O)(mu 2-OC6F5)6{mu3- OBi(OC 6F5)3}2, Bi8(mu4 -O)2(mu3-O)2(OC6F 5)16 and Bi6(mu3-O)4(mu 3-OC6F5){mu3-OBi(OC6F 5)4}3 were isolated and structurally characterized. Common to all three bismuth oxo alkoxides is the presence of mu4-OBi 4 and mu3-OBi3 units. Variable temperature NMR studies suggest that the structure in solution resembles the structure in the solid state.

[发布机构] Rice University