A Re(CO)5 fragment bonded to a polyhedral oligomeric hydroxysilsesquioxane as a model which gives further evidence to the existence of an unexpected Re(CO)5 surface species

Reaction of Re(CO)5O3SCF3 with (c-C6H11)7Si8O12O-Li+ at 273 K under a CO atmosphere affords the [Re(CO)5OR] (R = (c-C6H11)7Si8O12) derivative (1). 1 is the first example of a rhenium pentacarbonyl bearing an OR ligand (R = alkyl, aryl, or silyl) stable enough to be characterized, and it represents also the first molecular model of the surface [Re(CO)5OSi≡] species formed by reductive carbonylation of silica-supported [Re(CO)3OH]4. At room temperature, 1 loses one carbonyl ligand and dimerizes to afford Re(CO)4[(μ-O)O12Si8(c-C6H11)7]2 (2), which has been characterized by X-ray diffraction and is the first reported example of a rhenium tetracarbonyl μ-oxo-bridged dimer of the type [Re(CO)4(μ-OR)]2. Copyright © 2006 American Chemical Society.