Organometallic supramolecular mixed-valence cobalt(I)/cobalt(II) aquo complexes stabilized with the water-soluble phosphine ligand p-TPPTP (p-triphenylphosphine triphosphonic acid)

Reaction of the water-soluble phosphine phosphonic acid p-TPPTP(H)(6) (p-triphenylphosphine triphosphonic acid) with Co-2(CO)(8) under biphasic conditions results in the formation of Co-6(CO)(3)(p-TPPTP)(2)(H2O)(24)center dot 24H(2)O (2) or Co-4(CO)(3)(p-TPPTP)(2)(H2O)(24)center dot 24H(2)O (3) depending on the pH of the solution. These supramolecular organometallic Co(I)/Co(II) complexes contain either six (2) or four (3) crystallographically distinct cobalt ions. The cation [Co(CO)(3)(p-TPPTP)(2)](+) from 2 was reacted with titanium tetraisopropoxide via a sol-gel method to give a titania-supported Co(I) olefin hydroformylation catalyst, which was characterized using solid-state P-31 NMR, IR, and XPS.