Synthesis and characterization of Na5[Co(CO)3(P{(CH2)nC6H4-P-SO3}3)2], n = 1, 2, 3, and 6. Novel zwitterion

The electron donating water soluble phosphines, P{(CH₂)nC₆H₄-p-SO₃Na}₃,n = 1, 2, 3 and 6, react rapidly with Co₂(CO)₈ under two phase reaction conditions to yield the disproportionation products, [Co(CO)₃(P{(CH₂)nC₆H₄-p-SO₃Na₃}₂] [Co(CO)₄]. Selective precipitation yields the formally zwitterionic complex anions as the sodium salt, [Co(CO)₃(P{(CH₂)nC₆H₄-p-SO₃} ₃)₂]⁵⁻. The anions can be used as precursors to water soluble cobalt hydroformylation catalysts under two phase and supported aqueous phase conditions. The tendency to form alcohol products is low with these complexes. The behavior of the catalysts is consistent with an active species that remains water soluble during the reaction and is not leached into the nonaqueous phase.