Ferrous Carbonyl Dithiolates as Precursors to FeFe,FeCo, and FeMn Carbonyl Dithiolates.

Reportedare complexes of the formula Fe(dithiolate)(CO)2(diphos)and their use to prepare homo- and heterobimetallic dithiolatoderivatives. The starting iron dithiolates were prepared by a one-potreaction of FeCl2and CO with chelating diphosphines anddithiolates, where dithiolate = S2(CH2)22–(edt2–), S2(CH2)32–(pdt2–), S2(CH2)2(C(CH3)2)2–(Me2pdt2–) and diphos = cis-C2H2(PPh2)2(dppv), C2H4(PPh2)2(dppe), C6H4(PPh2)2(dppbz), C2H4[P(C6H11)2]2(dcpe). The incorporation of 57Fe into such building block complexes commenced with theconversion of 57Fe into 57Fe2I4(iPrOH)4, which thenwas treated with K2pdt, CO, and dppe to give 57Fe(pdt)(CO)2(dppe). NMR and IR analyses show that thesecomplexes exist as mixtures of all-cis and trans-CO isomers, edt2–favoring the former and pdt2–thelatter. Treatment of Fe(dithiolate)(CO)2(diphos) with theFe(0) reagent (benzylideneacetone)Fe(CO)3gave Fe2(dithiolate)(CO)4(diphos), thereby defining a route fromsimple ferrous salts to models for hydrogenase active sites. Extendingthe building block route to heterobimetallic complexes, treatmentof Fe(pdt)(CO)2(dppe) with [(acenaphthene)Mn(CO)3]+gave [(CO)3Mn(pdt)Fe(CO)2(dppe)]+([3d(CO)]+). Reduction of [3d(CO)]+with BH4–gave the Cs-symmetricμ-hydride (CO)3Mn(pdt)(H)Fe(CO)(dppe) (H3d). Complex H3dis reversibly protonated by strong acids,the proposed site of protonation being sulfur. Treatment of Fe(dithiolate)(CO)2(diphos) with CpCoI2(CO) followed by reductionby Cp2Co affords CpCo(dithiolate)Fe(CO)(diphos) (4), which can also be prepared from Fe(dithiolate)(CO)2(diphos) and CpCo(CO)2. Like the electronicallyrelated (CO)3Fe(pdt)Fe(CO)(diphos), these complexes undergoprotonation to afford the μ-hydrido complexes [CpCo(dithiolate)HFe(CO)(diphos)]+. Low-temperature NMR studies indicate that Co is the kineticsite of protonation. [ABSTRACT FROM AUTHOR]