675122-73-3Relevant academic research and scientific papers
An Expanded Set of Functional Groups in Bis(dithiolene)tungsten(IV,VI) Complexes Related to the Active Sites of Tungstoenzymes, Including W- IV-SR and WVI-O(SR)
Jiang, Jianfeng,Holm
, p. 1302 - 1310 (2004)
The active sites of tungstoenzymes have the formulations W IV,VL(S2pd)2 and WVILL′(S 2pd)2, in which two pyranopterindithiolene cofactor ligands (S2pd) are chelated to a tungsten atom. Ligands L and/or L′ are not fully defined in any wild-type enzyme. The feasibility of various coordination fragments (functional groups) in potential bis(dithiolene)tungsten site analogues has been examined in previous work by exploratory synthesis. This investigation expands the range of accessible functional groups. The synthetic scheme originates with [W(CO) 2(S2C2Me2)2], whose carbonyl groups are labile to substitution. Complexes [W IV,VILL′(S2C2Me2) 2]1- are described in terms of their functional groups WIV,VILL′. Reaction of the dicarbonyl with formate in acetonitrile/THF affords WIV(CO)(η1-HCO2) (4) and in Me2SO WVIO(η1-HCO2) (7) by an oxo transfer reaction. Carboxylates yield six-coordinate W IV(η2-O2CR) (1-3, R = Ph, Me, Bu t with C2v symmetry. Reaction of 3 (R = But with Me3SiSR (R = C6H2-2,4,6-Pr 3i) gives WIV(SR) (5), which undergoes oxo and sulfido atom transfer to form WVIO(SR) (8) and WVIS(SR) (9), respectively. Attempts to prepare corresponding selenolate complexes, pertinent to the active site of formate dehydrogenase, were unsuccessful, including reactions of WVIOCI (10) with RSe-. Structure proofs of 2-10 were obtained by X-ray structure determinations. Some 26 functional group types in bis(dithiolene)W(IV,V,VI) molecules have now been achieved by synthesis. It remains to be seen which are incorporated in an enzyme site. A number of them (e.g., 5) are directly analogous to molybdoenzyme sites, and may possess corresponding reactivity with biological substrates, as do WIV(OR)/WVIO(OR) (prepared earlier) in the reduction of N- and S-oxides by atom transfer.
