| 18610969 |
Volkers PI, Boyke CA, Chen J, Rauchfuss TB, Whaley CM, Wilson SR, Yao H: Precursors to [FeFe]-hydrogenase models: syntheses of Fe2 (SR) 2 (CO) 6 from CO-free iron sources. Inorg Chem. 2008 Aug 4;47(15):7002-8. Epub 2008 Jul 9.
This report describes routes to iron dithiolato carbonyls that do not require preformed iron carbonyls. The reaction of FeCl 2, Zn, and Q 2S 2C n H 2 n (Q (+) = Na (+), Et 3NH (+)) under an atmosphere of CO affords Fe 2 (S 2C n H 2 n )(CO) 6 ( n = 2, 3) in yields > 70%. The method was employed to prepare Fe 2 (S 2C 2H 4)( (13) CO) 6. Treatment of these carbonylated mixtures with tertiary phosphines, instead of Zn, gave the ferrous species Fe 3 (S 2C 3H 6) 3 (CO) 4 (PR 3) 2, for R = Et, Bu, and Ph. Like the related complex Fe 3 (SPh) 6 (CO) 6, these compounds consist of a linear arrangement of three conjoined face-shared octahedral centers. Omitting the phosphine but with an excess of dithiolate, we obtained the related mixed-valence triiron species [Fe 3 (S 2C n H 2 n ) 4 (CO) 4] (-). The highly reducing all-ferrous species [Fe 3 (S 2C n H 2 n ) 4 (CO) 4] (2-) is implicated as an intermediate in this transformation. Reactive forms of iron, prepared by the method of Rieke, also combined with dithiols under a CO atmosphere to give Fe 2 (S 2C n H 2 n )(CO) 6 in modest yields under mild conditions. Studies on the order of addition indicate that ferrous thiolates are formed prior to the onset of carbonylation. Crystallographic characterization demonstrated that the complexes Fe 3 (S 2C 3H 6) 3 (CO) 4 (PEt 3) 2 and PBnPh 3 [Fe 3 (S 2C 3H 6) 4 (CO) 4] feature high-spin ferrous and low-spin ferric as the central metal, respectively. |
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