Synthesis, structural characterization, and properties of some functionalized phosphine-containing diiron complexes as models for the active site of [FeFe]-hydrogenases

摘要

The first phosphinobenzaldehyde- and phosphinoporphyrin-functionalized model complexes (1-4) have been synthesized and structurally characterized. Thus, reaction of diiron complex [(μ-SCH _2) _2CH _2]Fe _2(CO) _6 or [(μ-SCH _2) _2NC _6H _4CO _2Me-p]Fe _2(CO) _6 with p-Ph _2PC _6H _4CHO in the presence of Me _3NO gave the phosphinobenzaldehyde-functionalized model complexes [(μ-SCH _2) _2CH _2]Fe _2(CO) _5(p-Ph _2PC _6H _4CHO) (1) and [(μ-SCH _2) _2NC _6H _4CO _2Me-p]Fe _2(CO) _5(p-Ph _2PC _6H _4CHO) (2) in 61% and 71% yields, respectively. Further reaction of 1 or 2 with PhCHO, pyrrole, and BF _3?OEt _2 followed by treatment with p-chloranil resulted in formation of the phosphinoporphyrin-functionalized model complexes 5-{[(μ-SCH _2) _2CH _2]Fe _2(CO) _5(p-Ph _2PC _6H _4)}-10,15,20-triphenylporphyrin (3) and 5-{[(μ-SCH _2) _2NC _6H _4CO _2Me-p]Fe _2(CO) _5(p-Ph _2PC _6H _4)}-10,15,20-triphenylporphyrin (4) in 19% and 18% yields, respectively. While the new complexes 1-4 were characterized by elemental analysis and spectroscopy, the structures of 1, 3, and 4 were confirmed by X-ray crystallography. Particularly interesting is that complex 4 was found to be a catalyst for the photoinduced H _2 production in the presence of the electron donor EtSH and the proton source HOAc.