Synthesis, characterization and some properties of mononuclear Ni and trinuclear NiFe2 complexes related to the active site of [NiFe]-hydrogenases?

Dalton Transactions Pub Date: 2012-05-22 DOI: 10.1039/C2DT30609C

Abstract

The [N2S2]-type ligand 1,2-(2-C5H4NCH2S)2C6H4 (L) is prepared in 84% yield by a new method and its structure has been confirmed by X-ray crystallography. The new synthetic method involves sequential reaction of 1,2-phenylenedithiol with EtONa followed by treatment of the resulting disodium salt of 1,2-phenylenedithiol with in situ generated 2-(chloromethyl)pyridine from its HCl salt. Further treatment of ligand L with NiCl2·6H2O or NiI2 affords the expected new mononuclear Ni complexes Ni[1,2-(2-C5H4NCH2S)2C6H4]Cl2 (1) and Ni[1,2-(2-C5H4NCH2S)2C6H4]I2 (3) in 87–88% yields, whereas reaction of L with NiBr2 under similar conditions results in formation of the expected new mononuclear complex Ni[1,2-(2-C5H4NCH2S)2C6H4]Br2 (2) and one unexpected new mononuclear complex Ni[1-(2-C5H4NCH2S)-2-(2-C5H4NCH2SC6H4S)C6H4]Br2 (2*) in 82% and 5% yields, respectively. More interestingly, the ligand L-containing novel trinuclear NiFe2 complex Ni{[1,2-(2-C5H4NCH2S)2C6H4}Fe2(CO)6(μ3-S)2 (4) is found to be prepared by sequential reaction of (μ-S2)Fe2(CO)6 with Et3BHLi, followed by treatment of the resulting (μ-LiS)2Fe2(CO)6 with mononuclear complex 1, 2, or 3 in 12–20% yields. The new complexes 1–4 and 2* are fully characterized by elemental analysis and various spectroscopies, and the crystal structures of 1, 2* and 3 as well as some electrochemical properties of 1–4 are also reported.

Graphical abstract: Synthesis, characterization and some properties of mononuclear Ni and trinuclear NiFe2 complexes related to the active site of [NiFe]-hydrogenases
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