Novel reactions of homodinuclear Ni₂complexes [Ni(RN_PyS₄)]₂with Fe₃(CO)₁₂to give heterotrinuclear NiFe₂and mononuclear Fe complexes relevant to [NiFe]- and [Fe]-hydrogenases

Abstract

The homodinuclear complexes [Ni(RNPyS4)]2 (; RNPyS4 = 2,6-bis(2-mercaptophenylthiomethyl)-4-R-pyridine; R = H, MeO, Cl, Br, i-Pr) were found to be prepared by reactions of the in situ generated Li2[Ni(1,2-S2C6H4)2] with 2,6-bis[(tosyloxy)methyl]pyridine and its substituted derivatives 2,6-bis[(tosyloxy)methyl]-4-R-pyridine. Further reactions of with Fe3(CO)12 gave both heterotrinuclear complexes NiFe2(RNPyS4)(CO)5 () and mononuclear complexes Fe(RNPyS4)(CO) (), unexpectedly. Interestingly, complexes and could be regarded as models for the active sites of [NiFe]- and [Fe]-hydrogenases, respectively. All the prepared complexes were characterized by elemental analysis, spectroscopy, and particularly for some of them, by X-ray crystallography. In addition, the electrochemical properties of and as well as the electrocatalytic H2 production catalyzed by and were investigated by CV techniques.

Reactions of dinuclear Ni2complexes [Ni(RNPyS4)]2(RNPyS4= 2,6-bis(2-mercaptophenylthiomethyl)-4-R-pyridine) with Fe(CO)3(BDA) (BDA = benzylidene acetone) leading to heterodinuclear NiFe and mononuclear Fe complexes related to the active sites of [NiFe]- and [Fe]-hydrogenases

“…In one moiety [Ni(BzON Py S 4 )] the Ni1 center is coordinated by thiolate S2/S3 atoms, thioether S1/S4 atoms, and pyridine N1 atom, whereas in another moiety the Ni1A center is coordinated by thiolate S2A/S3A atoms, thioether S1A/S4A atoms, and pyridine N1A atom. The Ni1-N1 and Ni1A-N1A bond lengths are 2.0770Å, which is very close to those corresponding to its analogue 1e (2.087Å) 53 and parent complex 1a 54 (2.060Å).…”

“…4 and S1 † that both 3f and 3g contain only one iron (Fe1) center that is coordinated by a 4-substituted pyridine N1 atom, two thioether (S2/S4 atoms for 3f; S1/S3 atoms for 3g), two thiolate (S1/S3 atoms for 3f; S2/S4 atoms for 3g) and one terminal carbonyl ligand. The Fe1-N1 bond lengths of 3f (2.0121Å) and 3g (2.015Å) are very close to those of their analogues 3b (2.0128 A) and 3c (1.9972Å) 53 and their parent complex 3a (2.014Å). 54 Particularly noteworthy is that the coordination mode of the terminal carbonyl C1O1 in 3f or 3g is trans to the pyridine N1 atom, which is identical with that of one of the two terminal carbonyls present in the active site of [Fe]-hydrogenase.…”

“…Both 1f and 1g have been characterized by elemental analysis, IR, and mass spectrometry. For example, the elemental analysis indicated that 1f and 1g, in contrast to 1a-1d but consistent with 1e, 53,54 do not contain one molecule of MeOH due to their purication being by recrystallization from a mixed solvent, CH 2 Cl 2 -hexane. In addition, the mass spectra of 1f and 1g showed their molecular ion peaks at m/z 1099.9 and 979.7, respectively.…”

“…53,54 All complexes 2b-2g and 3a-3g are readily soluble in THF and CH 2 Cl 2 , sparingly soluble in Et 2 O, but not soluble in hexane. New complexes 2b-2g, 3f, and 3g were characterized by elemental analysis, and IR and 1 H NMR spectroscopic methods.…”

“…[41][42][43][44][45][46][47][48][49][50][51][52] Recently, we reported a novel type of reactions of the [RN Py S 4 ] ligand-containing homodinuclear complexes [Ni(RN Py S 4 )] 2 (RN Py S 4 ¼ 2,6-bis(2-mercaptophenylthiomethyl)-4-R-pyridine, R ¼ H, MeO, Cl, Br, i-Pr) with homotrinuclear carbonyl complex Fe 3 (CO) 12 ; as a result, the reactions gave not only the [RN Py S 4 ] ligand-containing heterotrinuclear [NiFe]-hydrogenase model complexes NiFe 2 (RN Py S 4 )(CO) 5 , but also mononuclear [Fe]-hydrogenase model complexes Fe(RN Py S 4 )(CO). 53 To examine the inuence of the other iron carbonyl complex upon this type of reactions and to prepare the more natural heterodinuclear [Fe]-hydrogenase model complexes Fe(RN Py S 4 )CO 3 have been prepared by the studied reactions. Herein we report the detailed procedures for synthesis of the aforementioned complexes.…”