Synthesis of Mono- and Diiron Dithiolene Complexes as Hydrogenase Models by Dithiolene Transfer Reactions, Including the Crystal Structure of [{Ni(S₂C₂Ph₂)}₆]

Abstract

The dithiolene transfer reaction between the nickel bis(dithiolene) complex [Ni(S 2 C 2 Ph 2) 2 ] and iron carbonyls has been reinvestigated and the conditions for the production of the dinuclear product [Fe 2 (µ-S 2 C 2 Ph 2)(CO) 6 ] have been optimised. Interception of a purple intermediate, thought to be [Fe(CO) 3 (S 2 C 2 Ph 2)], in the reaction of [Fe(CO) 5 ] with [Ni(S 2 C 2 Ph 2) 2 ] by the addition of PPh 3 affords the new dark blue mononuclear complex [Fe(CO) 2 (PPh 3)(S 2 C 2 Ph 2)] in good yield. The fate of the nickel dithiolene fragments in these reactions has also been established by crystallographic characterisation of the hexamer [{Ni(S 2 C 2 Ph 2)} 6 ] and the trinuclear cluster [Ni 3 (µ-S 2 C 2 Ph 2) 3 (PPh 3) 2 ]. The substitution reactions of [Fe 2 (µ-S 2 C 2 Ph 2)(CO) 6 ] with PPh 3 in the presence of Me 3 NO to give monosubstituted [Fe 2 (µ-S 2 C 2 Ph 2)(CO) 5 (PPh 3)] and disubstituted [Fe 2 (µ-S 2 C 2 Ph 2)(CO) 4 (PPh 3) 2 ] are also reported.

Group 10 Metal Dithiolene Bis(isonitrile) Complexes: Synthesis, Structures, Properties, and Reactivity

“…These molecules have been of considerable usefulness as entry points toward small-molecule analogues of the catalytic sites of molybdo- and tungstoenzymes . Others, − particularly Morris and co-workers, − have effectively exploited this behavior for the preparation of a variety of new organometallic and inorganic transition-metal complexes. In these examples, the value-added product is the coordination complex formed by oxidative addition of the dithiolene ligand, while [(R 2 C 2 S 2 )­M] x is separated as an oligomeric or insoluble polymeric byproduct.…”

“…1 These molecules have been of considerable usefulness as entry points toward small molecule analogues of the catalytic sites of molybdoand tungstoenzymes. 2 Others, [3][4][5][6][7][8] particularly Morris and coworkers, [4][5][6][7][8] have effectively exploited this behavior for the preparation of a variety of new organometallic and inorganic transition metal complexes.…”

“…Yield: 0.079 g, 80%. 1 (8). Via a gastight syringe, 2,6-dimethylpyridine (0.500 mL, 4.32 mmol) was delivered dropwise to a solution of 4a (0.050 g, 0.130 mmol) in toluene (25 mL) under an argon atmosphere.…”

A Mixed-Valence Tetra-Nuclear Nickel Dithiolene Complex: Synthesis, Crystal Structure, and the Lability of Its Nickel Sulfur Bonds

“…Such behavior was also proposed and discussed for the molybdopterin ligand coordinated to molybdenum or tungsten concurrent with enzymatic turnover processes [12]. More recently, dithiolene ligands were employed in bioinorganic model chemistry targeting hydrogenase enzymes' active sites [13]. Nickel, as a bio-metal, is most often found in combination with sulfur donor atoms, including Ni-Fe hydrogenases, in which the nickel ion and the iron ion of the active site are bridged by cysteinate sulfur atoms.…”

“…H NMR (CDCl 3 , 300 MHz): δ, ppm = 7.94-8.05 (m, ortho-phenyl, 2H), 7.55-7.67 (m, para-phenyl, 1H), 7.43-7.54 (m, meta-phenyl, 2H), 5.73 (s, -CHBr, 1H), 4.27 (q, J = 6.9 Hz, -CH 2 , 2H), 1.23 ppm (t, J = 7.2 Hz, -CH 3 , 3H) 13. C NMR (CDCl 3 , 75 MHz): δ, ppm = 187.9 (PhC=O), 164.8 (C=O), 134.0 (C-phenyl), 133.0 (C-phenyl), 128.8 (C-phenyl), 128.6 (C-phenyl), 62.9 (CH 2 ),46.2 (CHBr), 13.5 (CH 3 ).…”