Synthetic and Structural Investigations on Double- and Single-Butterfly Fe/E (E = S, Se) Cluster Complexes Containing Diselenolate Ligands

Abstract

The first examples of diselenolate ligand-containing butterfly Fe/E (E = S, Se) complexes are now reported. When ca. 1 equiv of dilithium reagent 4-LiC6H4C6H4Li-4‘ containing n-BuBr (prepared from 1 equiv of 4,4‘-dibromobiphenyl and n-BuLi) was treated with 2 equiv of elemental selenium and Fe3(CO)12 followed by treatment with excess CS2 and MeI, both double-butterfly complex (4-μ-SeC6H4C6H4Se-μ-4‘)[(μ-SCSMe)Fe2(CO)6]2 (4) and single-butterfly complex (4-n-BuSeC6H4C6H4Se-μ-4‘)[(μ-SCSMe)Fe2(CO)6] (4*) were produced in 11% and 20% yields, respectively. However, when ca. 1 equiv of dilithium reagent 4-LiC6H4C6H4Li-4‘ without n-BuBr (n-BuBr was removed by evaporation of the initially prepared dilithium reagent containing n-BuBr) reacted with 2 equiv of elemental selenium and Fe3(CO)12 followed by treatment with excess CS2 and MeI, only the double-butterfly complex 4 was obtained in a higher yield (21%) without any single-butterfly complex being isolated. Other double-butterfly complexes, such as (4-μ-SeC6H4C6H4Se-μ-4‘)[(μ-SCSR)Fe2(CO)6]2 (5, R = Et; 6, PhCH2; 7, PhCNPh; 8, Cp(CO)2Fe), (4-μ-SeC6H4C6H4Se-μ-4‘)[(μ-SePh)Fe2(CO)6]2 (9), and (4-μ-SeC6H4C6H4Se-μ-4‘)[(μ-CH2SMe)Fe2(CO)6]2 (10), could be similarly prepared via the latter method by using electrophiles CS2/EtBr, CS2/PhCH2Br, CS2/PhC(Cl)NPh, CS2/Cp(CO)2FeI, PhSeBr, and MeSCH2Cl instead of CS2/MeI, respectively. A possible pathway for production of the double- and single-butterfly complexes 4−10 and 4* has been proposed, in which the versatile two-μ-CO-containing double-butterfly dianion (4-μ-SeC6H4C6H4Se-μ-4‘)[(μ-CO)Fe2(CO)6]2 2- (3) and the one-μ-CO-containing single-butterfly monoanion (4-n-BuSeC6H4C6H4Se-μ-4‘)[(μ-CO)Fe2(CO)6]- (3*) are involved. All the new complexes were fully characterized by elemental analysis and spectroscopy, as well as by X-ray crystallography for 4* and 10.

Interaction of the active site of the Ni–Fe–Se hydrogenase from Desulfovibrio vulgaris Hildenborough with carbon monoxide and oxygen inhibitors

“…In addition, their comparative study with standard NiFe hydrogenases is very helpful for research in synthesis of biomimetic organometallic complexes with selenoate/thiolate ligands [10,11]. Moreover, Ni-Fe-Se hydrogenases immobilized on electrodes or on nanoparticles have interesting applications as biocatalysts for H 2 -production [12,13].…”

Diiron Complexes Bearing Bridging Hydrocarbyl Ligands as Electrocatalysts for Proton Reduction

“…The most striking change, in comparison to the classic model system, is replacement of dithiolate ligands with bridging hydrocarbyls, which might be crucial in consideration of the major role of dithiolate ligands in model systems. Thiolates have been replaced by diphosphide, diselenide, and diammide ligands, but the effects of bridging hydrocarbyl ligands in place of dithiolates can be hardly predicted. Indeed, among cyclopentadienyl diiron complexes, only the compound [Fe 2 (μ-CO) 2 (CO) 2 (Cp) 2 ] has been investigated and found to be a precatalyst for electrocatalytic hydrogen evolution.…”

Recent studies on chemistry of novel μ-CO-containing butterfly Fe/E (E = S, Se, Te) cluster salts

“…However, when it reacts with electrophiles without a leaving group such as CS 2 , another dilithium salt m 12 •Li 2 is generated, which reacts further with electrophiles such as EtBr to give the corresponding double butterfly cluster complex 12 (Scheme 11). The 77 Se NMR spectra of complexes 11 and 12 each exhibit only one singlet at 462 and 477 ppm, which implies that the chemical environments around the two bridged Se atoms involved in their two butterfly cluster cores are basically identical [26] .…”

“…Recent study has demonstrated that dilithium salt of double butterfly two µ-CO-containing Fe/Se cluster dianion C can be prepared by reaction of one mole of dilithium reagent 4-LiC 6 H 4 C 6 H 4 Li-4′ with two moles of Fe 3 (CO) 12 in THF from −15ºC to room temperature [26] . Similar to cluster salts B⋅[Et 3 NH] 2 , when dilithium salt of dianion C reacts with a leaving group-containing electrophiles such as MeSCH 2 Cl, intermediate m 11 is first formed by elimination of LiCl, and then the corresponding double butterfly cluster complex 11 can be produced by subsequent loss of µ-CO from m 11 .…”

“…The biphenylene group is attached to Se1 and Se1A by an equatorial type of bond , whereas the methyl groups are bound to S1 and S1A by an axial type of bond [19,20,26] . …”