Reactivity of [Fe₂(CO)₆(μ-S₂)] toward a Base-Containing Diphosphine (Ph₂PCH₂)₂NCH₃: Formation of Diiron Carbonyl Compounds Having Polydentate Heterofunctionalized Phosphine (PNS = Ph₂PCH₂N(CH₃)CH₂S) and Bidentate Thiophosphinito (Ph₂PS = PS) Bridges

Abstract

Reaction of the base-containing diphosphine (Ph 2 PCH 2 ) 2 NCH 3 with [Fe 2 (CO) 6 (μ-S 2 )] (1) yielded at room temperature the novel compound [Fe 2 (CO) 4 (μ-κ 1 :κ 1 -SPPh 2 ){μ-κ 2 :κ 2 -SCH 2 N(Me)CH 2 -PPh 2 }] (2) resulting from S-S and P-C bond cleavage concomitant with P-S and C-S bond formation. Experiments at low temperature allowed the isolation of an intermediate species, [Fe 2 (CO) 5 -(μ-κ 1 :κ 1 -SPPh 2 ){μ-κ 2 :κ 1 -SCH 2 N(Me)CH 2 PPh 2 }] (3), differing from 2 by the coordination mode of the PNS ligand and the presence of one additional carbonyl group. When the reaction was performed in the presence of an excess of tBuNC, an analogous compound of 3 was obtained. The X-ray analysis of this species, 4, revealed that an isocyanide replaced a carbonyl ligand in the axial position at one iron center.

Diiron species containing a cyclic PPh2NPh2diphosphine related to the [FeFe]H2ases active site

“…The formation of this product could arise from partial decomposition of dithiolate diiron compounds. 11 Unfortunately, until now, only very small single crystals of 2 were obtained. For this reason, 2 could not be identified without any ambiguity.…”

Computational and Experimental Investigations of the Fe2(μ-S2)/Fe2(μ-S)2 Equilibrium

“…Compared to Fe 2 (SR) 2 (CO) 6 -type complexes, diiron complexes of μ-R 2 PS ligands feature elongated Fe−Fe distances by as much as 0.2 A. 32,33 Very relevant to the conversion 1 + dppv → 7 is the work of Schollhammer et al, who efficiently generated Ph 2 PS-bridged diiron complexes in good yields from the reaction of 1 and MeN(CH 2 PPh 2 ) 2 (eq 3). 32 ■ SUMMARY Theory provides guidance for the stabilization of low-spin diferrous disulfides.…”

“…32,33 Very relevant to the conversion 1 + dppv → 7 is the work of Schollhammer et al, who efficiently generated Ph 2 PS-bridged diiron complexes in good yields from the reaction of 1 and MeN(CH 2 PPh 2 ) 2 (eq 3). 32 ■ SUMMARY Theory provides guidance for the stabilization of low-spin diferrous disulfides. The concept is simple even if the experimental verification is not; relative to Fe(I)S(−I), Fe(II)(S−II) is stabilized by the increased basicity of the ligands on iron.…”

“…A final aspect of this work is the unusual course of the reaction of Fe 2 (μ-S 2 )(CO) 6 and dppv (and at least one other diphosphine). 32 These results point to highly reactive intermediates in the reaction of Fe 2 (μ-S 2 )(CO) 6 with phosphines. Even the reaction of Fe 2 (μ-S 2 )(CO) 6 with triphenylphosphine remains shrouded in mystery, as it has been speculated to yield an adduct Fe 2 (μ-S 2 )(CO) 6 (μ-PPh 3 ).…”

Using polyethyleneimine (PEI) as a scaffold to construct mimicking systems of [FeFe]‐hydrogenase: preparation, characterization of PEI‐based materials, and their catalysis on proton reduction

“…In mimicking the natural systems, particular attention has been paid to the preparation of mimics possessing a basic group either directly coordinating to the diiron center or locating in the secondary coordination sphere because it is believed that such a group may play a role in proton transfer in the process of proton reduction and hence improve catalytic efficiency. Wherever the base groups are located in the mimics, studies demonstrated that those groups were actively involved in the protonation of the mimics . An important consideration is that the base group in a model complex may initiate a proton‐coupled electron transfer process in catalysis.…”