New Class of Hydrido Iron(II) Compounds with cis‐Reactive Sites: Combination of Iron and Diphosphinodithio Ligand

Abstract

The cationic complex [Fe(P2 S2 )(NCMe)2 ](2+) (P2 S2 =(Ph2 PC6 H4 CH2 S)2 (C2 H4 ) ([1(NCMe)2 ](2+) )), with two MeCN ligands in a cis orientation, was synthesized and characterized. The MeCN ligand in [1(NCMe)2 ](2+) undergoes further substitution by a hydride ligand or CO to give iron(II) hydrides [H1(NCMe)](+) , [H1H](0) , and [H1(CO)](+) . The order of reactivity of the hydrides was [H1H](0) >[H1(NCMe)](+) >[H1(CO)](+) , and was illustrated by their reactions toward protic acids, the organic cation of 10-methylacridinium (MeAcr(+) ) as a hydride acceptor, and intermolecular hydride transfer reactions among these ferrous compounds. For example, MeAcr(+) was reduced initially by a one-electron transfer process from [H1H](0) , resulting in competing reactions of MeAcr(.) dimerization, hydrogen atom transfer from [H1H](+) to MeAcr(.) , and decomposition of [H1H](+) . MeAcrH was produced in excellent yields through a single-step H(-) transfer from [H1(NCMe)](+) to MeAcr(+) , but [H1(CO)](+) was inactive toward MeAcr(+) .

Nickel-Mediated Stepwise Transformation of CO to Acetaldehyde and Ethanol

“…Owing to its soft and flexible coordination properties, the phosphine-thioether ligand has been investigated intensively for group 10 metals such as Pd or Pt . In our previous study, we found that the tetradentate ligand (Ph 2 PC 6 H 4 CH 2 S) 2 (C 2 H 4 ), abbreviated as P 2 S 2 , coordinated with iron­(II) to form the cationic complex [(P 2 S 2 )­FeH­(CO)] + folded in such a way that the hydride and CO ligand are in a cis -α disposition . The dicationic complex [Ni­(P 2 S 2 )]­(BF 4 ) 2 ([ 1 ] 2+ ) was prepared by the straightforward treatment of a solution of P 2 S 2 in THF with a solution of Ni­(BF 4 ) 2 ·6H 2 O in isopropanol.…”

“…All reagents were purchased from Sigma-Aldrich and used as received. (Ph 2 PC 6 H 4 CH 2 S) 2 (C 2 H 4 ) was prepared according to our previous methods . Et 2 O, pentane, THF (dried by distillation over sodium), MeCN (dried by distillation over CaH 2 ), and CH 2 Cl 2 for general use were of analytical (AR) grade and stored under N 2 atmosphere.…”

“…26 In our previous study, we found that the tetradentate ligand (Ph 2 PC 6 H 4 CH 2 S) 2 (C 2 H 4 ), abbreviated as P 2 S 2 , coordinated with iron(II) to form the cationic complex [(P 2 S 2 )FeH(CO)] + folded in such a way that the hydride and CO ligand are in a cis-α disposition. 27 The dicationic complex [Ni(P 2 S 2 )](BF 4 ) 2 ([1] 2+ ) was prepared by the straightforward treatment of a solution of P 2 S 2 in THF with a solution of Ni(BF 4 ) 2 •6H 2 O in isopropanol. The molecular structure of [1] 2+ was established by single-crystal X-ray diffraction, which showed that the Ni(II) center adopts a distorted-tetrahedral geometry instead of the square-planar geometry common in four-coordinate nickel(II) complexes (Figure 1).…”

Iron Dihydride Complexes: Synthesis, Reactivity, and Catalytic Applications

“…Changing the backbone of tetraphos to a thioether‐based linkage resulted in a more flexible tetradentate ligand P 2 S 2 (Figure ). The corresponding iron dihydride, which was synthesized from the cationic acetonitrile complex and Bu 4 NBH 4 , was shown to adopt the cis geometry for the hydride ligands …”

“…Cis ‐(P 2 S 2 )FeH 2 was reported to lose H 2 gradually in solution over the time . Protonation of one of the hydride ligands was readily accomplished in MeCN using a weak acid such as a protonated phosphazene, leading to the formation of cis ‐[(P 2 S 2 )FeH(MeCN)] + .…”