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

The cationic complex Fe(P₂S₂)(NCMe)₂]²⁺ (P₂S₂=(Ph₂PC₆H₄CH₂S)₂(C₂H₄) ( 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 H 1 (NCMe)]⁺, H 1 H]⁰, and H 1 (CO)]⁺. The order of reactivity of the hydrides was H 1 H]⁰>H 1 (NCMe)]⁺>H 1 (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 H 1 H]⁰, resulting in competing reactions of MeAcr^. dimerization, hydrogen atom transfer from H 1 H]⁺ to MeAcr^., and decomposition of H 1 H]⁺. MeAcrH was produced in excellent yields through a single‐step H^? transfer from H 1 (NCMe)]⁺ to MeAcr⁺, but H 1 (CO)]⁺ was inactive toward MeAcr⁺.