Iron(II)–nitrile complexes: synthesis, structure and property of trans-[FeH(NCR)(dppe)2]+X− (dppe=Ph2PCH2CH2PPh2: R=CH3, CH2CH2OCH3, CH2CH2CH2Cl, C6H5: X=Cl, BPh4, BF4)

Abstract

Dissolution of trans-FeHCl(dppe)2, 1, in various nitriles under argon led to the formation of complexes of the type trans-[FeH(NCR)(dppe)2]Cl (2a (R=CH3), 3a (R=CH2CH2OMe), 4a (R=CH2CH2CH2Cl), 5a (R=Ph)) in several hours. Complexes 2a–4a could be further converted to trans-[FeH(NCR)(dppe)2][BPh4] (2b–4b) and trans-[FeH(NCR)(dppe)2][BF4] (2c–4c) when they were treated with NaBPh4 and NaBF4, respectively. The stability and electrochemical properties of these complexes appeared to depend mainly on their counteranions (Cl−, BPh4−, BF4−). Compounds 2b, 2c, 3b, 3c, 4b and 4c reacted with KCN or NaCN to give [FeH(CN)(dppe)2] (6). Compound 6 underwent electrophilic addition at the cyano nitrogen by RSO3CF3 (R=Me, H) to give [FeH(CNR)(dppe)2][SO3CF3] (7a for R=Me, 7b for R=H). Crystallographic data for 2b: monoclinic space group P21/c, a=22.508(1) Å, b=16.120(1) Å, c=19.257(1) Å, β=113.86(1)°, Z=4, R(wR2)=0.0361(0.0882). Crystallographic data for 3b: triclinic space group P1̄, a=13.240(1) Å, b=14.732(2) Å, c=19.807(1) Å, α=75.276(6)°, β=72.466(6)°, γ=82.033(6)°, Z=2, R(wR2)=0.0368(0.0835). Crystallographic data for 7a: monoclinic space group P21/c, a=12.456(1) Å, b=21.880(3) Å, c=19.924(3) Å, β=108.08(1)°, Z=4, R(wR2)=0.0663 (0.1647).