A Tetranuclear Propane-1,3-Dithiolate Complex, [Fe2(CO)5{Ph2P(CH2)3}{(µ-SCH2)2CH2}]2, with a Bridging 1,6-Bis(diphenylphosphino)hexane Ligand

The 2:1 molar reaction of [Fe 2 (CO) 6 {( µ -SCH 2 ) 2 CH 2 }] ( 1 ) and a bidentate diphosphine ligand, 1,6-bis(diphenylphosphino)hexane (dpph), in the presence of Me 3 NO resulted in the isolation of [Fe 2 (CO) 5 {Ph 2 P(CH 2 ) 3 }{( µ -SCH 2 ) 2 CH 2 }] 2 ( 2 ) as red crystals in 71 % yield. The dpph ligand in compound 2 , coordinates two Fe 2 S 2 subunits as bridging mode and hence makes a linkage between two [Fe 2 (CO) 5 {( µ -SCH 2 ) 2 CH 2 }] fragments. Each Fe 2 S 2 butterfly of the complex consists of two fused Fe(S-C-C-C-S) six-membered rings, one of which attains a chair conformation, and the other is necessarily in a boat conformation. Compound 2 has unequivocally been characterized by elemental analysis, IR, 1 H NMR and 31 P NMR spectroscopy together with single crystal X-ray diffraction studies. Crystals of 2 are triclinic, space group P- 1, a = 9.918(4) Å, b = 10.347(3) Å, c = 14.581(5) Å, α = 72.239(12)º, β = 80.342(12)º, γ = 68.550(14)º and Z = 1. Graphic Abstract A novel tetranuclear propane-1,3-dithiolate complex, [Fe 2 (CO) 5 {Ph 2 P(CH 2 ) 3 }{(μ-SCH 2 ) 2 CH 2 }] 2 ( 2 ), bearing a bridging bis(diphenylphosphino)hexane (dpph) ligand, was synthesized from the Me 3 NO aided room temperature displacement of carbonyls from [Fe 2 (CO) 6 {(μ-SCH 2 ) 2 CH 2 }] ( 1 ), and structurally characterized.