Syntheses, characterization, and electrochemistry of compounds containing 1-diphenylphosphino-1′-(di- tert -butylphosphino)ferrocene (dppdtbpf)

The reaction of copper(I) salts CuX (X = Cl, Br, I, CN, SCN), [Cu(CH3CN)4]PF6 with 1-diphenylphosphino-1′-di-tert-butylphosphinoferrocene (dppdtbpf) in 1:1 M ratio in DCM–MeOH (50:50 V/V) at room temperature afforded mono and binuclear compounds having formula [Cu2(μ-Cl)2(κ2-P,P-dppdtbpf)2] (1), [Cu2(μ-Br)2(κ2-P,P-dppdtbpf)2] (2) [Cu2(μ-I)2(κ2-P,P-dppdtbpf)2] (3), [Cu2(μ-CN)2(κ2-P,P-dppdtbpf)2] (4), [Cu2(μ2-SCN)2(κ2-P,P-dppdtbpf)2] (5), and [Cu(κ2-P,P-dppdtbpf)(CH3CN)2]PF6 (6). Reacting palladium(II) complex [Pd(C6H5CN)2Cl2] with dppdtbpf gave mononuclear compound [Pd(κ2-P,P-dppdtbpf)Cl2] (7). The reaction of dppdtbpf with sulfur powder under reflux in chloroform afforded a ferrocene diphosphine disulfide dppSdtbpSf (8). All of the synthesized compounds were characterized by elemental analyses, IR, 1H and 31P NMR, ESI-MS and electronic absorption spectroscopy. Molecular structures for the compounds 5, 6, 7 and 8 were determined crystallographically. Compound 5 exists as centrosymmetric dimer in which the two copper atoms are bonded to two dppdtbpf ligands and two bridging thiocyanate groups in μ2-manner. In cationic compound 6, the copper atom is coordinated to one dppdtbpf ligand in κ2-manner and two acetonitrile molecules, whereas in 7, the palladium(II) adopted cis square-planar geometry by coordinating to one dppdtbpf ligand in κ2-manner and two chlorine atoms. Compound 8 revealed a sandwiched structure with both phosphine groups sulfurized. The electrochemical properties of 1–6 were studied by cyclic voltammetry. Compounds 1–6 exhibited moderately weak to strong luminescence properties, however compounds 7 and 8 are non-emissive in the solution state.