Synthesis and coordination of a hybrid phosphinoferrocene sulfonamide ligand

In order to expand the family of hybrid phosphinoferrocene ligands, a novel phosphinoferrocene sulfonamide ligand, Ph2PfcNHSO2Me (1, fc = ferrocene-1,1′-diyl), was synthesised through a reaction between P-protected phosphinoamine Ph2PfcNH2·BH3 and MeSO2Cl followed by deprotection of the Ph2PfcNHSO2Me·BH3 (2) intermediate. Compound 1 coordinates as a functional phosphine ligand, producing Pd(II) complexes [PdCl(μ-Cl)(1-κP)]2 (4) or [PdCl2(1-κP)2] (5) from [PdCl2(cod)] (cod = cycloocta-1,5-diene) depending on the stoichiometry. The reaction of 1 with [(LNC)Pd(μ-Cl)]2 also produces a phosphine complex, [(LNC)PdCl(1-κP)] (6; LNC = 2-[(dimethylamino-N)methyl]phenyl-κC1), which was converted into the neutral bis-chelate complex [(LNC)Pd(Ph2PfcNSO2Me-κ2P,N)] (7) upon treatment with potassium tert-butoxide; the corresponding cationic chelate [(LNC)Pd(Ph2PfcNHSO2Me-κ2P,O)]+ could not be isolated. All compounds were characterised by elemental analysis and spectroscopic methods (NMR, IR and MS). In addition, the crystal structure of 1, 2, and 4–7 were determined (for solvated compounds in some cases), and the electrochemical properties of 1, 2, 6 and 7 were studied by cyclic voltammetry.