Synthesis, crystal structure and DFT studies of a novel dinuclear copper(I) complex with triphenylphosphine and 2-mercaptonicotinic acid

Abstract A novel dinuclear copper(I) complex, {[Cu 2 (Mnt) 2 (PPh 3 ) 2 Cl 2 ].2H 2 O.CH 3 CN} 2 ( 1 ) (Mnt = Mercaptonicotinic acid, PPh 3  = triphenylphosphine) was prepared and its structure was determined by X-ray crystallography. The complex 1 consists of two dinuclear molecules and in each molecule, the two copper atoms are bridged by S atoms of N-protonated mercaptonicotinic acid forming a four-membered ring. The planar Cu 2 S 2 core is characterized by significant cuprophilic interactions (Cu Cu distance = 2.7671(8), 2.8471(8) A). Each copper atom in 1 is coordinated by two sulfur atoms of Mnt, one phosphorus atom of PPh 3 and a chloride ion adopting a tetrahedral geometry. The calculated Gibbs energies for reaction in CH 3 CN supported the experimental structure and predicted more favorable formation of dinuclear Cu(I) complex as compared to the mononuclear Cu(I) complex. The dinuclear complex is stabilized by 65.98 kJ mol −1  by coupling of two mononuclear Cu(I) complexes. The IR spectra of 1 and Mnt ligand were reliably interpreted and the Mnt vibrations, which are sensitive to the ligand coordination to Cu(I) ion in 1 were selected with the help of DFT/ωB97XD calculations.