The influence of benzaldehyde-N-alkyl-thiosemicarbazones on the synthesis of gold(I) ionic complexes: Spectroscopy, ESI-mass, structures and variable H-bonded polymeric networks.

The effect of the substituents at the N 1 /C 2 atoms of the thiosemicarbazones R 1 R 2 C 2 = N 3 -N 2 H-C 1 (=S)-N 1 HR 3 on the type of gold(I) complexes is investigated. Direct reaction of gold(I) chloride with benzaldehyde-N-methyl thiosemicarbazones (HL 1 : R 1 = Ph, R 2 = H, R 3 = Me) in a 1:2 M ratio in acetonitrile has yielded an ionic complex, [Au(κ 1 -S-HL 1 ) 2 ]Cl ( 1 ). Similarly, the reaction of benzaldehyde-N-ethyl thiosemicarbazone (HL 2 : R 1 = Ph, R 2 = H, R 3 = Et) has formed another ionic complex, [Au(κ 1 -S-HL 2 ) 2 ]Cl ( 2 ). The complexes have been characterized using analytical data, spectroscopy (IR, 1 H, 13 C NMR, UV–Vis), fluorescence, ESI-mass and X-ray crystallography. Complexes 1 and 2 represent the first examples obtained from the direct reactions of gold(I) chloride with a thio-ligand without the presence of PPh 3 or the use of any intermediate substrate, as has normally been used. Complex 1 , with a methyl substituent at N 1 , has two independent molecules in the crystal lattice, while complex 2 , with an N-ethyl substituent, has only one type of molecule in the crystal lattice. ESI-mass studies reveal the formation of the species: [Au I Cl+H] + ( A ), [Au I Cl 2 (HL 1 )+2H] + ( B ), [Au I (HL 1 ) 2 ] + ( C ) (complex 1 ) and [Au I (HL 2 ) 2 -4H] + ( D ) (complex 2 ). Interestingly both complexes have shown intense fluorescence bands in the wide region 340–540 nm, corresponding to the excitation wavelength of 308 nm. [ABSTRACT FROM AUTHOR]