Indian Journal of Chemistry Vol. 46A, June 2007, pp. 937-941 Multinuclear NMR investigation on newly synthesized gold(I) pentafluorophenyl- arylazoimidazole complexes Prithwiraj Byabartta* & Mariano Laguna Departmento de Quimica Inorganica-Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain Email: prithwis33@yahoo.com Received 25 July 2006; 23 April 2007 Reaction of [Au(C 6 F 5 )(tht)] with RaaiR′ in dichloromethane yields [Au(C 6 F 5 )(RaaiR′)] [RaaiR′ = p-R-C 6 H 4 -N=N-C 3 H 2 -NN-1- R′, (1-3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively, R = H, Me, Cl and R′ = Me, CH 2 CH 3 , CH 2 Ph]. The maximum molecular peak of [Au(C 6 F 5 )(MeaaiMe)] is observed at m/z 564.01 in the FAB mass spectrum. IR spectra of the complexes show -C=N- and -N=N- stretching at 1590 and 1370 cm -1 and at 1510, 955, 800 cm -1 due to the presence of pentafluorophenyl ring. The 1 H NMR spectral measurements suggest that methylene group in RaaiEt gives a complex AB multiplet with coupling constant of 7.6 Hz, while in RaaiCH 2 Ph, it shows AB type quartets with coupling constant of 7.2 Hz. 13 C NMR spectrum of the complexes assign the molecular skeleton. In the 1 H- 1 H COSY spectrum of the present complexes, absence of any off-diagonal peaks extending from δ = 14.12 ppm and 9.55 ppm confirm no proton on N(1) and N(3) respectively. In the 1 H- 13 C HMQC spectrum, since there are no contours at δ = 157.12, 160.76, 155.67 ppm and 157.68—160.2 ppm, these may be assigned to the C(2), C(6), C(12) and C(13, 14, 15, 16 and 17) carbon atoms respectively. The solution structure and stereoretentive transformation in each step have been established from 1 H NMR data. The electrochemistry gives the ligand reduction peaks. IPC Code: Int. Cl. 8 C07F1/12; G01N24/00 Transition metal complexes of diimine and related ligands have attracted much attention 1-10 . There is tremendous interest in the synthesis of the complexes of gold with α-diimine type of ligands because of their photochemical, catalytic properties, energy conversion and ability to serve as building blocks in supramolecular arrays. Researchers have been engaged in modifying the properties of Au-pyridine complexes by replacing the ligands of other donor centres, altering the steric and electronic properties of the ligands. The search for a suitable precursor to synthesize azoimine-complexes is challenging and these compounds are found to be useful in this context. Recently, we have reported the arylazoimida- zole chemistry of ruthenium and have synthesised dichloro componds RuCl 2 (RaaiR′) 2 and diaquo species [Ru(OH 2 ) 2 (RaaiR′) 2 ] 2+ [RaaiR′ = p-R-C 6 H 4 -N=N- C 3 H 2 - NN-1-R′, (1-3), R = H (a), Me (b), Cl (c) and R′ = Me (1), CH 2 CH 3 (2), CH 2 Ph (3) abbreviated as N,N′-chelator where N(imidazole) and N(azo) represent N and N′, respectively]. Syntheses of hetero-tris-chelates, [Ru(bpy) n (RaaiR′) 3-n ](ClO 4 ) 2 [bpy = 2,2′-bipyridine; n = 1, n = 2) from the solvento complexes [Ru(OH 2 ) 2 (bpy) 2 ] 2+ / [Ru(OH 2 ) 2 (RaaiR′) 2 ] 2+ containing labile reaction centres have been reported 4-10 . Syntheses of molybdenum-bis- chelates with carbonyl, containing this ligand centres have also been reported earlier. However, the chemistry of gold and its organometallic chemistry with 1D 2D spectroscopy of this ligand system is totally unexplored. Herein, we report the reaction of RaaiR′ with gold(I) pentafluorophenyl derivatives . The complexes have been characterised by IR, H NMR, C NMR, H-H COSY NMR, H-C HMQC NMR and mass spectrometry. Experimental RaaiR′, [Au(C 6 F 5 )(tht)] was prepared by literature method 7-9,17-20 . All other chemicals and organic solvents used for preparative work were of reagent grade (SRL, Sigma Alhrich). Microanalytical data (C, H, N) were collected using a Perkin Elmer 2400 CHN instrument. IR spectra were obtained using Perkin Elmer spectrophotometer. 1 H NMR spectra in CDCl 3 were obtained on a Bruker 500 MHz FT NMR spectrometer using SiMe 4 as internal reference, CFCl 3 (external 19 F). Solution electrical conductivities were measured using a Systronics 304 conductivity. Mass spectra were recorded on a VG Autospec FAB instrument usuing 3-nitrobenzyl as matrix. (Pentafluorophenyl) {1-methyl-2-(p-tolylazo)imidazole}- aurate(I), [Au(C 6 F 5 ) (MeaaiMe)] To a colourless dichloromethne solution (15 cm 3 ) of [Au(C 6 F 5 )(tht)] (0.941 g, 0.20 mmol), was added a yellow dichloromethane solution of 1-methyl-2-(p- tolylazo)imidazole, (0.039 g, 0.20 mmol) slowly and the mixture was stirred at 343-353 K for 12 h. The red solution that resulted was concentrated (4 cm 3 ) and kept in a refrigerator overnight. The addition of