Indian Journal of Chemistry Vol. MA . August 2005. pp. 1561-1564 - Synthesis and structure of a dinuclear nickel(II) complex with an unusual type of double [NAr2] bridges Srijit Das I, Shie-Ming Peng 2 • Gene-Hsiang Lee 2 & Sreebrata Goswami I * I Department of Inorganic Chemistry. Indian Association for the Cultiv; ion of Science. Kolkata 700 032 . India 2Dcpartmcnt of Chcmistry. National Taiwan University. Taipei, Taiwan. Republic of China Email: icsg@iacs.res.in Received 22 March 2005; revised 20 May 2005 The reaction of equimolar quantities of Ni(CI0 4 )z '6 H z O, NaN, and a deprotonated tetradcntate bridging N-donor li- gand. [L2r. HL 2 =2-[2-(pyridylamino)phenylazo]pyridine. produces a novel di-metallic Ni rcomplex having double [NAr21 bridges. Thc complex has been isolated and suitable X-ray quality crystals grown through slow evaporation of the conccn- trated acetonitrile solution of the compound. The complex has been characterized fully using its physicochemical properties as well as si ngle crystal X-ray data analysis. lis structure reveals that the two deprotonated secondary amine nitrogens. viz. N(4) and N(9) of two fL2r bind two Ni(lI) centers simultancously forming planar Ni 2N2 arrangement. The complex is par- amagnetic and its solution exhibits blue colour, which shows charge-transfer transitions ncar 600 nm. IPC Code: Inl. Cl 7 C07 F 15/04 Double-bridged dinuclear complexes having M 2 (J.!-NR 2 h core with octahedral coordination geometry around the metal atoms are scarce l . 3 . We report here a di-nickel system, where each of the two nickel centers are octahedraly surrounded by the lig- ands and these two are bridged across two [NAr z] functions. During the recent years, we have been in- terested-l·7 in the coordination chemistry of the ligand, HL'. rn comparison, the ligand HL2 has an additional pyridyl function, separated by three atoms from the secondary amine nitrogen (Scheme 1) . Hence a bridging coordination mode of its conjugate base, [L2r may be anticipated. Materials and Methods All solvents and chemicals used for synthesis were of analytical grade. The ligand HL2 was prepared following the reported procedure 8 . A JASCO V -570 spectrometer was used to record electronic spectra. Q N=N N-Ar H b HL Scheme 1 The IR spectra were obtained with a Perkin-Elmer 783 spectrophotometer. A Perkin-Elmer 240C elemental analyzer was used to collect micro analyti- cal data (C, H, N). ESI mass spectra were recorded on a micro mass Q-TOF mass spectrometer (Serial No. YA 263). Determination of crystal structure X-ray quality crystals of di-nickel complex were obtained through the slow evaporation of the concen- trated acetonitrile solution of the compound. The data were collected on a NONIUS Kappa CCD dim'acto- meter equipped with MoKa radiation (I-. = 0.71073 A). A total of 26748 reflections were collected out of which 7875 were unique (Rim = 0.0396) and used in subsequent analysis. The structure was solved using the program package 9 " SHELXS-97 and refined by full-matrix least-squares techniques against F2 using SHELXL-97 9b . The crys- tal data of [Ni zC N 3 h(e h]: Empirical formula: C 34 H 27 N 17Ni 2, M = 791.15, monoclinic, P2 1 I e, a = 20.1465(2), b = 10.0525(1), e = 18.8362(2) A, f3 = 115.8568(5)°, V = 3432.85(6) A 3 , Z = 4, D, = 1.531 mg m· 3 , RIP >20'(1)] = 0.0428, wR 2 [1 >20'(1)] = 0.1034, GOF = 1.198. Crystallographic data of [Ni 2 (N 3 ML 2 hl have been deposited with the Cambridge Crystallographic Data Centre, CCDC No. 265373.