Note Cd(II)–NCS/NCO complexes of 1-alkyl-2-(arylazo)imidazole: Single crystal X-ray structure of [Cd(HaaiMe) 2 (SCN) 2 ] Kamal Krishna Sarker a , Brojo Gopal Chand a , Atish Dipankar Jana b , Golam Mostafa b , Chittaranjan Sinha a, * a Department of Chemistry, Jadavpur University, Jadavpur, Raja Suboth Mullick Road, Kolkata, West Bengal 700 032, India b Department of Physics, Jadavpur University, Jadavpur, Raja Suboth Mullick Road, Kolkata, West Bengal 700 032, India Received 7 June 2005; received in revised form 1 October 2005; accepted 9 October 2005 Available online 29 November 2005 Abstract The reaction of Cd(OAc) 2 Æ 4H 2 O and 1-alkyl-2-(arylazo)imidazole [RaaiR 0 where R = H (a), Me (b); R 0 = Me (1/3/5), Et (2/4/6)] and NH 4 NCS/NaNCO in methanol in 1:2:2 mole ratio has afforded [Cd(RaaiR 0 ) 2 (NCS) 2 ](3, 4) and [Cd(RaaiR 0 ) 2 (NCO) 2 ](5, 6) complexes. The complexes are characterized by different physicochemical methods and in one case, the structure was confirmed by single crystal X-ray diffraction study for title compounds. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Arylazoimidazoles; Cadmium(II) complexes; Octahedral; X-ray 1. Introduction We are interested to design imidazole-containing ligands. There are two basic reasons to concentrate on imidazole type systems: biochemical ubiquity and an alternative to polypyridines. The metal complexes of polypyridines have received much attention because of rich electrochemistry, interesting optical properties, bioin- organic chemistry and catalyses [1–7]. This has led to the modification of the ligand system inserting different sub- stituents, presence of other donor centers etc [7–13]. Ligand synthesis using imidazole as heterocyclic back- bone is of much advantage because of the biochemical importance of this molecule [14,15]. Imidazole carries meta-related two N centers of different basicity and can bind strongly heavy metal ions [16,17]. We have designed a surface modified extractant by anchoring imidazole to polystyrene by azo group (–N@N–) and have been used for the separation of heavy metals from drinking water, environmental samples, medicinal samples and ores, min- erals [18]. The fundamental property of interaction between metal ions and organic ligands has been utilized in the design of functional materials. Azoimidazoles is one such system. It has also been used to extract anions through protonation of imidazole motif and subsequent interaction with anions via hydrogen bonding [19]. The exo-bidentate behaviour of the ligand has been elimi- nated by N(1)-alkylation. The coordination chemistry of 1-alkyl-2-(arylazo)imidazoles (RaaiR 0 ) has been stud- ied by us [20–26] and others [27,28] using transition metals. In RaaiR 0 , the active function is the azoimine group (–N@N–C@N–) which is isoelectronic with diimine func- tion (–N@C–C@N–). The non-transition metal complexes of arylazoimidazole has been reported recently by us [29– 32]. This ligand acts as a potential bidentate chelator with 0020-1693/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2005.10.019 * Corresponding author. Tel.: +91 033 2414 6666x2453; fax: +91 033 2414 6584. E-mail address: c_r_sinha@yahoo.com (C. Sinha). www.elsevier.com/locate/ica Inorganica Chimica Acta 359 (2006) 695–700