Cadmium(II) Chloride Adduct with an Olefinic Double Betaine: catena-Poly[tetraaquadiethanoltris[dichlorocadmium(II)] cis-bis(4-dimethylamino-1-pyridinio)butenedioate hydrate]

Abstract

Table 2. Selected geometric parameters (,4, o) Mt>--N 2.282 (5) C2---C3 1.417 (9) Mo----CI 1.947 (6) C2---C6 1.410 (9) Mo---C2 2.368 (5) C2----C7 !.481 (9) Mo--C3 2.359 (6) C3----C4 1.399 (11) Mo----C4 2.306 (6) C4--C5 1.390All the data processing was carried out on a MicroVAX 3600 computer using the NRCVAX program system (Gabe, Le Page, White & Lee, 1987).We are grateful to the National Science Council of Taiwan for financial support. Kong, Shatin, New Territories, Hong Kong. E-mail: tcwmak@cuhk.hk (Received 10 May 1995: accepted 25 August 1995 Abstract The structure of a cadmium(II) chloride adduct with an olefinic double betaine {systematic name: catena- (Chen & Mak, 1991a,b; Chen, Mak, Huang & LCi, 1992). The present report deals with the preparation and crystal structure of a cadmium chloride adduct with an olefinic double betaine that possesses pairs of cis anionic carboxylate groups and positively charged pyridinium substituents, namely catena-poly-.nH20The structure of the title adduct comprises an infinite zigzag chain plus the uncoordinated olefinic double betaine and a lattice water molecule (Fig. 1). The coordination geometry about each Cd H atom is octahedral, involving four CI ligands [Cd---C1 = 2.570 (3)-2.679 (3)~,] and two cis-related 0 atoms [Cd--O = 2.266 (8)-2.380 (7),4,], the most distorted bond angles about the three crystallographically independent cadmium(II) atoms being 86.0(2), 85.1 (1) and 82.8(2) °. Such an octahedral environment about Cd n is well documented and indeed preferred for most of the known cadmium(II) carboxylates (Prince, 1987). Unlike atoms (6) 3.228 (9), 0(5)..-O(5W) 2.629 (12) g,; see Table 3]. The configuration of the olefinic double betaine is significantly different from those in its hexahydrated form (Weiss, Roth, Lowack & Bremer, 1990) and its perchloric or nitric acid adducts (Wu & Mak, 1994a), in which two carboxylate groups are (i) twisted out of the plane of the central double bond in a conrotatory fashion, and (ii) coplanar with the central double bond, respectively. In the present adduct, one carboxylate group is almost coplanar with the dou- (Wu & Mak, 1995). Most betaine compounds are versatile ligands and exhibit strong ligation behaviour towards metals. Occurrence of the uncoordinated olefinic double betaine in the present metal complex may be due to its large steric bulk as compared with the coordinated chloro, aqua and ethanol ligands. ExperimentalThe olefinic double betaine in its hexahydrated form was synthesized-by a literature method (Weiss et al., 1990). The title adduct was prepared by dissolving CdCI2 (81.3 mg, 0.40 mmol) and the double betaine (92.8 mg, 0.20 mmol) in hot water (10ml). The resulting colourless solution was cooled and covered with ethanol (5ml). Slow diffusion at room temperature for several days yielded colourless platelike crystals. (4) t Site occupancy factors for C(19) and C(19') are 0.79 (4) and 0.21 (4), respectively, and for C(22) and C(2U) are 0.53 (2) and 0.47 (2), respectively. (20) 113 (4) O (6) (18) 12...