Three-Dimensional Cadmium(II) Cyanide Coordination Polymers with Ethoxy-, Butoxy- and Hexyloxy-ethanol

Abstract

Abstract:The three novel cadmium(II) cyanide coordination polymers with alkoxyethanols, [Cd(CN) 2 (C 2 H 5 OCH 2 CH 2 OH)] n (I), [{Cd(CN) 2 (C 4 H 9 OCH 2 CH 2 OH)} 3 {Cd(CN) 2 }] n (II) and [{Cd(CN) 2 (H 2 O) 2 }{Cd(CN) 2 } 3 ·2(C 6 H 13 OCH 2 CH 2 OH)] n (III), were synthesized and charcterized by structural determination. Three complexes have three-dimensional Cd(CN) 2 frameworks; I has distorted tridymite-like structure, and, II and III have zeolite-like structures. The cavities of Cd(CN) 2 frameworks of the complexes are occupied by the alkoxyethanol molecules. In I and II, hydroxyl oxygen atoms of alkoxyethanol molecules coordinate to the Cd(II) ions, and the Cd(II) ions exhibit slightly distort trigonal-bipyramidal coordination geometry. In II, there is also tetrahedral Cd(II) ion which is coordinated by only the four cyanides. The hydroxyl oxygen atoms of alkoxyethanol connects etheric oxygen atoms of the neighboring alkoxyethanol by hydrogen bond in I and II. In III, hexyloxyethanol molecules do not coordinate to the Cd(II) ions, and two water molecules coordnate to the octahedral Cd(II) ions. The framework in III contains octahedral Cd(II) and tetrahedral Cd(II) in a 1:3 ratio. The Cd(CN) 2 framework structures depended on the difference of alkyl chain for alkoxyethanol molecules.

Synthesis and Crystal Structures of Cadmium(II) Cyanide with Branched-Butoxyethanol

“…The Cd2-O1 bond length is slightly longer than the Cd TB -O bond lengths of complexes [Cd(CN) 2 (Etcel)] n and [{Cd(CN) 2 (Bucel)} 3 {Cd(CN) 2 }] n [22]. The tBucel ligand on Cd2 is connected with the neighboring tBucel on Cd2 by hydrogen bonds between one ligand's hydroxyl oxygen atom O1 and the other's etheric oxygen atom O2 (Figure 2c and [22], and I. Around the Cd3, two oxygen (O3) atoms are located at the axial positions and four cyanides are located at the equatorial positions.…”

“…The iBucel molecules exist as both a ligand and a guest in the Cd(CN) 2 cavities (Figure 1a and Figure S1c). Because all iBucel molecules are strongly disordered (Figure 1a), the R factor is relatively high (Table 1) [22].…”

“…Symmetry codes: i = −x, y, −z + 1/2; iv = −x + 1/2, −y + 1/2, −z + 2; vi = −x + 1/2, −y + 1/2, −z + 1. (Figures 1d and 2c) [22]. The (O-CH 2 -CH 2 -O) 2 eight-membered rings may assist in the coordination of alkoxyethanol molecules to Cd(II) ions and in the stabilization of that coordination.…”

“…Single crystals of complexes I and II were prepared by a method similar to that found in the literature [4,22]. Crystal data for I and II are listed in Table 1.…”

“…The five-coordination geometry is estimated by a simple distortion parameter τ proposed by Addison et al [22,35,36]. The τ value is simply defined by τ = (θ 1 − θ 2 )/60, where θ 1 is the largest basal angle and θ 2 is a second largest; a perfect square pyramid is characterized by τ = 0, while τ = 1 represents a perfect trigonal bipyramid [22,35,36]. For the Cd2, τ is 0.46 from the selected bond angles, as shown in Table 3.…”