INTERACTIONS BETWEEN CETYLTRIMETHYLAMMONIUM OR TETRAMETYLAMMMONIUM BROMIDE AND MCl2 OR MCl5 (M = Hg, Cu, Zn, Co, Ni, Cd and Nb) IN MONONUCLEAR COMPLEXES: SYNTHESIS AND INFRARED STUDY

Abstract: On allowing cetyltrimethyl ammonium bromide (C19H42NBr) and HgCl2, CuCl2.2H2O, CoCl2.6H2O, ZnCl2, NiCl2.6H2O or NbCl5 in specific ratio in methanol, new mononuclear have been obtained and studied by infrared. The suggested structures are discrete, of infinite chain with octahedral or tetrahedral environments around the metallic centres. The MX2 behaves as discrete chains. For most of the structures, when intermolecular hydrogen bonds are considered, supramolecular architectures may be obtained.

In this dynamic, we have initiated in this work the study of the interactions between cetyltrimethyl ammonium bromide (CTAB) and some MCl2 molecules. This has yielded ten new adducts whose infrared study has been carried out then structures suggested based on infrared data.
The mixtures were stirred around two hours before being submitted to a slow solvent evaporation.
The analytical data [% calculated (% found)], have allowed to suggest the following formulae (Table 1). Infrared spectra were recorded on a Bruker Vector 22 spectrometer equipped with a Specac Golden Gate TM ATR device. Infrared data are given in cm -1 [IR abbreviations: (vs) very strong, (s) strong, (m) medium, (vw) very weak].
Elemental analyses were performed at the "Institut de Chimie Moléculaire", University of Bourgundy, Dijon (France). All chemicals were purchased from Sigma-Aldrich Chemie GmbH, Steinheim, Germany and used without any further purification.  A and tetrabutyl ammonium for B), a discrete monomeric structure (Fig. 1a) with an Hg II centre linked to three bromides, the environment around the metallic centre being trigonal. A dimer, with two internal bridging bromides and two external ones on each mercury centre, have also been suggested (Figure 1b).  -For C and D while considering the complex-anion [CoCl3Br] 2or [CoBr3Cl] 2-, a discrete structure with a metallic centre bonded to three chlorine atoms and one bromine atom or, to three bromine atoms and one chlorine atom, in a tetrahedral manner (Figure 2). -For E while considering the complex-anion [NiBr3(H2O)3] -, a discrete structure in which the Ni II centre is linked to three bromides and three water molecules to complete the octahedral arrangement around the nickel centre, the remaining water molecules being lattice Figure 3. -For F, a two metallic components: the first one being the molecule CuCl2(H2O)4 whose metallic centre is in the middle of an octahedron, the second one being the complex-anion [CuCl4(H2O)2] 2deriving from the previous molecule by replacing two water molecules with two chlorides (Figure 4).

Compounds obtained with MX3 moiety
Let us consider the main IR data (Table 3) of compounds G-I. It is noteworthy to outline that in these compounds the starting material NbCl5, in its interactions with the CTAB turn into NbCl3O or into NbBr3O. From these infrared data we suggest: -For G, and H a discrete structure consisting of a NbX3O (X = Cl or Br) molecule on which two water molecules come set, the metallic centre being seven coordinated (Fig. 5). -For I a discrete structure coming the previous one by removing one water molecule, the Nb centre being six coordinated ( Figure 6).

CONCLUSION
With the CTAB cation we have been able to obtain simple structures with complex tetrahedral or octahedral ions. The transformation of NbCl5 in NbCl3O or NbBr3O was found in the study of interactions involving NbCl5.