**2. Coordination compounds based on the aromatic isocyanates and copper (II) chloride for the synthesis of polyurethanes**

In the early studies (Davletbaeva et al., 1998) devoted to imparting special properties to polyurethanes by their coordination bonding, it was shown that the interaction of aromatic isocyanates with copper chloride (CuCl2) in the acetone medium in the presence of trace amounts of water proceeded as a sequence of chemical transformations including simple addition and decomposition reactions, redox processes, and subsequent complexation (Fig. 1).

The ultimate products are polynuclear complexes of azoaromatic compounds, in which copper ions occurring in two variable oxidation states are connected by chloride bridges (Fig. 1). As it is seen from the structural formulas, some copper ions are stabilized at the initial degree of oxidation due to the formation of heterovalent pairs connected by сhloride bridges. Free isocyanate groups present in these compounds are able to react with oligodiols of different nature. Polyurethanes obtained in such manner form polymer network by coordination bonding of urethane groups and azogroups which are the part of a macrochain.

It is shown that the chloride bridges are replaced by heteroatoms that are present in polymer chains while metal ions are coordinatively bound to macromolecules to crosslink them and, occurring in two interacting variable oxidation states, to form local centers of exchange interactions. As a result of electron transfer from one local coordinated unit to another, which is mediated by electron-donating groups, such as an ester group, the conductivity of polyurethane increases by several orders of magnitude.
