Study of the thermal decomposition processes of clathrate compounds

Abstract

The decompositions of the clathrate compounds [M(NCS)2(4-MePy)4 ]"nG (where M = Mn, Co, Ni or Cd; G = 4-methylpyfidine (4-MePy), benzene or xylenes) were studied on a Q-derivatograph under quasi-equilitlrium conditions and with linear heating. These clathrates can be divided into two groups, in which the loss of guest is either (I) accompanied by destruction of the host complex, or (II) occurs before decomposition of the host complex. Kinetic parameters were obtained.Due to their structures clathrate compounds are interesting subjects for the research of heterogeneous thermal reactions of the type As -* Bs + CgasIn this work we have studied the features of the decompositions of the clathrate compounds M(NCS)2(4-MePy)4nG, where M = Mn(II), Co(II), Ni(II) or Cd(II), and G ---= 4-methylpyridine (4-MePy), benzene or xylenes. ExperimentalSynthesis of the host coordination complexes was carried out by a known method [1]. The clathrate compounds were sysnthesized through the reaction between the host coordination complex (crystal compound) and the guest in the vapour state at room temperature.The thermal decomposition processes were studied on a Q-derivatograph under quasi-equilibrium conditions [2] using different sample holders and with linear heating. The temperatures of decomposition under quasi-equilibrium conditions were used for qualitative estimation of the thermodynamic stabilities of the compounds investigated.The kinetic curves of gas evolution were obtained by means of a continuous reactor [3] under non-isothermal conditions. The samples had a mass of 5-10 rag; the heating rate was 4-6 deg min -1 ; the helium flow rate was 60 cm a min -1 ; a conductometric detector was used. Experimental data were processed on a computer with the program TA IB [4]. For the compounds studied, the equation of a contracting sphere was the equation best describing the process. The values of E and A were calculated from 5 experiments; experimental errors were found with a confidence level of 95%.

Thermal decomposition reactions of nickel(II) complexes under quasi-equilibrium conditions

“…It was proved ( Table 3) that the decomposition of the clathrate at room temperature proceeds wholly to the 13-phase without essential change of structure (a --prepared by reaction (10) This is in accordance with papers [9,10] in which analogical clathrate 13-[Ni(4-Mepy)a(NCS)2]. (4-Mepy) was studied.…”