STUDIES ON THE MOLECULAR-MOTION OF [M(DACO)2]2-DACO COMPLEXES OF MX2 (M=CU(II) AND NI(II) AND X=CLO4 OR NO3, DACO=1,5-DIAZACYCLOOCTANE)( IONS IN BIS)

The temperature dependence of the second moment (M2) of H-1 NMR absorp tion of the partially deuterated (deuterated amine protons) complexes [M (daco-d2)2] X2 . n D2O (M = Cu(II) and Ni(II); daco = 1,5-diazacycl ooctane; X = ClO4 or NO3; n = 0 for X = NO3 and n = 2 for X = ClO4) ha s been measured. Among them, [Cu(daco-d2)2](NO3)2 showed a distinct dr op in M2 at the same temperature region (ca. 363 K) where the complex is reported to undergo the thermochromic phase transition. The complex es [Cu(daco-d2)2](ClO4)2.2D2O and [Ni(daco-d2)2](ClO4)2.2D2O showed a gradual decrease of M2 around 220 and 280 K, respectively, without any colour changes and phase transitions, whilst M2 of [Ni(daco-d2)2](NO3 )2 shows no marked decrease with increase of temperature up to 400 K. M2 of rigid and motional lattices of [Cu (daco-d2)2](NO3)2 is theoreti cally calculated using the reported X-ray crystal structure data. The molecular motions of [Cu(daco-d2)2](NO3)2, [Cu(daco-d2)2](ClO4)2.2D2O and [Ni(daco-d2)2](ClO4)2.2D2O are explained in terms of dynamic disor der of metal diamine chelate rings.