POLYMERIC AND MIXED CARBOXYLATE COMPOUNDS - CRYSTAL-STRUCTURES OF [ZN(TIGLATE)2]X AND [ZN2(TIGLATE)3(CROTONATE)]X

The crystal structures of [Zn(O2CC(CH3)CHCH3)2]x and [Zn2(O2CC(CH3)CHCH3)3-(O2CCHCHCH3)]x have been determined by single crystal X-ray diffraction. Both structures consist of chain polymers, in which pairs of zinc atoms are bridged alternately by three syn-syn carboxylates and by one syn-anti carboxylate. In the mixed carboxylate structure, the crotonate takes up preferentially the syn-anti bridge position. Vibrational and elemental analysis data indicate that the spontaneous solid-state reaction of zinc tiglate in air, accelerated for the tiglate and observable also for the mixed carboxylate compound by gamma-ray or X-ray irradiation, gives an oxo-centered tetranuclear complex [Zn4O(O2CR)6] rather than a polymerization through cross-linking of the unsaturated carboxylates.