Polynuclear Zinc(ii) Complexes With Large Polyazacycloalkanes - Equilibrium Studies and Crystal-structure of the Binuclear [zn2([30]anen10)(ncs)](clo4)3 Complex

Large polyazacycloalkanes, defined as saturated aza macrocycles with more than six secondary nitrogens as donor atoms, are interesting ligand molecules. The cyclic nature, the elevated number of donor atoms available, and the molecular flexibility make these ligands very versatile for the formation of polynuclear metal complexes. In earlier papers we have reported the synthesis and the copper(I1) complexes of many large polya z a c y ~ l o a l k a n e s . ~I-n~ this paper we have investigated the formation equilibria of binuclear zinc(I1) complexes of the three large polyazacycloalkanes 1,4,7,10,13,16,19,22,25-nonaazacycloheptacosane ( [27]aneN9), 1,4,7,10,13,16,19,22,25,28-decaazacyclotriacontane ( [30]aneNlo),a nd 1,4,7,10,13,16,19,22,25,2l8-u,n3 - decazacyclotritriacontane ( [33]aneN11.