Tridentate N-3 capping coordination behaviour of potentially multi-site coordinating cyclotriphosphazenes: synthesis and spectroscopic studies of 2,2-spiro(1,3-propanediamino)-4,4,6,6-tetrakis(3,5-dimethylpyrazolyl)cyclotriphosphazene, 2,2-diamino-4,4,6,6-tetrakis(3,5-dimethylpyrazolyl)-cyclotriphosphazene and their mononuclear complexes; X-ray structure of ATPCTP center dot CoCl2

Two new potentially multi-site coordinating cyclophosphazenes, gem-N3P3[HN( CH2)(3)NH](3,5-Me(2)Pz)(4) (STPCTP) and gem-N3P3(NH2)(2)(3,5-Me(2)Pz)(4) (A TPCTP) have been synthesised and characterised. These form mononuclear comp lexes with Cu(II), Co(II) and Ni(II) halides which have been studied by opt ical spectroscopy. An X-ray analysis of ATPCTP . CoCl2 shows the Co(II) ato m to exist in a distorted trigonal bipyramidal geometry in which the two ch loride atoms and a nitrogen atom of the cyclophosphazene ring form the equa torial plane; the axial positions are occupied by nitrogen atoms derived fr om the two non-geminal pyrazolyl substituents. The amino substituents on th e cyclophosphazene ring do not take part in coordination. (C) 1999 Elsevier Science S.A. All rights reserved.