Complexes of 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene with cobalt(II), nickel(II), and copper(II); X-ray structure determination of di-isothiocyanato(2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene)nickel(II)

Abstract

The preparations and properties of a number of complexes of Co^II Ni^II and Cu^II with 2,4,4-trimethyl-1,5,9-tri-azacyclododec-1-ene, L, are reported. Reaction of bis(4-azaheptane-1,7-diamine)metal(II) complexes as their thiocyanate and perchlorate salts with acetone yields the products [ML(NCS)₂] or [(ML)(OH)₂][ClO₄]₂ respectively. With Ni^II, and to a lesser extent Cu^II the di-µ-hydroxo-dimer reacts with organic acids which form chelating anions to yield complexes [ML(X)]A (X = pentane-2,4-dionato, acetate, µ-oxalato, or 2-acetylphenolato; A = unco-ordinated perchlorate or thiocyanate ion). The complexes are five co-ordinate, except for [{NiL(NCS)}₂C₂O₄] and [NiL(pd)(NCS)]. The structure of [NiL(NCS)₂] has been determined by X-ray diffraction [space group Pbca, a= 18.060(5), b= 14.392(2), _c= 14.224(2)ÅR= 0.068, R′ 0.057 for 1 126 reflections] and shows a distorted square-pyramidal arrangement about the nickel ion with a methyl group in the ‘vacant’ octahedral site, 2.92 Å from the metal. d–d Spectra, i.r. spectra, and room-temperature magnetic susceptibilities are reported. The complexes [(NiL)₂(OH)₂][ClO₄]₂ and [CuL(pd)][ClO₄]₂ obey the Curie-Weiss law over the range 100–300 K, while [(CuL)₂(OH)₂][ClO₄]₂ shows appreciable antiferromagnetic spin coupling over this temperature range (2J=–120 cm^–1).