Azido-bridged Cu(II) compounds with asymmetric end-to-end and end-on binding modes: magnetic assignments using a spin dimer model

Dinuclear [Cu(aepi)(N3)2]2 (1) [aepi = 1-(2-aminoethyl)piperidine] and 1D chain [Cu(aepy)(N3)2]n (2) [aepy = 1-(2-aminoethyl)pyrrolidine] have been prepared and characterized by means of X-ray analysis and magnetic measurements. For 1, the Cu(II) centers are doubly bridged by end-on (EO) azido units in a basal-apical fashion. The molecular structure of 2 features magnetic centers that are linked by μ-1,1,3 azido groups, forming a 1D chain with alternating EO and end-to-end (EE) azido bridging patterns. Magnetic data for 1 and 2 reveal that ferromagnetic and antiferromagnetic interactions are mediated through EE and EO azido bridges, respectively. These assignments are also confirmed by MO calculations using spin dimer model.