Differences in Nuclearity, Molecular Shapes, and Coordination Modes of Azide in the Complexes of Cd(II) and Hg(II) with a 'Metalloligand' [CuL] (H2L = N,N′-Bis(salicylidene)-1,3-propanediamine): Characterization in Solid and in Solutions, and Theoretical Calculations

Two new heterometallic copper(II)–mercury(II) complexes [(CuL)Hg(N3)2]n (1) and [(CuL)2Hg(N3)2] (2) and one copper(II)–cadmium(II) complex [(CuL)2Cd(N3)2] (3) have been synthesized using “metalloligand” [CuL] (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine) and structurally characterized. Complex 1 is a one-dimensional (1D) helical coordination polymer constructed by the joining of the dinuclear [(CuL)Hg(N3)2] units through a single μ-l,l azido bridge. In the dinuclear unit the Hg(II) is bonded with two phenoxido oxygen atoms of “metalloligand” [CuL] and two nitrogen atoms of azido ligands. Complex 2 is a linear trinuclear entity, in which two terminal “metalloligands” [CuL] are coordinated to central Hg(II) through double phenoxido bridges. The azido ligands link the central mercury atom with the terminal copper atoms via μ-l,3 bridges. In contrast, the trinuclear complex 3 is bent. Here, in addition to two double phenoxido bridges, central Cd(II) is bonded to two mutually cis nitrogen atoms of tw...