Flexible Disulfoxides as Bridging Ligands for Copper(II) Coordination Architectures: Fine Tuning the Complex Structures by Ligand Modifications

Ten disulfoxide−CuII coordination architectures, {[Cu(meso-Lb)2(ClO4)](ClO4)}n (1B), [Cu(meso-Lb)2(ClO4)2]n (2B), [Cu(rac-Lb)2(ClO4)2]n (3B), {[Cu(meso-Lb3)3](ClO4)2}n (3B‘), [Cu(meso-Lc1)2(ClO4)2]n (1C), [Cu(meso-Lc2)2(ClO4)]2(ClO4)2(CHCl3)2 (2C), {[Cu(meso-Lc3)2(ClO4)](ClO4)}n (3C), [Cu(meso-Ld1)2(ClO4)2]n (1D), {[Cu2(rac-Ld2)4(ClO4)2](ClO4)2(CHCl3)}n (2D), and [Cu(rac-Ld3)2(ClO4)2]n (3D), were obtained by the reaction of Cu(ClO4)2 with
nine structurally related flexible disulfoxide ligands, RS(O)(CH2)nS(O)R (n = 2−4; R = −CH2CH3, −CH2CH2CH3,
−CH2CH2CH2CH3 for Lbn-1, Lcn-1, and Ldn-1, respectively) in the presence of dehydrating reagent (diethoxyethane)
in acetone/chloroform. The X-ray crystal structural analyses of the complexes revealed that all of them display a
2-D network structure, except for 2B and 2C, which display a one-dimensional and a dinuclear cage structure,
respectively. All 2-D systems have a (4,4) topological arrangement with different conformations, except for 3B‘,
which has a (3,6) structure. It is noteworthy that complexes 3B and 3B‘, with different structures, are obtained in
the same reaction system, being a relatively rare case. In all of the complexes the ligands react in the bis-monodentate
coordination mode, acting as linkage bridges:  this feature is important for the assembly of the polymeric complexes.
In addition, the configuration inversion of some disulfoxide ligands has been observed when reacting with CuII ions.
In combination with other reported disulfoxide−CuII complexes, a systematic structural comparison was performed
so as to summarize some general relationships among the spacer lengths, terminal groups of related ligands, and
structures of the complexes. The magnetic behavior of three complexes, 1B−3B, as examples, was investigated.