Other Tetradentate Crown Thioethers

In the series [Cu(nS4)] (n = 12-16) plus [Cu(2,5-dithiahexane)2] Cu-S distances increase systematically. This trend reflects the conformational mobility associated with successive replacement of by propyl linkages [89]. 

In [CuCl((MeO)8benz04-12S4)] [190] (Table 1) four sulfur atoms from the ligand form the base of a square pyramidal coordination sphere that is capped by an apical Cl ion. Two mutually cis S atoms bind more strongly than do the other two, as reflected in the Cu-S distances (which differ by 0.2 A). Doming of the CUS4CI coordination sphere places the Cu ion 0.121 A above the S4 basal plane. 

Two of the four phenylene units lie approximately in the idealized S4 plane, while the other two lie below it, on the side opposite the Cu ion. 

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