Structural Change of a Linear Polyether upon Complex Formation. l.ll-Bis(2-acetylaminophenoxy)-3.6.9-trioxaundecane and its KSCN Complex"

The title compound (1) was crystallized as free ligand and as its (1 • KSCN)2 • H 2 0 complex. Crystallographic data are, for the former: space group C 2/c, a — 31.110(9), b = 4.608(4), c = 17.188(6) A, ß = 105.27(8)°, Z = 2, Dm = 1.25 gem-3 ; for the latter: space group P2i, a = 11.044(3), b = 18.310(4), c = 14.485(4) Ä, ß = 97.49(2)°, Z = 4, Dm = 1.27 gem -3 . Crystal structures were solved by direct methods using X-ray diffraktometer data and least squares refinements converged at 10.8% for 1 and at 7.6% for (1 • KSCN)2 • H 2 0 . The free ligand (1) is S-shaped and, upon K+-complexation, changes signs of some gauche O-C-C-O torsion angles while C-C-O-C angles remain trans. In (1 • KSCN)2 • H 2 0 , there are two complex molecules 1 A • KSCN • H 2 0 (I) and 1 B • KSCN (II). The ligands are wrapped circularly around K + and coordinated with only four of the five polyether oxygens. K+ interacts further with H 2 0 in (I) and with N of SCN~ in II and, in both complexes, with acetylamino oxygen of adjacent 1. The latter interaction leads to polymeric structures not observed previously for similar complexes.