Synthesis of 4′-(4‴-benzo-15-crown-5)-methyloxy-2,2′:6′,2″-terpyridine (L) and the crystal structure of its complexes with cobalt(II) and zinc(II): [ML2](ClO4)2 · 3H2O

The synthesis of 4′-(4‴-benzo-15-crown-5)-methyloxy-2,2′:6′,2″-terpyridine (L) and is complexes with cobalt(II) and zinc(II) [CoL2](ClO4)2 · 3H2O (I) and [ZnL2](ClO4)2 · 3H2O (II) was described. For L and its complexes, the parameters of electronic absorption spectra in acetonitrile were determined and 1H NMR signals were assigned. The structures of I and II were determined by X-ray crystallography. Compounds I and II are isostructural and consist of complex cations [ML2]2+ (M = Co, Zn), ClO4− anions, and crystal water molecules. The M atoms are located in special positions on twofold axes. The M atoms are surrounded by six N atoms of the terpyridine moieties of two organic molecular ligands. The M-N distance for the N(2) atoms of the central rings of the terpyridine moieties in both structures is shorter than for the side rings. The coordination polyhedra of the M atoms can be described as severely distorted octahedra. The major distortion of the octahedra is that the N…N distances in a terpyridine moiety are considerably shorter than those between the atoms of different moieties. The maximal deviation of the terpyridine atoms from the mean-square planes through these atoms is observed for the C(2) atom: 0.103(3) and 0.106(4) Å in I and II, respectively. The Co(1) and Zn(1) atoms are at a distance of, respectively, 0.1682(14) and 0.1415(17) Å from the corresponding planes.