A new diaza-18-crown-6 ligand containing two quinolin-8-ylmethyl side arms: Crystal structures and characterization of the ligand, the protonated ligand and its mononuclear barium(II) and dinuclear copper(II) complexes

✍ Scribed by N. Kent Dalley; Guoping Xue; Jerald S. Bradshaw; Xian Xin Zhang; Roger G. Harrison; Paul B. Savage; Krzysztof E. Krakowiak; Reed M. Izatt

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2001
• Tongue: English
• Weight: 169 KB
• Volume: 38
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570380101

✦ Synopsis

A new 7,16-bis(quinolin-8-ylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane ligand, L, has been prepared and its crystal structure reported. In addition, the structure of the protonated ligand H 2 L has been determined. H 2 L is of interest because of interatomic interactions between the ligand and perchlorate ions. The mononuclear Ba(II) (BaL), and dinuclear Cu(II) (Cu 2 L) complexes of L have been prepared and their crystal structures determined. Stability constants and other thermodynamic data valid in methanol at 23 or 25°f or these and several other complexes of L have been obtained. Among the metal ions studied, L forms the most stable complex with Ba 2+ . In addition, L selectively binds Cu 2+ over Ni 2+ by about 3 orders of magnitude. Some of the complexes have been studied using nmr and uv-vis spectroscopic techniques. Crystal data are given for L, space group, P2 1 /c, a = 8.8325( 14) Å, b = 13.808(3) Å, c = 13.310(3) Å; β = 94.72(2)°Z=2, R = 0.0727; for H 2 L, space group, P2 1 /c, a = 14.685(3) Å, b = 15.035(6) Å, c = 17.369(4) Å, β = 90.366(12)°, Z = 4, R = 0.0781; for BaL, space group, Pbcn, a = 17.314(3) Å, b = 9.539(2) Å, c = 22.081(3) Å, Z = 4, R = 0.0354; and for Cu 2 L, space group, Cc, a = 19.762(2) Å, b = 14.413(2) Å, c = 14.935(2) Å, β = 98.753( 12)°, Z = 4, R = 0.0564. Cu 2+ forms a hydroxo-bridged dinuclear complex with L while Ba 2+ forms a mononuclear complex with L in which its two side arms are not involved in complexation.