Aryl-linked salicylaldoxime-based copper(II) helicates and "boxes": synthesis, X-ray analysis, and anion influence on complex structure.
The synthesis and spectroscopic analysis of both "metal-only" and anion encapsulated salicylaldoxime-based complexes utilizing a new 1,3-xylyl strap are described. X-ray crystallographic analysis reveals that the aromatic spacer restricts the confirmation flexibility of the resulting complexes leading to dicopper(II) double helicate and dicopper(II) 2 + 2 "box" structural forms. The choice of the structural motif is influenced by the anion present, with the copper(II) nitrate-containing complex [NO3⊂(Cu2L(3)2)](NO3)3, 4, adopting a double helicate form, whereas the analogous copper(II) bromide complexes [2Br⊂(Cu2L(3)2)](Br)2, 5, and [2Br⊂(Cu2L(3)2)](BF4)2, 6, both adopt 2 + 2 "box" structural configurations. Spectroscopic analysis has shown an enhancement in the binding strength of ClO4(-) over the anions SO4(2-) and NO3(-). The enhanced rigidity caused by the use of the 1,3-xylyl spacer in this series of complexes has favored the formation of the "double loaded" dibromide complex.
Institute of Fundamental Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
Ajay Pal Singh
AP
Pannu
James R
JR
Stevens
Paul G
PG
Plieger
D000838:Anions / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010091:Oximes / Q000737:chemistry*
D000838:Anions; D009942:Organometallic Compounds; D010091:Oximes; C005704:salicylaldoxime; D003300:Copper