Structural Relationships Afforded by the Coordination of 2,2′-Bipyridine to the (Iminodiacetato)Copper(II) Chelate: Synthesis, Structure and Properties of (2,2′-Bipyridine) (N-(2-Hydroxyethyl)Iminodiacetato) Copper(II)Tetrahydrate

Abstract

The stoichiometric reaction of coppcr(1I) hydroxycarbwate, N-(2-hydroxycthyl)iminodiacctic acid [H2hcida=HOCH2CH2N(CH2C@H)J and 2.Z-bipyridine (bipy) in water yields crystalline (2.2'-bipyridinc)(N-(2-hydroxyctbyl)iminodiacetato~~r(II) tetrahydrate, [Cu@cidab (bipy)].4H20 (compound I). This was studied by TG analysis (with FT-IR study of evolved gases), IR, claaronic and ESR spectra, magnetic susocptibility data and single crystal X-ray diffraction methods. The compound .crystalliscs in the triclinic system, space group P1, u= 7.011(2), b= 12.586(3), C = 13.052(3)A, a=62.14(1), p=80.51(2), 7=77.09(2)", 2 = 2 , f i d RI = 0.051 for 3900 independent reflections. The Cu(II) atom &%its an asymmetric, clongated, octahedral coordination (type 4 + 1 + 1). and bipy acts as an Nfl-bidatate ligand sup plying two arflong the four closest donor atoms of the metal (Cu-N bond lengths of 1.994(2) and 2.053(2)A); heida plays an N,O,O',O''-tetradentatc &elating role (bond lengths Cu-N= 2.459(2)A). The cffcctive bidcutate chelation of bipy imposcsfi&clation to the iminodiaatate moiety of heida in I, as previously reported in mixed-ligand complexes having a 1 : 1 : 2 Cu(II)/IDA/N(he~yclic) or a l/l/(l + 1) Cu/IDA/(N-heterocyclic+ N-aliphatic) donor ratio. The tetradentate role of hcida in I rcvcals its noticcable conformational flexibility. The crystal 2.075(2), Cu-O(carboXy1) = 1.958(2), C~-O'(carbo~yl) = 2.337(2) and CU-O''(hydrOXy1) = Corresponding author. 235 Downloaded by [Florida Atlantic University] at 00:52 20 November 2014 236 I.S. DE LA CUEVA-TORREGROSA el al. features a hydrogcn bond network forming supra-molecular chains extending along the u axis. These arc linked by two symmetry-related hydrogen bonds of the type O(hydroxy1)-H ... O'(carboxy1) between two adjacent complex mits (symmetry code i= -x, -y + 1, --r+ I), related to each other by an inversion centre.