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Synthesis, Structure and Solution Chemistry of (5, 5′‐Dimethyl‐2, 2′‐bipyridine)(IDA)copper(II) and Structural Comparison With Aqua(IDA)(1, 10‐phenanthroline)copper(II) (IDA = iminodiacetato)
Author(s) -
Craven Emma,
Zhang Cungen,
Janiak Christoph,
Rheinwald Gerd,
Lang Heinrich
Publication year - 2003
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200300223
Subject(s) - chemistry , copper , potentiometric titration , stacking , hydrogen bond , crystallography , molecule , crystal structure , inorganic chemistry , 2,2' bipyridine , chelation , ligand (biochemistry) , titration , phenanthroline , organic chemistry , ion , biochemistry , receptor
The protolytic equilibria of copper(II), 5, 5′‐dimethyl‐2, 2′‐bipyridine (bpy) and iminodiacetate (IDA) have been investigated by potentiometric titration between pH 2 and 8. Potentiometric titration suggests the presence of [Cu(IDA)(bpy)] 0 at a fraction of 28 % of all copper species in solution at pH 8 with a stability constant log β = 13.9. The crystal structures of [Cu(IDA)(bpy)] · 4H 2 O ( 1 ) and [Cu(IDA)(H 2 O)(phen)] · 4H 2 O ( 2 ) show the IDA ligand coordinated in the fac ‐NO+O mode. The structure of 1 features “dimeric” entities of symmetry‐independent five‐coordinated Cu‐complexes through a long Cu···O contact, hydrogen bonding and π‐stacking, including a “pyridyl—metal‐chelate ring” π‐contact as evidence for metalloaromaticity in aromatic α, α′‐diimine‐copper(II) chelates. The structure of 2 has the tetragonally six‐coordinated molecular Cu‐complexes arranged by hydrogen bonding and π‐stacking. The crystal water in 2 forms infinite corrugated double chains composed of alternating four‐ and six‐membered, edge‐sharing rings of hydrogen‐bonded water molecules.