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)

Abstract

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 logβ = 13.9. The crystal structures of [Cu(IDA)(bpy)] · 4H2O (1) and [Cu(IDA)(H2O)(phen)] · 4H2O (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.

The π‐Back‐Bonding Modulation and Its Impact in the Electronic Properties of CuII Antineoplastic Compounds: An Experimental and Theoretical Study

“…[c] p K a value obtained from ref. 45. [d] p K a calculated obtained employing σ values reported in ref.…”

Very Strong Parallel Interactions Between Two Saturated Acyclic Groups Closed with Intramolecular Hydrogen Bonds Forming Hydrogen-Bridged Rings

“…The data in Figure 3 show that most of the parallel contacts have the normal distances between 3.0 and 3.5 Å. These are distances typical for stacking of organic aromatic rings (3-4 Å) [17][18][19][20][21][22] and other planar rings that form stacking interactions [24][25][26][27][43][44][45][46]. The data in Figure 3 show that most of the parallel contacts have the normal distances between 3.0 and 3.5 Å.…”

Dinuclear Nickel(II) and Palladium(II) Complexes in Combination with Different Co-Catalysts as Highly Active Catalysts for the Vinyl/Addition Polymerization of Norbornene

“…This corresponds to a vertical displacement between the ring centroids of 1.27Å (centroid separation 3.78Å, interplanar distance 3.55 or 3.58Å, respectively). In comparison, these intermolecular π-stackings exhibit rather short centroid-centroid contacts (< 3.8Å), small slip angles (< 25 • ) and vertical displacements (< 1.5Å) which translate into a sizable overlap of the pyridylplane areas [85].…”