ChemInform Abstract: Intramolecular Coordination of Bidentate Lewis Bases to a Cofacial Binuclear Copper(II) Complex.

Abstract

304ChemInform Abstract A new bis(β-diketone) ligand is synthesized by alkylation of the 2,4-pentanedionate ion by 2,7-bis(bromomethyl)naphthalene and converted to (I) by treatment with aqueous (Cu(NH3)4)2+. (I) crystallizes as solvate with two mol of CHCl3 in the space group C2/c with Z=4. CHCl3 is associated to the diketonate group of the complex by weak hydrogen bonding. Equilibrium constants for binding of theLewis base ligands Py, quinuclidine, pyridazine and diazabicyclooctane to (I) in CHCl3 at 20 rc C are given. The oordination mode of one of these is demonstrated by a crystal structure analysis of the complex (II) (space group Pnma, Z=4). Experimental and theoretical treatments of (II) indicate that rotation of the bond ligand is rapid at room temp.; also, thermodynamic data for inding o f diazabicyclooctane to (I), a relatively rigid transition-metal host, are similar to those expected if the guest molecule retains one normal degree of freedom.