Sheila M. Morehouse

The structure and electrochemistry of imidazolebis(1-10 phenanthroline)copper(II) nitrate

Abstract [Cu(phen) 2 (imidazole)](NO 3 ) 2 crystallizes in the triclinic space group P 1(No.2) with a =8.807(2), b =8.941(4), c =17.135(4) A, α =100.95(2), β =90.95(1), γ =100.187(9)°, and Z =2. The structure consists of discrete [Cu(phen) 2 (imidazole)] 2+ ions with a distorted square pyramidal geometry about the copper. One of the cis -phenanthroline ligands is asymmetrically coordinated to the axial (CuN phen =2.225(6) A) and equatorial (CuN phen =2.050(5) A) sites, while the second phenanthroline (CuN phen =2.027(5) A and CuN phen =2.021(5) A) and the imidazole (CuN im =1.980(6) A), occupy the remaining equatorial sites. The reversible one electron reduction potential of [Cu(phen) 2 (imidazole)] 2+ , ( E 1/2 =0.10 V) in methanol, is more negative than that observed for [Cu(phen) 2 ](NO 3 ) 2 , ( E 1/2 =0.16 V). The relationship between the structure of [Cu(phen) 2 (imidazole)](NO 3 ) 2 and the corresponding dimer [Cu 2 (phen) 4 (imidazolate)](NO 3 ) 3 is discussed, and the electrochemistry is compared to the negative shift in redox potential which is observed when the nuclease [Cu(phen) 2 ] 2+ binds to CT DNA.

The crystal and molecular structure of μ-imidazolatobis [bis (1–10 phenanthroline)copper(II)] nitrate

Abstract [Cu2(phen)4(im)](NO3)3·3H2O·2CH3OH crystallizes in the triclinic space group P 1 (#2) with a = 13.803(10) A , b = 16.844(8) A , c = 13.395(9) A , α = 111.1(2)°, β = 116.8(1)°, γ = 89.6(1)° and Z = 2 . The structure consists of the dimeric [Cu2(phen)4(im)]+3 ion with the imidazolate ion bridging the two Cu(phen)2 moieties. The lattice contains three water molecules and two methanol molecules of solvation as well as the nitrate anions. The two [CuN4(im)] chromophores are distorted square pyramidal with one of the cis phenanthroline ligands asymmetrically coordinated to the axial (Cu-Nphen = 2.232(9) A and 2.24(1) A) and equatorial (Cu-Nphen = 2.016(9) A and 2.020(9) A) sites. The remaining equatorial sites are occupied by the second phen ligand on each Cu and the bridging imidazolate ion. The relationship between the structure and the antiferromagnetic behavior of the cation is discussed.