Phenanthroline complexes of the d10 metals nickel(0), zinc(II) and silver(I)—comparison to copper(I) species

Structural features and physical properties of dmphen (2,9-dimethyl-1,10-phenanthroline) complexes with d10 metals ZnII, Ni0 and AgI were determined. These, together with the more well-known CuI compounds, constitute a rare example of an Ni0, CuI, ZnII isoelectric, isostructural series. The first homoleptic zinc dmphen compounds [ZnNO3(dmphen)2]NO3 (1) and Zn(dmphen)2(BF4)2 (2) were prepared. Their structures were determined by X-ray crystallography. Compound 1 is five-coordinate, with one nitrate ion coordinated. Compound 2, of the same stoichiometry as 1, exhibits the pseudotetrahedral, four-coordinate Zn(dmphen)22+ cation, which is isoelectronic and isostructural with the more well known Cu(dmphen)2+ cation. Ni(dmphen)2 (4) was prepared for the first time. Reaction of Ni0(cyclooctadiene)2 with dmphen in ethanol or tetrahydrofuran gave crystals of dark blue Ni0(dmphen)2 (4). NMR experiments show that 4 is diamagnetic, with chemically equivalent dmphen ligands. From this species, by reaction with dichloromethane, Ni2(dmphen)2Cl4 (5) was obtained. In this compound each nickel atom bears one terminal chloride ligand and the two nickel atoms are connected by two μ-chlorine atoms. Finally, Ag(dmphen)2BF4 (6) was prepared, which now extends the isostructural series described above to a second-row transition metal. The structure of this compound was determined by X-ray crystallography.