Spectroscopic studies of bis(2,9-dimethyl-1,10-phenanthroline)bis(pyridine)copper(I) and selected square planar platinum(II) terpyridine complexes

Toni Kay Aldridge, Purdue University

Abstract

In to better understand the principles which govern the energy of charge transfer transitions in the copper systems studied in our laboratory, the system (Cu(pyridine)$\sb4$) $\sp+$ $\to$ (Cu(dmp)$\sb2$) $\sp+$, where dmp denotes 2,9-dimethyl-1,10-phenanthroline, was studied by a least-squares algorithm, SPECDEC. The absorption data of (Cu(dmp)(py)$\sb2$) $\sp+$, which exhibits a $\lambda\sb{\rm max}$ = 442, was also characterized. We also report the absorption and luminescence of several square planar d$\sp8$ (Pt(terpy)X) $\sp{\rm n+}$, where terpy denotes the tridentate 2,2$\sp\prime$:6$\sp\prime$,2$\sp{\prime\prime}$-terpyridine ligand. For (Pt(terpy)NCS) $\sp+$, (Pt(terpy)OH) $\sp+$ and (Pt(terpy)OMe) $\sp+$ each complex exhibits relatively low-energy absorption maxima in the near UV and the visible region, well below those of the $\pi$-$\pi$* transitions of the coordinated terpy ligand, with extinction coefficients of the order of 1000M$\sp{-1}$cm$\sp{-1}$. Each of the three complexes exhibits a broad, unstructured emission in acetonitrile. The thiocyanate and hydroxide derivatives also give stable, emissive solutions and significantly enhanced emission lifetimes in methylene chloride. The methoxide, while not stable in methylene chloride, does show emissive behavior in methanol, while the hydroxide shows emission in water. The emissions of the complexes are assigned to $\sp3$d$\sb\pi$* CT excited states. To obtain additional information about these systems, we have solved the crystal structure of (Pt(terpy)OMe) BPh$\sb4$. Finally, the resemblance of vanadium(V) to phosphorous(V) in aqueous solution has generated an interest in vanadate as a phosphate analogue in biological studies. It is thought that the ability of the molecule to expand its coordination sphere may allow for the formation of complexes which resemble the transition state of phosphoryl transfer reactions in certain enzymes such as phosphoglucomutase. To gain a better understanding of the structure of the intermediate, the synthesis of mononuclear metavanadate, VO$\sb3\sp-$, in solution was attempted.

Degree

Ph.D.

Advisors

McMillin, Purdue University.

Subject Area

Chemistry

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