J. Am. Chem. Soc., 127 (43), 14978 -14979, 2005. 10.1021/ja054906m S0002-7863(05)04906-1
Web Release Date: October 8, 2005

Copyright © 2005 American Chemical Society

Luminescence from the trans-Dioxotechnetium(V) Chromophore

Andrew S. Del Negro, Zheming Wang, Carl J. Seliskar, William R. Heineman, B. Patrick Sullivan, Sean E. Hightower, Timothy L. Hubler,* and Samuel A. Bryan*

Pacific Northwest National Laboratory, Richland, Washington 99352, University of Cincinnati, Cincinnati, Ohio 45221, and University of Wyoming, Laramie, Wyoming 82071

tim.hubler@pnl.gov; sam.bryan@pnl.gov

Received July 21, 2005

Abstract:

The luminescence of trans-[TcO2(L)4]+ (L = pyridine (py) or picoline (pic)) and trans-[TcO2(CN)4]3- at room and low temperature is described and represents the first example of room temperature excited-state luminescence observed for Tc complexes. At room temperature, the complexes exhibited broad luminescence with emission maxima ranging from 745 to 780 nm. Analogous to the Re complexes (emission at 635-655 nm), the low-temperature emission spectra of microcrystalline samples of [TcO2(py)4]BPh4 and [TcO2(pic)4]BPh4 display the characteristic progressions of the symmetric O=Tc=O and Tc-L stretching modes. DFT/TDDFT calculations were performed on the trans-[MO2(L)4]+ (M = Re, Tc) congeners and predicted the dioxotechnetium emission to be 0.41 eV lower in energy than its Re analogue. Low-temperature lifetimes (8 K) ranging from 15 to 1926 s for the series of Tc complexes are consistent with the Re analogues.

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