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Ground and Excited States of [M(H₂timdt)₂] Neutral Dithiolenes (M = Ni, Pd, Pt; H₂timdt = Monoanion of Imidazolidine-2,4,5-trithione): Description within TDDFT and Scalar Relativistic (ZORA) Approaches

Pina Romaniello,^† M. C. Aragoni,^‡ M. Arca,^‡ T. Cassano,^§ C. Denotti,^‡ F. A. Devillanova,^‡ F. Isaia,^‡ Francesco Lelj,*^† V. Lippolis,^‡ and R. Tommasi^§

LAMI Dipartimento di Chimica and LASCAMM-INSTM Sezione Basilicata, Universitá della Basilicata, Via N. Sauro, 85100 Potenza, Italy, Dipartimento di Chimica Inorganica ed Analitica, S.S. 554 Bivio per Sestu, 09042 Monserrato-Cagliari, Italy, and Dipartimento di Fisica, Via G. Amendola 173, 1-70126 Bari, Italy

J. Phys. Chem. A, 2003, 107 (45), pp 9679–9687

DOI: 10.1021/jp034758r

Publication Date (Web): October 17, 2003

†

Universitá della Basilicata.

‡

Dipartimento di Chimica Inorganica ed Analitica.

Dipartimento di Fisica.

To whom correspondence should be addressed. E-mail: lelj@unibas.it.

Abstract

Nonrelativistic and relativistic time-dependent density functional calculations have been performed on the excited states of the [M(H₂timdt)₂] (M = Ni, Pd, Pt) compounds. These complexes are characterized by an absorption at about λ = 1000 nm of rarely encountered intensity (ε ≈ 8000 M^-1 cm^-1) compared to those of similar compounds, attributed to a π → π* electronic transition between the HOMO and the LUMO. The comparison of the calculated spectra with the experimental data allows a possible assignment of the spectra. Our results confirm that, in all members of the series, the excited state at the lowest energy corresponds to a HOMO → LUMO excitation and indicate that a large number of the transitions have an intraligand character. No relevant direct relativistic effects can be observed on the pattern of the excited states and on energy differences between them as well. The main relativistic effect is due to the metal−sulfur bond contraction, which in contrast has considerable effect on the electronic structures.

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