Groups 5 and 6 terminal hydrazido(2-) complexes: N β substituent effects on ligand-to-metal charge-transfer energies and oxidation states

Ian A. Tonks, Alec C. Durrell, Harry B. Gray, John E. Bercaw

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Brightly colored terminal hydrazido(2-) (dme)MCl 3(NNR 2) (dme = 1,2-dimethoxyethane; M = Nb, Ta; R = alkyl, aryl) or (MeCN)WCl 4(NNR 2) complexes have been synthesized and characterized. Perturbing the electronic environment of the β (NR 2) nitrogen affects the energy of the lowest-energy charge-transfer (CT) transition in these complexes. For group 5 complexes, increasing the energy of the N β lone pair decreases the ligand-to-metal CT (LMCT) energy, except for electron-rich niobium dialkylhydrazides, which pyramidalize N β in order to reduce the overlap between the Nb=N α π bond and the N β lone pair. For W complexes, increasing the energy of N β eventually leads to reduction from formally [W VI≡N-NR 2] with a hydrazido(2-) ligand to [W IV=N=NR 2] with a neutral 1,1-diazene ligand. The photophysical properties of these complexes highlight the potential redox noninnocence of hydrazido ligands, which could lead to ligand- and/or metal-based redox chemistry in early transition metal derivatives.

Original languageEnglish (US)
Pages (from-to)7301-7304
Number of pages4
JournalJournal of the American Chemical Society
Volume134
Issue number17
DOIs
StatePublished - May 2 2012

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