Bisaryl and Bisalkynyl Diruthenium (III,III) Compounds Based on an Electron-Deficient Building Block.

Reported herein is a new series of diruthenium(III,III) bisalkynyl and bisaryl diruthenium(III,III) compounds supported with 2-amino-3-(trifluoromethyl)pyridinate (amtfmp). Using Ru 2 (amtfmp) 4 Cl 2 from a modified preparation, cis 2:2 Ru 2 (amtfmp) 4 (C≡CPh) 2 ( 1 ), cis 2:2 Ru 2 (amtfmp) 4 (Ph) 2 ( 2 ), and 3:1 Ru 2 (amtfmp) 4 (Ph) 2 ( 3 ) were synthesized via a lithium-halogen exchange reaction using LiC 2 Ph and LiPh, respectively. Compounds 1 - 3 are all Ru 2 (III,III) species with a ground-state configuration of π 4 δ 2 (π*) 4 ( S = 0) and were characterized via mass spectrometry, electron absorption and 1 H/ 19 F NMR spectroscopies, and voltammetry. The molecular structures of 1 - 3 were established using single-crystal X-ray diffraction analysis, and preliminary density functional theory analysis was performed to elaborate the electronic structures of 1 and 2 . Comparisons of the electrochemical properties of 1 - 3 against the Ru 2 (amtfmp) 4 Cl 2 starting material reveal cathodic shifts of the Ru 2 7+/6+ oxidation and the Ru 2 6+/5+ and Ru 2 5+/4+ reduction potentials. In comparison to related Ru 2 (III,III) bisalkynyl and bisaryl compounds, the electrode potentials for 1 - 3 are anodically shifted up to ca. 0.95 V, highlighting the strong electron-withdrawing nature of the amtfmp ligand.