Bisaryl Diruthenium(III) Paddlewheel Complexes: Synthesis and Characterization

Abstract

Aryls represent a class of both σ- and π-donating electron-rich axial ligands that is underexplored in the field of metal–metal multiply bonded paddlewheel species. By a decrease in the steric bulk around the diruthenium axial sites and an increase in the basicity of the bridging ligands, the first examples of bisaryl diruthenium­(III) paddlewheel complexes have been isolated. Compounds of the form Ru2(DMBA)4Ar2 (DMBA = N,N′-dimethylbenzamidinate, Ar = C6H4-4- t Bu (1), C6H5 (2), C6H3-3,5-(OCH3)2 (3)) were synthesized via a lithium–halogen exchange reaction between Ru2(DMBA)4Cl2 and excess LiAr and characterized using mass spectrometry, electronic absorption spectroscopy, cyclic and differential pulse voltammetry, and 1H NMR spectroscopy. The molecular structures of compounds 1–3 were established using single-crystal X-ray diffraction analysis and their electronic structures (both ground and excited state) analyzed using density functional theory calculations.

Control of dominant conduction orbitals by peripheral substituents in paddle-wheel diruthenium alkynyl molecular junctions

“…6 . 32 As a result, the Ru 2 complexes gain some σ bonding nature between the two Ru atoms, which may enhance the hole transport process through the HOMO orbital.…”

“…One notable feature of HOMO and HOMO-1 is the overlap between the dπ* orbitals of the Ru cores due to the SOJT distortion as shown in Figure 6. 32 As a result, the Ru2 complexes gain some σ bonding nature between the two Ru atoms, which may enhance the hole transport process through the HOMO orbital.…”

Synthetic Strategies for Trapping the Elusive trans-Dirhodium(II,II) Formamidinate Isomer: Effects of Cis versus Trans Geometry on the Photophysical Properties

“…In order to elucidate the mechanism of DTolF migration, optimization calculations with Grimme’s dispersion corrections and a PCM with acetonitrile were undertaken for 2 and 3 and for two possible intermediates (Figures S8 and S9). − The calculated species, cis / trans -[Rh 2 (μ-DTolF)­(κ-DTolF)­(qxnp)­(MeCN) 3 ] 2+ and cis / trans -[Rh 2 (μ-DTolF)­(κ-DTolF)­(np)­(MeCN) 3 ] 2+ , are proposed as intermediates in a pathway for migration of the formamidinate bridging ligand. The logical first step of the migration is Rh 1 –N 1 bond scission, rotation along the remaining Rh 2 –N 2 bond, and binding of N 1 to Rh 2 in the axial position by displacement of the axial MeCN molecule.…”

pH- and Time-Dependent Release of Phytohormones from Diruthenium Complexes

“…SCF-Xα-SW calculations carried out on [Ru 2 (μ-O 2 CR) 4 ] + complexes showed that the Ru 2 5+ unit shows a quasi-degeneration of the π* and δ* energy levels, leading to a Qπ *2 δ* electronic configuration (where Q denotes the underlying σ 2 π 4 δ 2 core) with three unpaired electrons and a metal–metal bond order of 2.5 . The use of amidinate ligands, which have a higher donor character in comparison to carboxylates, allows isolation of not only Ru 2 4+ and Ru 2 5+ compounds but also Ru 2 6+ compounds. , Again, the Ru 2 5+ oxidation state is the most common one in this family of compounds. Furthermore, heteroleptic compounds with different ratios of carboxylate/amidinate bridging ligands can be prepared by varying the synthetic conditions employed .…”