Synthesis and Characterization of a New Structural Type of Diruthenium(III) Complex

The neutral, monocationic, and dicationic linear trinuclear ruthenium compounds [Ru(3)(dpa)(4)(CN)(2)], [Ru(3)(dpa)(4)(CN)(2)][BF(4)], [Ru(3)(dpa)(4)Cl(2)][BF(4)], and [Ru(3)(dpa)(4)Cl(2)][BF(4)](2) (dpa=the anion of dipyridylamine) have been synthesized and characterized by various spectroscopic techniques. Cyclic voltammetric and spectroelectrochemical studies on the neutral and oxidized compounds are reported. These compounds undergo three successive metal-centered one-electron-transfer processes. X-ray structural studies reveal a symmetrical Ru(3) unit for these compounds. While the metal--metal bond lengths change only slightly, the metal--axial ligand lengths exhibit a significant decrease upon oxidation of the neutral complex. The electronic configuration of the Ru(3) unit changes as the axial chloride ligands are replaced by the stronger "pi-acid" cyanide axial ligands. Magnetic measurements and (1)H NMR spectra indicate that [Ru(3)(dpa)(4)Cl(2)] and [Ru(3)(dpa)(4)Cl(2)][BF(4)](2) are in a spin state of S=0 and [Ru(3)(dpa)(4)Cl(2)][BF(4)], [Ru(3)(dpa)(4)(CN)(2)], and [Ru(3)(dpa)(4)(CN)(2)][BF(4)] are in spin states of S=1/2, 1, and 3/2, respectively. These results are consistent with molecular orbital (MO) calculations.

Section: Resultsmentioning

confidence: 94%

Oxidation of Linear Trinuclear Ruthenium Complexes [Ru₃(dpa)₄Cl₂] and [Ru₃(dpa)₄(CN)₂]: Synthesis, Structures, Electrochemical and Magnetic Properties

Kuo

Liu

Yeh

et al. 2007

“…Ru 2 III -bis-alkynyl complexes, [20,37] and is attributed to a second-order Jahn-Teller effect. [38] Molecular structures of asymmetric compounds 4, 5, and 7 ( Figure 2) closely resemble those of the symmetric compounds, especially in terms of geometric parameters associated with the RuÀRu, RuÀCa, and RuÀN bonds.…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Bis‐alkynyl Diruthenium Compounds with Built‐in Electronic Asymmetry: Toward an Organometallic Aviram–Ratner Diode

Ying

Cordova

Ren

et al. 2007

Conditions to prepare trans-[Ru2(dmba)4(C[triple chemical bond]CAr)2] from [Ru2(dmba)4(NO(3))2] (DMBA=N,N'-dimethylbenzamidinate) and HC[triple chemical bond]CAr were optimized; Et2NH was found to be the most effective among a number of weak bases in facilitating the product formation. Furthermore, a series of unsymmetric trans-[(ArC[triple chemical bond]C)Ru(2)(dmba)4(C[triple chemical bond]CAr')] compounds were prepared under optimized conditions, in which one or both of Ar and Ar' are donor (NMe2)-/acceptor (NO(2))-substituted phenyls. While the X-ray crystallographic studies revealed a minimal structural effect upon donor/acceptor substitution, voltammetric measurements indicated a significant influence of substituents on the energy level of frontier orbitals. In particular, placing a donor and an acceptor on the opposite ends of trans-[(ArC[triple chemical bond]C)Ru2(dmba)4(C[triple chemical bond]CAr')] moiety results in an energetic alignment of frontier orbitals that favors a directional electron flow, a necessary condition for unimolecular rectification.

“…Of particular interest is the short distance between the two metal atoms in these complexes. [18] Thus, in [Nb 2 A C H T U N G T R E N N U N G (hpp) 4 ], [18a] the Nb À Nb bond length is 220.35(9) pm, and in [Ru 2 Cl 2 A C H T U N G T R E N N U N G (hpp) 4 ], [19] which exhibits two unpaired electrons, a RuÀRu distance of 232.1 pm was measured.…”

mentioning

confidence: 99%

A New Class of Binuclear Gallium Hydrides: Synthesis and Properties of [{GaCl(hpp)H}₂] (hpp=1,3,4,6,7,8‐Hexahydro‐2H‐pyrimido[1,2‐a]pyrimidate)

Robinson

Tang

Köppe

et al. 2007

Herein we report on the synthesis and characterization of the first representative of a new class of gallium hydrides, namely [{GaCl(hpp)H}2] (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidate). Our X-ray diffraction data suggest the presence of weak H--H contacts between adjacent [{GaCl(hpp)H}2] molecules in the crystal. With the aid of quantum-chemical calculations, the pathway of its formation starting with the adduct H2ClGaNMe3 and the pyrimidine hppH were analyzed. [{GaCl(hpp)H}2] slowly decomposes at 25 degrees C, a process which presumably leads under H2 elimination to [{GaCl(hpp)}2]. Although we were not yet able to characterize [{GaCl(hpp)}2] experimentally, DFT calculations provide information about its likely structure. According to these calculations, the molecule features a Ga--Ga single bond.