New complexes of chromium(III) containing organic π-radical ligands: an experimental and density functional theory study.

The electronic structures of a series of chromium complexes 1-7 have been experimentally investigated using a combination of X-ray crystallography, magneto- and electrochemistry, and Cr K-edge X-ray absorption and UV-vis spectroscopies. Reaction of the dimer [Cr(II)2(μ-CH3CO2)4](0) with 2,2'-bipyridine (bpy(0)) produced the complex [Cr(III)(bpy(0))(bpy(•))(CH3CO2)2](0) (S = 1) (1), but in the presence of isopropylamine ((i)PrNH2) [Cr(III)(bpy(•))((i)PrNH2)2(CH3CO2)2](0) (S = 1) (2) was obtained. Both 1 and 2 contain a Cr(III) ion and a single (bpy(•))(1-) ligand, so are not low-spin Cr(II) species.

Wiring terpyridine: approaches to alkynylthienyl 2,2':6',2''-terpyridines.

The reaction of triisopropylsilylethyne or trimethylsilylethyne with 4'-(5-bromo-2-thienyl)-2,2':6',2''-terpyridine () leads to 4'-(5-triisopropylsilylethynyl-2-thienyl)-2,2':6',2''-terpyridine () or 4'-(5-trimethylsilylethynyl-2-thienyl)-2,2':6',2''-terpyridine (). The latter compound may be deprotected to give 4'-(5-ethynyl-2-thienyl)-2,2':6',2''-terpyridine (). Treatment of the complexes [Ru()(2)][PF(6)](2), [Ru(tpy)()][PF(6)](2) and [Ru()(2)][PF(6)](2) ( = 4'-(4-bromo-2-thienyl)-2,2':6',2''-terpyridine) with triisopropylsilylethyne yields the corresponding homoleptic and heteroleptic alkynylthienyl-terminated ruthenium(ii) complexes, for which spectroscopic and electrochemical data are presented.

Redox-switched oxidation of dihydrogen using a non-innocent ligand.

Organometallic complexes containing non-innocent ligands of the type Cp*Ir(tBAFPh)(1), where H2tBAFPh is 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, were found to activate H2 in a redox-switchable manner. The 16e- complex 1 was inert with respect to H2, CO, as well as conventional basic substrates until oxidation. Oxidation of 16-electron 1 with 1 equiv of Ag+ resulted in ligand-centered oxidation affording salts of [1]+, which were characterized by crystallographically, EPR, and elemental analyses.

Molecular and electronic structure of square planar complexes [PdII(tbpy)(L N,O IP)]0, [PdII(tbpy)(LN,O ISQ)](PF6), and [PdII(tbpy)(L N,O IBQ)](PF6)(BF4).2CH2Cl2: an o-iminophenolato based ligand centered, three-membered redox series.

Three Pd(II) complexes which are members of the same electron-transfer series have been synthesized. Refluxing of the reaction mixture containing equimolar amounts of PdCl(2), 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol (H(2)L(N,O)), 4,4'-di-tert-butyl-2,2'-dipyridyl ((t)bpy), and 3 equiv of triethylamine in MeOH under an argon atmosphere followed by exposure to air and addition of KPF(6) after cooling to room temperature yields reddish brown crystals of paramagnetic (S = 1/2) [Pd(L(N,O)(ISQ))((t)bpy)](PF6) (2). Reaction of 2 with one equiv of [CoCp2] in dry and degassed CH(2)Cl(2) using anaerobic conditions gives diamagnetic [Pd(L(N,O)(IP))((t)bpy)] (1), which is the one-electron reduced form of 2.