Structural and Oxidation State Alternatives in Platinum and Palladium Complexes of a Redox-Active Amidinato Ligand

Reaction of [Pt(DMSO)₂ Cl₂ ] or [Pd(MeCN)₂ Cl₂ ] with the electron-rich LH=N,N'-bis(4-dimethylaminophenyl)ethanimidamide yielded mononuclear [PtL₂ ] (1) but dinuclear [Pd₂ L₄ ] (2), a paddle-wheel complex. The neutral compounds were characterized through experiments (crystal structures, electrochemistry, UV-vis-NIR spectroscopy, magnetic resonance) and TD-DFT calculations as metal(II) species with noninnocent ligands L^- . The reversibly accessible cations [PtL₂ ]⁺ and [Pd₂ L₄ ]⁺ were also studied, the latter as [Pd₂ L₄ ][B{3,5-(CF₃ )₂ C₆ H₃ }₄ ] single crystals. Experimental and computational investigations were directed at the elucidation of the electronic structures, establishing the correct oxidation states within the alternatives [Pt^II (L^- )₂ ] or [Pt^. (L )₂ ], [Pt^II (L^0.5- )₂ ]⁺ or [Pt^III (L^- )₂ ]⁺ , [(Pd^II )₂ (μ-L^- )₄ ] or [(Pd^1.5 )₂ (μ-L^0.75- )₄ ], and [(Pd^2.5 )₂ (μ-L^- )₄ ]⁺ or [(Pd^II )₂ (μ-L^0.75- )₄ ]⁺ . In each case, the first alternative was shown to be most appropriate. Remarkable results include the preference of platinum for mononuclear planar [PtL₂ ] with an N-Pt-N bite angle of 62.8(2)° in contrast to [Pd₂ L₄ ], and the dimetal (Pd₂ ⁴⁺ →Pd₂ ⁵⁺ ) instead of ligand (L^- →L ) oxidation of the dinuclear palladium compound.

Metal carbonyl complexes of potentially ambidentate 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole acceptors

The compounds [W(CO)5(btd)], [W(CO)5(bsd] and [Re(CO)3(bpy)(bsd)](BF4), btd=2,1,3-benzothiadiazole and bsd=2,1,3-benzoselenadiazole were isolated and characterized experimentally (crystal structure, spectroscopy, spectroelectrochemistry) and by density functional theory calculations. The results confirm single N-coordination in all cases, binding to Se was calculated to be less favorable. Studies of one-electron reduced forms indicate that the N-coordination is maintained during electron transfer.

Metal-Chelating N,N'-Bis(4-dimethylaminophenyl)acetamidinyl Radical: A New Chromophore for the Near-Infrared Region

A new non-innocent ligand redox system, N,N'-bis(4-dimethylaminophenyl) substituted acetamidinato/acetamidinyl, has been designed and described by example of structurally and spectroscopically characterized ruthenium complexes. The hitherto unreported ligand is responsible for rather intense and narrow absorptions in the near-infrared region of the one- and two-electron oxidized forms. The spectroscopic, computational, and first structural characterization of an amidinyl radical complex adds to the list of established N-based radical ligands.

Tetra-μ3-iodido-tetra-kis-[(tri-n-butyl-phosphane-κP)copper(I)]

The title complex, [Cu₄I₄(C₁₂H₂₇P)₄], crystallizes with six mol­ecules in the unit cell and with three independent one-third mol­ecule fragments, completed by application of the relevant symmetry operators, in the asymmetric unit. The tetranuclear copper core shows a tetrahedral geometry (site symmetry 3..). The I atoms also form a tetra­hedron, with I⋯I distances of 4.471 (1) Å. Both tetra­hedra show an orientation similar to that of a pair of self-dual platonic bodies. The edges of the I-tetra­hedral structure are capped to the face centers of the Cu-tetra­hedron and vice versa. The Cu_face⋯I distances are 2.18 Å (averaged) and the I_face⋯Cu distances are 0.78 Å (averaged). As a geometric consequence of these properties there are eight distorted trigonal–bipyramidal polyhedra evident, wherein each trigonal face builds up the equatorial site and the opposite Cu⋯I positions form the axial site. As expected, the n-butyl moieties are highly flexible, resulting in large elongations of their anisotropic displacement parameters. Some C atoms of the n-butyl groups were needed to fix alternative discrete disordered positions.

Discovering more non-innocence: triazenido versus triazenyl radical ligand function, and a comment on [NO2]n as a "suspect" ligand

The unusual suspects: Depending on co-ligands L(n) and the effects of substituents (R), the well-known triazenides [N(NR)2](-) may act as EPR detectable coordinated triazenyl ligands, [N(NR)2](·). They are thus new non-innocent ligands and are related to the hitherto unused non-innocent nitrogen dioxide ligand, [NO2](·).