X-ray crystal structures of: [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]•2NCC6H4 AND Ba1.5[Fe(C10H13N2O7)][Co(CN)6]•9H2O; two crystallographic challenges

The novel compound, [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4] was synthesized. Crystal structures of [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]·2NCC6H5 and Ba1.5[Fe(C10H13N2O7)][Co(CN)6]·9H2O were determined employing a Rigaku Mercury375R/M CCD (XtaLAB mini) diffractometer with graphite monochromated Mo-Kα radiation. For [Rh2(N-{2,4,6-CH3}C6H2)COCH3)4]·2NCC6H5, the space group was P-421c(#114) with unit cell dimensions: a =11.0169(14)Å, c =21.499(3)Å, V = 2609.4(6)Å3. Each rhodium had approximately octahedral coordination and was bound to another rhodium atom, two nitrogens (trans to each other), two oxygens (trans to each other), and one benzonitrile nitrogen (trans to rhodium). For Ba1.5[Fe(C10H13N2O7)][Co(CN)6]·9H2O the space group was: P-1(#2) with unit cell dimensions: a=13.634Å, b=13.768Å, c=17.254Å and α=84.795°, β=87.863°, γ=78.908°, V=3164.5Å3. The iron atom (nearly octahedral) was coordinated to one chelating ligand (derived from ethylenediaminetetraacetic acid) and the nitrogen of a cyanide ligand. The carbon of the cyanide ligand was bound to cobalt (octahedral). Thus, the cyanide ligand serves as a bridge between the two metals

Bimetallic Cooperativity in Proton Reduction with an Amido‐Bridged Cobalt Catalyst

The bimetallic catalyst [CoII2(L1)(bpy)2]ClO4 (1), in which L1 is an [NN′2O2] fused ligand, efficiently reduced H+ to H2 in CH3CN in the presence of 100 equiv of HOAc with a turnover number of 18 and a Faradaic efficiency of 94 % after 3 h of bulk electrolysis at −1.6 V (vs. Ag/AgCl). This observation allowed the proposal that this bimetallic cooperativity is associated with distance, angle, and orbital alignment of the two Co centers, as promoted by the unique Co−Namido−Co environment offered by L1. Experimental results revealed that the parent [CoIICoII] complex undergoes two successive metal‐based 1 e− reductions to generate the catalytically active species [CoICoI], and DFT calculations suggested that addition of a proton to one CoI triggers a cooperative 1 e− transfer by each of these CoI centers. This 2 e− transfer is an alternative route to generate a more reactive [CoII(CoII−H−)] hydride, thus avoiding the CoIII−H− required in monometallic species. This [CoII(CoII−H−)] species then accepts another H+ to release H2

Tetrakis[μ-N-(2,4,6-Trimethylphenyl)Acetamidato]-κ\u3csup\u3e4\u3c/sup\u3eN: O;κ\u3csup\u3e4\u3c/sup\u3e O:N-bis[(Benzonitrile-κN)Rhodium(II)](Rh - Rh)

The title structure, [Rh2(C11H14NO) 4(C7H5N)2], contains a dinuclear Rh complex of point symmetry 4̄ with an Rh - Rh unit and two benzonitrile ligands located in special positions along the twofold axis passing through 4̄. Four symmetry-equivalent mesitylacetamidate ligands bridge the Rh - Rh unit. Thus, each RhII atom has an approximately octahedral coordination by one Rh [Rh - Rh = 2.4290 (6) Å], two acetamidate O atoms trans to each other [Rh - O = 2.044 (3) Å], two acetamidate N atoms trans to each other [Rh - N = 2.091 (4) Å], and a benzonitrile N atom trans to Rh [Rh - N = 2.222 (3) Å]. The structure is held together by weak van der Waals forces

(3-Methylbenzonitrile-κN)tetrakis(μ-N-phenylacetamidato) -κ\u3csup\u3e4\u3c/sup\u3eN:O;κ\u3csup\u3e4\u3c/sup\u3eO:N-dirhodium(II)(Rh-Rh)

In the title compound, [Rh2(C8H8NO) 4(C8H7N)], the four acetamidate ligands bridging the dirhodium core are arranged in a 2,2-trans manner. One Rh IIatom is five-coordinate, in a distorted pyramidal geometry, while the other is six-coordinate, with a disorted octahedral geometry. For the six-coordinate RhIIatom, the axial nitrile ligand shows a non-linear Rh-nitrile coordination with an Rh-N-C bond angle of 166.4 (4)° and a nitrile N-C bond length of 1.138 (6) Å. Each unique RhIIatom is coordinated by a trans pair of N atoms and a trans pair of O atoms from the four acetamide ligands. The Neq-Rh-Rh-Oeq torsion angles on the acetamide bridge varies between 12.55 (11) and 14.04 (8)°. In the crystal, the 3-methylbenzonitrile ring shows a π-π interaction with an inversion-related equivalent [interplanar spacing = 3.360 (6) Å]. A phenyl ring on one of the acetamide ligands also has a face-to-face π-π interaction with an inversion-related equivalent [interplanar spacing = 3.416 (5) Å]

Cis-Tetrakis(μ-N-Phenylacetamidato)-κ\u3csup\u3e4\u3c/sup\u3e N:O;κ\u3csup\u3e4\u3c/sup\u3e O:N-bis[(Benzonitrile-κN)Rhodium(II)](Rh - Rh)

The complex molecule of the title compound, [Rh2{N(C 6H5)COCH3}4(C6H5CN)2], exhibits crystallographically imposed centrosymmetry. The four acetamide ligands bridging the dirhodium core are arranged in a 2,2-cis manner, with two N atoms and two O atoms coordinating to the unique RhII atom cis to one another. The Neq - Rh - Rh - Oeq torsion angles on the acetamide bridges vary between 1.62 (4) and 1.78 (4)°. The Rh - Rh bond length is 2.4319 (3) Å. The axial nitrile ligand completes the distorted octahedral coordination sphere and shows a non-linear coordination with an Rh - N - C bond angle of 167.14 (15)°, while the N - C bond length is 1.135 (3) Å

Crystal structure of tetrakis(μ-N-phenylacetamidato)-κ4N:O;κ4O:N-bis[(2-methylbenzonitrile-κN)rhodium(II)](Rh—Rh)

The complex molecule of the title compound, [Rh2{N(C6H5)COCH3}4(C8H7N)2], exhibits inversion symmetry. The four acetamidate ligands bridging the dirhodium core are arranged in a 2,2-trans manner with two N atoms and two O atoms coordinating to each RhII atom trans to one another. The Neq—Rh—Rh—Oeq torsion angles on the acetamidate bridge vary between −4.07 (5) and −6.78 (7)°. The axial nitrile ligands complete the distorted octahedral coordination sphere of each RhII atom and show a nonlinear coordination with Rh—N—C bond angles of 151.6 (3) and 152.5 (3)°. The bond lengths of the two nitrile triple bonds are 1.133 (5) and 1.137 (5) Å