[(1,2,5,6-η)-Cycloocta-1,5-diene](1-ethyl-3-isopropyl-1,3-imidazol-2-ylidene)(triphenylphosphane)rhodium(I) tetrafluoridoborate

A new N-heterocyclic cationic rhodium(I) complex with a tetrafluoridoborate counter-anion, [Rh(C8H14N2)(C8H12)(C18H15P)]BF4, has been prepared and structurally characterized. The cationic complex exhibits a distorted square-planar environment around the rhodium(I) ion. Two connections are made from rhodium(I) to the carbon atom of an N-heterocylic carbene ligand and to the phosphorus atom of a triphenylphosphane ligand. The remaining two coordination sites are made via a bidentate interaction from the two olefinic bonds of cyclooctadiene to the rhodium(I) ion. The compound includes an out-sphere tetrafluoridoborate counter-anion. Within the crystal of the compound exist several weak intermolecular C—H...F interactions.

Hexanuclear copper(II) complex of 2-hydroxy-N,N′-bis[1-(2-hydroxyphenyl)ethylidene]propane-1,3-diamine incorporating an open-cubane core

The title molecular structure, namely, diaquatris(μ3-1,3-bis{[1-(2-oxidophenyl)ethylidene]amino}propan-2-olato)-μ3-hydroxido-dinitratohexacopper(II) ethanol trisolvate, [Cu6(C19H19N2O3)3(NO3)2(OH)(H2O)2]·3C2H5OH, corresponds to a non-symmetric hexanuclear copper complex. The complex exhibits one core in which three CuII metal centres are mutually interconnected, two by two, via three phenolato oxygen anions acting in a μ2-mode. These three copper cations are interconnected in a μ3-mode by one hydroxyl group. An open-cube structure is generated in which each of the CuII cations of the three CuO4N units is connected by two μ2-O anions from phenolate groups and one μ3-O atom from a hydroxy anion. Each of the three pentacoordinated CuII cations situated in the open-cube unit has a distorted NO4 square-pyramidal environment. Each of these three CuII centres is interconnected with another CuII cation via one enolate O atom in μ2-mode, yielding one CuNO4 unit and two CuNO3 units. The pentacoordinated CuII atom has a distorted square-pyramidal environment while the two tetracoordinated copper(II) cations are situated in a square-planar environment. A series of intramolecular O—H...O hydrogen bonds are observed. In the crystal, the units are connected two by two by intermolecular C—H...O and O—H...O hydrogen bonds, thus forming sheets parallel to the ac plane.

Crystal structure of (N^C) cyclometalated AuIII diazide at 100 K

The title compound, an (N^C)-cyclometalated gold(III) diazide, namely, diazido[5-ethoxycarbonyl-2-(5-ethoxycarbonylpyridin-2-yl)phenyl-κ2 C 1,N]gold(III), [Au(C17H16NO4)(N3)2] or Au(ppyEt)(N3)2, was synthesized by reacting Au(ppyEt)Cl2 with NaN3 in water for 24 h. The complex has been structurally characterized and features a gold center with a square-planar environment. The Au—N(azide) bond lengths are significantly different depending on the influence of the atom trans to the azide group [Au—N(trans to C) of 2.067 (2) Å versus Au—N(trans to N) of 2.042 (2) Å]. The azide groups are twisted in-and-out of plane by 56.2 (2)°.

Robust navigation of a soft growing robot by exploiting contact with the environment

Navigation and motion control of a robot to a destination are tasks that have historically been performed with the assumption that contact with the environment is harmful. This makes sense for rigid-bodied robots, where obstacle collisions are fundamentally dangerous. However, because many soft robots have bodies that are low-inertia and compliant, obstacle contact is inherently safe. As a result, constraining paths of the robot to not interact with the environment is not necessary and may be limiting. In this article, we mathematically formalize interactions of a soft growing robot with a planar environment in an empirical kinematic model. Using this interaction model, we develop a method to plan paths for the robot to a destination. Rather than avoiding contact with the environment, the planner exploits obstacle contact when beneficial for navigation. We find that a planner that takes into account and capitalizes on environmental contact produces paths that are more robust to uncertainty than a planner that avoids all obstacle contact.

Crystal structure of a polymorph of μ-oxido-bis[(5,10,15,20-tetraphenylporphyrinato)iron(III)]

The title compound, [Fe2(C44H28N4O)2O], was obtained as a by-product during the synthesis of FeIII tetraphenylporphyrin perchlorate. It crystallizes as a new polymorphic modification in addition to the orthorhombic form previously reported [Hoffman et al. (1972). J. Am. Chem. Soc. 94, 3620–3626; Swepston & Ibers (1985) Acta Cryst. C41, 671–673; Kooijmann et al. (2007). Private Communication (refcode 667666). CCDC, Cambridge, England]. In its crystal structure, the two crystallographically independent FeIII cations are coordinated in a square-planar environment by the four N atoms of a tetraphenylporphyrin ligand. The FeIII-tetraphenylporphyrine units are linked by a μ2-oxido ligand into a dimer with an Fe—O—Fe angle close to linearity. The final coordination sphere for each FeIII atom is square-pyramidal with the μ2-oxido ligand in the apical position. The crystal under investigation consisted of two domains in a ratio of 0.691 (3): 0.309 (3).

Crystal structure of the [(1,3-dimesityl-1H-imidazol-3-ium-2-yl)methanolato]copper(II) chloride dimer: insertion of formaldehyde into a copper–carbene bond

The crystal structure of bis[μ-(1,3-dimesityl-1H-imidazol-3-ium-2-yl)methanolato-κ2 O:O]bis[dichloridocopper(II)], [Cu2Cl4(C22H26N2O)2], is reported. The complex is assumed to have formed via the insertion of formaldehyde into the copper–carbon bond in an N-heterocyclic carbene complex of copper(I) chloride. The structure of the binuclear molecule possesses a crystallographically centrosymmetric Cu2O2 central core with the O atoms bridging between the CuII atoms and thus Z′ = 0.5. The copper centres are further ligated by two chloride ligands, resulting in the CuII atoms residing in a distorted square-planar environment. The Cu—O bond lengths are shorter than those previously reported in structures with the same central Cu2O2 motif. The complex displays C—H...Cl interactions involving the H atoms of the heterocycle backbone and the chloride ligands of a neighbouring molecule.

(2-{[2-(Dimethylamino)ethyl]iminomethyl}benzenethiolato-κ3 N,N′,S)(4-methoxybenzenethiolato-κS)nickel(II)

In the title compound, [Ni(C11H15N2S)(C7H7OS)] or [Ni(NNImS)(4-OCH3PhS)] (NNImS = 2-{[2-(dimethylamino)ethyl]iminomethyl}benzenethiolato), the NiII cation is coordinated by a tridentate NNImS ligand and a monodentate thiolate ligand giving an N2S2 coordination set defining an almost square-planar environment. The Ni—Namine bond in the coordination plane is approximately 0.1 Å longer than the Ni—Nimine bond.