Two iridanonaborane compounds

Two iridanonaborane compounds, 4-carbonyl-5,6:8,9-bis-μH-4-hydrido-4-bis­(tri­methyl­phosphine)-4-irida-arachno-nonaborane(12), [IrH(B₈H₁₂)(C₃H₉P)₂(CO)], (Ia), and 2-carbonyl-2,5:6,9:8,9-tri-μH-4-chloro-2-bis­(tri­methyl­phosphine)-2-irida-nido-nonaborane(11), [Ir(B₈H₁₀Cl)(C₃H₉P)₂(CO)], (II), are described. Compound (II) shows evidence of effective chlorine-substituent migration during its formation.     

Two orthopalladated chromophores

The title compounds, {5‐(di­methyl­amino)‐2‐[N‐(4‐methoxy­phenyl)­imino­methyl]­phenyl}[N‐(4‐methoxy­phenyl)‐4‐nitro­salicyl­aldiminato]­palladium(II), [Pd(C₁₄H₁₁N₂O₄)(C₁₆H₁₇N₂O)], (I), and [4‐(diethyl­amino)‐N‐(4‐methoxy­phenyl)­sali­cyl­aldiminato]{2‐[N‐(4‐methoxy­phenyl)­imino­methyl]‐5‐nitrophenyl}palladium(II) di­chloro­methane hemisolvate, [Pd(C₁₄H₁₁N₂O₃)(C₁₈H₂₁N₂O₂)]·0.5CH₂Cl₂, (II), both contain push–pull chromophores coordinated to Pd in a square‐planar arrangement. In both compounds, the five‐membered orthopalladated ring is essentially planar, while the coordinated six‐membered ring is not. Deviations from a coplanar arrangement of the phenyl­ene rings of the coordinated Schiff bases are observed in both (I) and (II) as a result of intramolecular steric interactions.     

Two strained hexahelicenophanes

The crystal structures of the [6]­helicenes 4,13‐(1,10‐deca­methyl­ene­dioxy)­hexahelicene, C₃₆H₃₄O₂, (I), and 4,13‐(1,8‐octa­methyl­ene­dioxy)­hexahelicene, C₃₄H₃₀O₂, (II), show strong steric interactions between the terminal benzene rings and the poly­methyl­ene­dioxy chains. The shortest ring A and F distances amount to 2.941 (3) and 2.902 (3) Å, respectively. The increased steric energy of the ground state is responsible for a significantly lower racemization barrier of (I) and (II) in comparison to the unsubstituted [6]­helicene.     

Cocrystallization of Two Different Pseudorotamers of Monocyclic Phosphorane Bearing Two Martin Ligands

Solution and crystal structures of monocyclic pentacoordinate phosphoranes bearing two Martin ligands and two carbon substituents are described. When the two carbon substituents are different, relative apicophilicity of the two monodentate carbon substituents could be determined based on the equilibrium ratio of the pseudorotamers. In some cases, x-ray structural analysis could be carried out and the crystallized structure from CH 3 CN is consistent with the major pseudorotamer in solution (CD 3 CN). Furthermore, when the equilibrium ratio of pseudorotamers is almost unity, novel cocrystallization of two pseudorotamers in a single crystal was observed.     

Two isomeric cucurbitane derivatives

Two isomeric cucurbitane derivatives, 3β,7α,11β‐triacetoxycucurbit‐5(10)‐ene, (I), and 3β,7α,11β‐triacetoxy‐5α‐cucurbit‐1(10)‐ene, (II), both C₃₆H₅₈O₆, have their single endocyclic C=C double bonds in different positions. This results in differences in the conformation of the four‐ring system, which is close to a half‐chair/half‐chair/chair/half‐chair arrangement in (I) and to a half‐chair/twist‐boat/boat/half‐chair arrangement in (II). The orientation of some of the substituents is also different; the 3β‐acetoxy group is in an equatorial position in (I) but in an axial position in (II), while the 11β‐acetoxy group occupies an axial position in (I) and an equatorial position in (II). The asymmetric unit of (I) contains two symmetry‐independent molecules which do not differ significantly, being related by a pseudo‐twofold axis of symmetry. In both structures, the aliphatic chain fragments are disordered and the disorder persists at lower temperatures.