Facile Synthesis and Redox Behavior of an Overcrowded Spirogermabifluorene

A spirogermabifluorene that bears sterically demanding 3,3′,5,5′-tetra(t-butyl)-2,2′-biphenylene groups (1) was obtained from the reaction of in-situ-generated 2,2′-dilithiobiphenylene with GeCl2·(dioxane). The solid-state structure and the redox behavior of 1 were examined by single-crystal X-ray diffraction analysis and electrochemical measurements, respectively. The sterically hindered biphenyl ligands endow 1 with high redox stability and increased electron affinity. The experimental observations were corroborated by theoretical DFT calculations.

A tris-spiro metalla-aromatic system featuring Craig-Möbius aromaticity

As aromaticity is one of the most fundamental concepts in chemistry, the construction of aromatic systems has long been an important subject. Herein, we report the synthesis and characterization of a tris-spiroaromatic complex, hexalithio spiro vanadacycle 2. The delocalization of the four electrons within the two V 3d orbitals and the π* orbitals of the three biphenyl ligands leads to a 40π Craig-Möbius aromatic system with three metalla-aromatic rings, as revealed by both experimental measurements and theoretical analyses. For comparison, if Cr is used instead of V, a similar Craig-Möbius aromatic system can not be generated. In this case, pentalithio spiro chromacycle 3 is obtained, and the Cr center uses its two 3d orbitals to form two independent metalla-aromatic rings. This work presents a type of aromatic systems that will contribute to both aromaticity theory and organometallic chemistry.

A two-dimensional Zn coordination polymer with a three-dimensional supramolecular architecture

The title compound, poly[bis{μ2-4,4′-bis[(1,2,4-triazol-1-yl)methyl]biphenyl-κ2N4:N4′}bis(nitrato-κO)zinc(II)], [Zn(NO3)2(C18H16N6)2]n, is a two-dimensional zinc coordination polymer constructed from 4,4′-bis[(1H-1,2,4-triazol-1-yl)methyl]-1,1′-biphenyl units. It was synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The ZnIIcation is located on an inversion centre and is coordinated by two O atoms from two symmetry-related nitrate groups and four N atoms from four symmetry-related 4,4′-bis[(1H-1,2,4-triazol-1-yl)methyl]-1,1′-biphenyl ligands, forming a distorted octahedral {ZnN4O2} coordination geometry. The linear 4,4′-bis[(1H-1,2,4-triazol-1-yl)methyl]-1,1′-biphenyl ligand links two ZnIIcations, generating two-dimensional layers parallel to the crystallographic (132) plane. The parallel layers are connected by C—H...O, C—H...N, C—H...π and π–π stacking interactions, resulting in a three-dimensional supramolecular architecture.

catena-Poly[[(dichloridozinc)-μ-4,4′-bis(1H-imidazol-1-yl)biphenyl-κ2N3:N3′] 0.25-hydrate]

In the title one-dimensional coordination polymer, {[ZnCl2(C18H14N4)]·0.25H2O}n, the ZnIIatom is coordinated by two chloride ions and two 4,4′-bis(1H-imidazol-1-yl)biphenyl ligands, generating a distorted tetrahedral ZnCl2N2geometry. The dihedral angle between the benzene rings of the ligand is 51.0 (1)° and the dihedral angles between the benzene rings and their attached imidazole rings are 18.7 (2) and 45.9 (1)°. The bridging ligand leads to [10-1] polymeric chains in the crystal and the disordered water molecule (occupancy 0.25) forms O—H...Cl hydrogen bonds.