Supramolecular Isomerism of 2,2′‐Bipyrazine Complexes with cis ‐(NH 3 ) 2 Pt II : Ligand Rotational State and Sequential Orientation Determine the 3D Shape of Metallacycles

Insight into systematic formation of hexafluorosilicate during crystallization via self-assembly in a glass vessel

Formation of the unexpected hexafluorosilicate (SiF₆²⁻) anion during crystallization via self-assembly in glassware is scrutinized. Self-assembly of M(BF₄)₂ (M²⁺ = Cu²⁺ and Zn²⁺) with tridentate N-donors (L) in a mixture solvent including methanol in a glass vessel gives rise to an SiF₆²⁻-encapsulated Cu₃L₄ double-decker cage and a Zn₂L₄ cage, respectively. Induced reaction of CuX₂ (X⁻ = PF₆⁻ and SbF₆⁻) instead of Cu(BF₄)₂, with the tridentate ligands, produces the same species. The formation time of SiF₆²⁻ is in the order of anions BF₄⁻ < PF₆⁻ < SbF₆⁻ under the given reaction conditions. The SiF₆²⁻ anion, acting as a cage template or cage-to-cage bridge, seems to be formed from the reaction of polyatomic anions containing fluoride with the SiO₂ of the surface of the glass vessel.

Formation of the unexpected hexafluorosilicate (SiF₆²⁻) encapsulated cages constructed. Interestingly, this shows that the surface of glassware should be given serious consideration for long-duration reactions with active F-containing species.

Assembled structures of tetrakis(biimidazole)dirhodium complexes hydrogen-bonded with common inorganic anions

Eight new structures of dirhodium complexes, each with four biimidazole (H2bim) ligands, were obtained: [Rh2(H2bim)4(H2O)2](NO3)4·4H2O (I), [Rh2(H2bim)4(H2O)2](ClO4)4·5H2O (II), [Rh2(H2bim)4(MeOH)2](ClO4)4 (III), [Rh2(H2bim)4(DMF)2](BF4)4 (IV), [Rh2(H2bim)4(Mepy)2](SiF6)2·8H2O (V), [{Rh2(H2bim)4(pz)}2(μ-pz)](SiF6)(ClO4)6·12.7H2O (VI), [{Rh2(H2bim)4(pz)}2(μ-pz)](ClO4)8·11.4H2O (VII) and [Rh2(H2bim)4(μ-pz)](SiF6)2·6H2O (VIII). The unbridged Rh-Rh bond distances range between 2.6313 (8) and 2.7052 (5) Å. The dirhodium units adopt a staggered conformation with torsion angles N-Rh-Rh-N of 37.6 (4)-48.98 (8)°. Various assembled structures were constructed by hydrogen bonding between the complexes and the anions: a discrete structure in (IV), one-dimensional structure in (II), two-dimensional structures in (I), (III), (VI), (VII) and (VIII) and a three-dimensional structure in (V).