Eight-membered Rings

Neutral Pentacoordinate and Hexacoordinate Germanium(IV) Complexes: Valence Expansion At Gemanium By Transannular Bonding Of Selenium in an Eight-Membered Ring1

“…Conformation in the Solid-State and Solution Dimethylgermanium Derivative. The commonly accepted nomenclature to describe the conformation of eight-membered rings is used herein; namely the boat−chair ( C S symmetry), boat−boat ( C S symmetry), twist-boat ( C 1 symmetry), and Twist ( C 2 symmetry), which are abbreviated BC, BB, TB, and T, respectively. − Arshinova has noted that the boat conformer ( C 1 symmetry; abbreviated B) should also be considered as it is commonly found in the solid state (Figure ) . The B conformation represents a highly distorted TB geometry about halfway between the symmetric C 2 T and BB geometry .…”

A Neutral Spirocyclic Hexacoordinated Germanium(IV) Complex: Hypervalent Germanium Compounds with Sulfur-Containing Eight-Membered Rings

“…The bonding parameters for both eight-membered rings are identical and both rings are interchanged by a C 2 symmetry operation. The eight-membered rings assume a C s symmetric boat−boat conformation in the solid-state structure of 1 , 6b,− which brings the transannular sulfur and germanium atoms to within bonding distance of each other. See Table for selected bond distances and angles.…”

Synthesis and Conformation of Chiral Eight-Membered 12H-Dibenzo[d,g][1,3,2]dioxaphosphocins1

“…Studies on the conformation of the 12 H -dibenzo[ d,g ][1,3,2]dioxaphosphocin ring have appeared only within the past 10 years. Quite recently, several reviews have appeared on the subject. ,− The commonly accepted nomenclature to describe the conformation of eight-membered rings is used herein; namely the boat−chair ( C s symmetry), boat−boat ( C s symmetry), twist-boat ( C 1 symmetry), and twist ( C 2 symmetry), which are abbreviated BC, BB, TB, and T, respectively. − Arshinova has noted that the boat conformer ( C 1 symmetry; abbreviated B) should also be considered as it is commonly found in the solid state. − The B conformation represents a highly distorted TB geometry about halfway between the symmetric C 2 T and BB geometries . The B conformation is characterized by a C aromatic −O−P−O torsion angle of 0° …”