Coordination Chemistry at Carbon: The Patchwork Family Comprising (Ph3P)2C, (Ph3P)C(C2H4), and (C2H4)2C

摘要

For about two centuries, coordination chemistry was a domain of main-group and transition-metal chemistry with metal atoms (as in tetracarbonyl nickel(O)) or ions (as in tetrafluoroberyllate(II) or dicyanoaurate(I)) serving as coordination centers for a large variety of neutral or anionic ligands. Typically, the metal centers were considered as positively charged or otherwise electron-deficient acceptors keen to accommodate any electron-rich donors with the resulting types of bonding ranging from purely electrostatic (ion-ion or ion-dipole) to covalent electron-sharing. Concepts such as the rare-gas rules or simply excessive charge accumulation and steric crowding were established to explain the structures and the limits for the population of the coordination spheres.