Gyroscopes and the chemical literature: 1852–2002

A brief history of mechanical gyroscopes and their applications is followed by a summary of properties that are desirable in molecular gyroscopes. Molecules to which the descriptor gyroscope has been applied are then reviewed through early 2002. Syntheses as well as structural and dynamic properties of the macrocyclic platinum complexes trans  -(Cl)(C6F5)Pt(PPh2(CH2)2n+2P⎴ Ph2) (n = 4, 5, 6, 8, 9), in which a single methylene chain spans the trans phosphorus atoms, are subsequently analyzed. No part of the Cl-Pt-C6F5 moiety can rotate through the macrocycle when it consists of 13 atoms; however, the chloride ligand can pass through macrocycles of ≥15 atoms, and the pentafluorophenyl ligand through macrocycles of ≥21 atoms. Analogous complexes in which two methylene chains span the trans phosphorus atoms are also discussed.