Trend‐Analysis of Solid‐State Structures: Low‐Energy Conformational ‘Reactions’ Involving Directed and Coupled Movements in Half‐Sandwich Compounds [CpFe(CO){C(=O)R}PPh 3 ]

摘要

Trends in solid‐state structures were used to identify preferred intramolecular movements in half‐sandwich compounds [CpFe(CO){C(=O)R}PPh 3 ]. Three weak interactions were analyzed: 1)?the CH/π donor–acceptor interaction of phenyl rings in the PPh 3 ligand, 2)?the Ph PPh3 face‐on Cp stabilization, and 3)?the hydrogen bond between the oxygen atom of the acyl group and an ortho ‐C?H bond of one of the PPh 3 phenyl rings. Clockwise and counter‐clockwise rotations established directed and coupled movements of the PPh 3 ligand, the acyl group, and the phenyl rings within the PPh 3 ligand. Sandwich break : Low‐energy directed and coupled movements within half‐sandwich compounds [CpFe(CO){C(=O)R}PPh 3 ] are identified through a trend analysis of their solid‐state structures. Ph edge and Ph face of the PPh 3 ligand, connected by a weak CH/π interaction, do not move independently but concertedly. Although in the ‘reaction’ JIDLUD→FIHTUL Ph edge rotates counter‐clockwise (c‐clw) around the C i ?P bond, Ph face rotates clockwise (clw) to maintain the stabilizing CH/π interaction.