Structure and Properties of the Macrocyclic Tridentate Ferrocenylphosphine Ligand (−PhPC₅H₄FeC₅H₄−)₃

Abstract

Isolation and characterization were carried out for a novel tridentate ferrocenylphosphine macrocycle, (−PhPC5H4FeC5H4−)3, as follows. A photolytic ring-opening reaction of PPh-bridged [1]ferrocenophane in ether gave a mixture of its oligomers. After their sulfurization, GPC separation of low-molecular-weight species afforded two isomers of a macrocyclic trimer, 1,1′′:1′,1′′′′:1′′′,1′′′′′-tris(phenylthiophosphinidene)tris(ferrocene), in which three 1,1′-ferrocenediyl units and three P(S)Ph groups were alternately linked to form a macrocyclic ring. Although yields of both isomers were low (17% in total), they were successfully desulfurized in good yields without configurational inversion at their phosphorus centers by treatment with MeOTf/P(NMe2)3 (OTf = CF3SO3), to give the respective tridentate macrocyclic phosphine ligands. The molecular structure of one isomer (C 3 isomer) with C 3 symmetry was determined by X-ray analysis, while the other was identified as the C s isomer on the basis of 1H, 13C, and 31P NMR data. When the C 3 isomer was heated in toluene at around 80 °C, it isomerized gradually but almost completely to the C s isomer with the activation energy ΔG 350 ⧧ = 26.2 ± 0.6 kcal mol−1. The reaction of AgOTf with the C 3 isomer in CH2Cl2 gave a mononuclear silver complex in which the C 3 isomer encircled the Ag+ ion as a tridentate ligand. To our surprise, a similar reaction using the C s isomer gave the same silver complex as above, indicating that a facile conversion of the C s isomer to the C 3 isomer took place upon coordination to the Ag+ ion at room temperature.

Silver(i) complexes with 1′-(diphenylphosphino)-1-cyanoferrocene: the art of improvisation in coordination

“…Because of a d 10 valence shell configuration, soft 1 silver (I) ions have no stereochemical preference due to the lack of ligand field stabilization. As a result, the coordination geometry of Ag(I) complexes is determined by an interplay of electrostatic and steric factors and is, therefore, difficult to predict.…”

Phosphines and related C–P bonded compounds

“…These have now been separated, following sulfurization and desulfurization steps, to afford two configurational isomers of the macrocyclic trimer (152). 314 The reaction of (S p -)-2-(diphenylphosphino)ferrocenecarboxylic acid with carbodiimide reagents has been investigated. Under neutral conditions, the reaction with N,N 0 -dicyclohexylcarbodiimide affords the urea (153), whereas under basic conditions, the acid anhydride (154) is formed.…”

Host‐Guest Interactions by Metal‐to‐Metal Dative Bonding: Recognition of Ruthenocene by a Metallo‐Host

“…Metallocenes with a group 8 transition metal atom have been widely studied due to their chemical versatilities and five‐hold symmetrical sandwich‐type structures 4. Taking advantages of their structural characteristics, a number of excellent examples of molecular architectures have been reported such as foldamers,4c molecular machines,4a macrocycles,4b,4d,4f and supramolecular assemblies 4e,4f. Besides, their unique redox property also enhances the functionality of metallocene‐based molecular architectures 5,6.…”