Facile Arene Ligand Exchange in p-Cymene Ruthenium(II) Complexes of Tertiary P-Chiral Ferrocenyl Phosphines

Abstract

Half-sandwich arene–metal complexes are commonly used for specific applications. Herein, we report facile arene ligand exchange reactions of two ruthenium(II) complexes of tertiary P-stereogenic ferrocenyl phosphines. By mild photochemical activation, the displacement of p-cymene and subsequent tethering by η6-coordination of the terminal phenyl ring of a biphenylyl-substituted ferrocenyl phosphine were enabled. Furthermore, the spontaneous p-cymene displacement in a 2-methoxyphenyl-containing ferrocenyl phosphine and ensuing coordination of the ligand as a P,O chelate were examined. For both reactions, theoretical calculations of the general course of the reaction confirmed the experimental findings. The ease of the controlled arene displacement reported here can offer new pathways for the synthesis and design of novel tailor-made catalysts.

Triple the fun: tris(ferrocenyl)arene-based gold(i) complexes for redox-switchable catalysis

“…[75][76][77] Adduct [1a(BH 3 ) 3 ] was found to crystallise with crystallographic C 3 symmetry (space group R 3, Fig. 1) and compares well (Table S5 †) to structural parameters of similar ferrocenyl-phosphane boranes described by us 78 as well as byŠtěpnička and co-workers. 79 Recently we reported the capability of 1c to bind coinage metal ions in a tridentate trigonal planar coordination mode; 43 now we have turned our focus to potential trinuclear gold(I) complexes of 1a-c.…”

Redox‐Switchable Transfer Hydrogenations with P‐Chiral Dendritic Ferrocenyl Phosphine Complexes

“…Recently, we prepared three P-stereogenic ferrocenyl phosphine boranes 2a-c-ML with a 4-methoxyphenyl substituent in the 1′-position of the ferrocenyl group (Scheme 1). [67,68] In these monomeric (non-dendritic) ligands (ML) the 4-methoxyphenyl substituent serves to mimic the phenol linker which is needed in immobilization reactions. The P-stereogenic ferrocenyl phosphine boranes 2a-c-ML were synthesized with excellent enantiopurity (> 95 % ee in all cases) and subsequent borane-deprotection by heating in diethylamine, followed by reaction with [{Ru(p-cymene)Cl 2 } 2 ], yielded the monomeric ruthenium complexes 3a-c-ML-Ru.…”

Unusual Racemization of Tertiary P‐Chiral Ferrocenyl Phosphines

“…The P ‐stereogenic ferrocenyl phosphine boranes 1 a – c were successfully synthesized from an unsymmetrically disubstituted 1,1′‐ferrocene and three methyl (phenyl)phosphinite boranes (Scheme ) which were accessible via an (−)‐ephedrine‐based oxazaphospholidine borane complex . This auxiliary‐based methodology provides a convenient strategy for a stepwise preparation of tertiary P ‐stereogenic phosphines (>95 % ee in all cases).…”

“…The first indications that made us investigate the phosphorus‐based stereochemistry of these ligands in detail were the single crystal X‐ray crystallographic analyses of their corresponding ruthenium(II) complexes 3 a – c (Figure ). In repeated attempts, we continuously found that complexes 3 a and 3 b crystallize in the achiral space group P indicating the presence of racemates.…”

“… Molecular structure of 3 b (top left, P ), 3 a (bottom left, P ) and 3 c (right, P 2 1 ) in the solid state. Ellipsoids at 50 % probability; hydrogen atoms are omitted for clarity.…”