Synthesis of Racemic Aminoalkylferrocenyldichlorophosphanes and -dialkylphosphonites and Their Conversion to Primary Phosphanes

Abstract

The dichlorophosphanyl-substituted ferrocene complexes 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-3-diphenylphosphanylferrocene (2a) and 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-3,1′-bis(diphenylphosphanyl)ferrocene (2b) have been prepared by the reaction of phosphorus trichloride with the corresponding lithiated aminoalkylferrocene precursors. The crystal structure of 2a reveals a short N···P distance, which is suggestive of a weak N→P dative bond. Using diethyl chlorophosphite instead of phosphorus trichloride as electrophile gave 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3-diphenylphosphanylferrocene (3a) and 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3,1′-bis(diphenylphosphanyl)ferrocene (3b), respectively. The latter was converted to the corresponding dimethoxy compound 4b by reaction with methanol. Crystal structures of 3 and 4b have been determined. Reduction of 2, 3, and 4b with LiAlH4 or LiAlH4/SiMe3Cl yielded the primary phosphanes 1-diphenylphosphanyl-2-N,N-dimethylaminomethyl-3-phosphanylferrocene (5a) and 1,1′-bis(diphenylphosphanyl)-2-N,N-dimethylaminomethyl-3-phosphanylferrocene (5b). The latter was also structurally characterized by X-ray diffraction.

Homotrinuclear ruthenium(ii) and rhodium(i) complexes of redox-active tris(ferrocenyl)arene-based tris-phosphanes

“…14,15 Constructing multi-ferrocene systems is usually motivated by the redox properties of the individual ferrocene moieties which, when assembled, can add up to more than the mere sum of its parts. 16,17 Motivated by the prominence of C 3 -symmetry in modern-day ligand design and the potential to exploit the use of three ferrocenyl groups for redox-switchable catalysis (RSC), we have built upon our previous works on ferrocenylphosphanes [18][19][20][21][22][23][24][25][26] and their applications in RSC [27][28][29] and reported a new family of tris-phosphanes (1a-d, Scheme 1) based on a redox-active, C 3 -symmetric tris(ferrocenyl)arene backbone. By incorporating an electronwithdrawing (b and c) or a tris-benzylic arene core (d), the electrochemical response as well as more subtle inuences on the coordination behaviour of the corresponding phosphanes become adjustable.…”

Synthesis of 1,1′,2-Trisubstituted Aryl-Based Ferrocenyl Phosphines as Precursors for Immobilized Ligands

“…Ferrocene has proved to be a versatile substituent for phosphanes because of its rich chemistry, stability, and redox properties and thus plays a significant role as a backbone or substituent in ancillary ligands . Phosphorus-bearing ferrocenes allow the design of ligands with various electronic and steric properties in order to increase their efficiency in catalysis. , Some chiral ferrocenyl bis-phosphines were also immobilized and their activity was tested: e.g., in the hydroxylation of benzene and ring-closing metathesis, Ir-catalyzed imine hydrogenation, Pd-catalyzed hydrogenation of ethyl nicotinate, and Rh-catalyzed hydrogenation of olefins…”

“…A number of unsymmetrically 1,1′-substituted ferrocene derivatives have been reported and their properties as ligands studied . Their preparation relies on stepwise transmetalation/functionalization reactions or halogen exchange on suitable symmetrically 1,1′-substituted precursors .…”