Dichlorido[(S,RS)‐1‐diphenylphosphino‐2‐(ethylsulfanylmethyl)ferrocene]palladium(II)

The reaction of enantiomerically pure planar chiral ferrocene phosphine thioether with bis(acetonitrile)dichloridopalladium yields the title square‐planar mononuclear palladium complex as an enantiomerically pure single diastereoisomer, [PdFe(C₅H₅)(C₂₀H₂₀PS)Cl₂]. The planar chirality of the ligand is retained in the complex and fully controls the central chirality on the S atom. The absolute configuration, viz. S for the planar chirality and R for the S atom, is unequivocally determined by refinement of the Flack parameter.     

Role of the conformation in the reactivity of 1,3-diphosphapropenes

The symmetrical and unsymmetrical 1,3-diphospha-propenes 3 and 4 were obtained from the corresponding diposphiranes 1 and 2 . The chemical behavior of these compounds has been studied. Phosphonium-phosphaalkenes 7a and 10a have been obtained in the reactions with aluminium trichloride. Whereas the symmetrical diphosphaallene 13 can be obtained by reaction of 1 or 3 with lithio compounds, the unsymmetrical diphosphaalene 14 cannot be prepared by a similar route. Reduction of 3a and 4a (obtained with a different conformation) by lithium aluminum hydride afforded phosphino-phosphaalkenes 17a and 18a (with a similar conformation); further dehydrochlorination with amines led to the symmetrical and unsymmetrical diphosphaalenes 13 and 14 , respectively. The formation of allenes strongly depends on the conformation of the starting diphosphapropenes.