1,2,3,4,5-Cyclopentanepentayl, compd. with 1-[(1R)-1-[bis(3,5-dimethylphenyl)phosphino]ethyl]-2-[bis(4-methoxy-3,5-dimethylphenyl)phosphino]-1,2,3,4,5-cyclopentanepentayl, iron salt (1:1:1); s-3,5me-4meoph-xyl; (2S)-1-[(1S)-1-[BIS(3,5-DIMETHYLPHENYL)PHOSPHINO]ETHYL]-2-[BIS(4-METHOXY-3,5-DIMETHYLPHENYL)PHOSPHINO]FERROCENE; (s,s)-1-{1-[bis(3,5-dimethylphenyl)phosphino]ethyl}-2-[bis(4-methoxy-3,5-dimethylphenyl)phosphino]ferrocene; (S)-1-[(R)-2-Di-(4-methoxy-3,5-dimethylphenyl-phosphino)ferrocenyl]-ethyl-di-3,5-xylylphosphine