Compounds of the formula (I) and (Ia) in the form of racemates, mixtures of diastereomers or in essentially enantiomerically pure form, (I), (Ia), where R is hydrogen, C1-C8alkyl, C5-C12cycloakyl, phenyl or phenyl substituted by from 1 to 3 C1-C4alky or C1-C4alkoxy groups; n is 0 or an integer from 1 to 4 and R1 are identical or different subtitutuents selected from the group consisting of C1-C4alkyl, C1-C4fluoroalkyl and C1-C4alkoxy; X1 and X2 are each, indenpendently of one another, secondary phosphino; T is C6-C20arylene or C3-C16heteroarylene; and X2 is bound in the ortho position relative to the T-cyclopentadienyl bond. The compounds are ligands for complexes of metal selected from transition groups (I) and (VIII) of the Periodic Table of the Elements, and these metal complexes are valuable catalysts for the asymmetric addition of hydrogen, boron hydrides or silanes onto carbon-carbon or carbon-heteroatom multiple bonds in prochiral organic compounds or the asymmetric addition of carbon nucleophiles or amines onto allyl compounds.