Selective Lithiation and Phosphane-Functionalization of [(η7-C7H7)Ti(η5-C5H5)] (Troticene) and Its Use for the Preparation of Early-Late Heterobimetallic Complexes

The cycloheptatrienyl-cyclopentadienyl sandwich complex [(η7-C7H7)Ti(η5-C5H5)] (troticene) can be dilithiated (once at each ring) or selectively monolithiated, either at the seven- or five-membered ring, depending on the reaction conditions. Treatment of the resulting lithiotroticenes with ClPPh2 afforded the corresponding troticenyl-phosphanes [(η7-C7H6PPh2)Ti(η5-C5H4PPh2)] (1), [(η7-C7H6PPh2)Ti(η5-C5H5)] (2), or [(η7-C7H7)Ti(η5-C5H4PPh2)] (3). The use of nBuLi/N,N′,N′,N′′,N”-pentamethyldiethylenetriamine (pmdta) allowed us to isolate the lithium complexes [(η7-C7H6Li)Ti(η5-C5H4Li)]·pmdta (4) and [(η7-C7H7)Ti(η5-C5H4Li)]·pmdta (5), which were structurally characterized by X-ray diffraction analyses. Reaction of the monophosphane 3 with Mo(CO)6 and [(tht)AuCl] (tht = tetrahydrothiophene) afforded the heterobimetallic complexes [(3)Mo(CO)5] (6) and [(3)AuCl] (7) and also the trimetallic species [(3)2AuCl] (8). The reaction of trans-[PtCl2(SEt2)2] with the diphosphane 1 led to the formation of cis-[(1)PtCl2] (9), whereas the complexes trans-[(2)2PtCl2] (10) and trans-[(3)2PtCl2] (11) were isolated by reaction of two equivalents of the monophosphanes 2 and 3 with trans-[PtCl2(SEt2)2]. The X-ray crystal structures of 6−11 are also reported.