Di- and highernuclear metallocenes
Fixing cyclopentadienyl-metal fragments at bridging ligands yields various dinuclear diamagnetic and paramagnetic metallocenes which may exist as syn and anti isomers. Highnuclear metallocenes tend to form rings. Up to 17-membered rings have been established [see publication list refs. 128, 140]; Figure 1 shows the 7-membered ring [see ref. 118]. For 18 see refs. 97, 99, 100, 111, 113, 125, 138; for 19 see refs. 50, 104, 121,122, 134, 136; for 20 see ref. 96; for 21 see ref. 106; for 22 see ref. 124. Trinuclear metallocenes see refs. 99, 103, 113, 138; for highernuclear metallocenes see refs. 97, 118, 128, 140.