Metallacyclopentadienes: structural features and coordination in transition metal complexes

Abstract

Results of structural studies of polynuclear transitionResults of structural studies of polynuclear transition metal complexes containing the metallacyclopentadiene fragment metal complexes containing the metallacyclopentadiene fragment are overviewed. The structural features of the complexes in are overviewed. The structural features of the complexes in relation to the nature of the substituents in the organic moiety of relation to the nature of the substituents in the organic moiety of the metallacycles, the nature of the transition metals and their the metallacycles, the nature of the transition metals and their ligand environment are analysed. The main structural character-ligand environment are analysed. The main structural characteristics corresponding to different modes of coordination of metal-istics corresponding to different modes of coordination of metallacyclopentadienes to one or two additional metal centres are lacyclopentadienes to one or two additional metal centres are revealed. The bibliography includes 154 references revealed. The bibliography includes 154 references. .

Synthesis and Characterization of Heterobimetallic Tantalum–Rhodium and Tantalum–Iridium Complexes Connected by a Tantalacyclopentadiene Fragment

“…[13] Because of the high coordination number for the Ta atom in complex 3 compared with that of 2 , the bond lengths of Ta–C(1) and Ta–C(4) (2.225(11) and 2.186(12) Å) are longer than those of complex 2 , while they are consistent with other metallacyclopentadiene‐bridged dinuclear Ta complexes. [14] The bond lengths of the C‐atom linkages in the tantalacyclopentadiene, C(1)–C(2), C(2)–C(3), and C(3)–C(4) bonds, are similar, and equalization of the C–C bonds agree with other dinuclear metallacyclopentadiene complexes …”

Some unusual reactions of metal carbonyls with (Z)-1-ferrocenyltelluro-1-ferrocenyl-4-ferrocenyl-1-buten-3-yne

“…The ferracyclopentadiene ring is in an eclipsed conformation which is fairly uncommon compared to the common staggered conformation, found in most of the complexes. 32 Position 5 of the ferracyclopentadiene ring is occupied by the ferrocenyl group, whereas positions 2 and 3 are used in a ve membered-lactone ring formation. One of the carbon atoms of the lactone ring, present adjacent to position 3 of the ferracyclopentadiene unit, is substituted by the ferrocenyl group and is coordinated with another Fe(CO) 3 unit, which in turn is attached to the diene bonded Fe(CO) 2 unit through a direct Fe-Fe bond (Fe(2)-Fe(3) ¼ 2.753(8) Å).…”

Transmetalation Reactions of Aromatic Dilithionickelole: Synthesis of Heterobimetallic Complexes Featuring Metalloles as Diene Ligands

“…On the other hand, bimetallic complexes bearing a metallacyclopentadiene as π ligand are most commonly synthesized through metal-mediated oxidative cyclometallation of alkynes, [7,8] which requires variable oxidation states of the metal centers and thus is not feasible for main-group and rare-earth metals. As a result, metallacyclopentadienes of Mg, Sc and Lu have never been employed as π ligands for transition metals.…”