Notes. Synthesis and characterization of monocyclopentadienyl niobium derivatives. X-Ray crystal structure of di-µ-chloro-µ-oxo-bis[dichloro(η-trimethylsilylcyclo-pentadienyl)niobium(V)], [{Nb(η-C5H4SiMe3)Cl2}2(µ-O)(µ-Cl)2]

Abstract

[Nb(η-C₅H₄R)Cl₄][R = H (1) or SiMe₃(2)] are easily hydrolysed to give [{Nb(η-C₅H₄R)Cl₂}₂(µ-O)-(µ-Cl)₂][R = H (3) or SiMe₃(4)] and finally [{Nb(η-C₅H₄R)Cl₃(OH₂)}₂(µ-O)][R = H (5) or SiMe₃(6)]. The reduction of (1) and (2) with sodium amalgam in the presence of ligands allows isolation of [Nb(η-C₅H₄R)Cl₃L₂] and [Nb(η-C₅H₄R)Cl₂(CO)L₂](R = H or SiMe₃; L₂= 2PMe₃,2PMe₂Ph, or Ph₂PCH₂CH₂PPh₂) which have been characterized by magnetic measurements and i.r. and n.m.r. spectroscopy. The crystal structure of (4) has been determined: monoclinic, space group P2₁/n with a= 26.805(7), b= 7.310(2), c= 13.400(3)Å, β= 91.42(2)°, and Z= 4. The structure was refined to R= 0.063 for 2 539 observed reflections.