Notes. Synthesis and characterization of monocyclopentadienyl niobium derivatives. X-Ray crystal structure of di-µ-chloro-µ-oxo-bis[dichloro(η-trimethylsilylcyclo-pentadienyl)niobium(<scp>V</scp>)], [{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.