Heterocycle-containing niobocene derivatives from hydride–niobocene complexes: X-ray molecular structure of [Cp′2Nb(CNXylyl)2][I3] and [Cp′2Nb(H)(P(OMe)3)] · (bzta)′-NH2 [(bzta)′-NH2 = 2-amino-6-methylbenzothiazole]

The reaction under thermal conditions of [Cp′2Nb(H)3] (1), Cp′ = η5-C5H4SiMe3, with benzothiazole heterocycles, namely 2-aminobenzothiazole, bzta-NH2, 2-hydroxybenzothiazole, bzta-OH, 2-mercaptobenzothiazole, bzta-SH, benzoxazole, namely 2-mercaptobenzoxazole, bzoa-SH, and triazines, namely 1,3,5-triaminetriazine, 1,3,5-trihydroxytriazine, 1,3,5-trimercaptotriazine, (C3N3)-1,3,5-(XH)3, X = NH, O, S, yields a new family of niobocene complexes [Cp′2Nb(κ2-X,S-Xbzta)], X = NH (2), O (3), S (4), [Cp′2Nb(κ2-S,N-Sbzoa)] (5) and [(Cp′2Nb)3(κ2-X,N-X3C3N3)], X = NH (6), X = O (7), X = S (8). In the same way, the thermal treatment of complex [Cp′2Nb(H)(CNXylyl)] (9), Xylyl = C6H4-2,6-Me2, with bzta-SH, bzoa-SH and (C3H3)-1,3,5-(SH) affords the complexes [Cp′2Nb(κ1-S-Sbzta)(CNXylyl)] (10), [Cp′2Nb(κ1-S-Sbzoa)(CNXylyl)] (11) and [{Cp′2Nb(CNXylyl)}3(κ1-S-S3C3N3)] (12). The reaction of compound 10 with an excess of MeI in toluene at room temperature leads to the ionic compound [Cp′2Nb(CNXylyl)2][I3] (15), which contains two coordinated CNXylyl ligands and a non-coordinated I3− counteranion. All complexes were characterized by spectroscopic methods and the molecular structure of [Cp′2Nb(CNXylyl)2][I3] (15) and [Cp′2Nb(H)(P(OMe)3)] · (bzta)′-NH2 (14), an adduct of the heterocycle with the hydride–niobocene, have been determined by X-ray molecular studies.

Graphical abstractNew niobocene complexes containing benzothiazole heterocycles, namely 2-aminobenzothiazole, bzta-NH2, 2-hydroxybenzothiazole, bzta-OH, 2-mercaptobenzothiazole, bzta-SH, benzoxazole, namely 2-mercaptobenzoxazole, bzoa-SH, and triazines, namely 1,3,5-triaminetriazine, 1,3,5-trihydroxytriazine, 1,3,5-trimercaptotriazine, (C3N3)-1,3,5-(XH)3, X = NH, O, S, have been prepared and spectroscopically characterised. The crystal structures of [Cp′2Nb(CNXylyl)2][I3] and [Cp′2Nb(H)(P(OMe)3)]. (bzta)′-NH2 [(bzta)′-NH2 = 2-amino-6-methylbenzothiazole] (Cp′ = η5-C5H4SiMe3) have been determinedFigure optionsDownload full-size imageDownload as PowerPoint slide