Synthesis and structure of aminobis(η1-cyclopentadienyl)boranes and related compounds

Amino(diorganyl)boranes of the type R2NB(η1-CxHy)2 R=various ligands, CxHy=C5H5 (cyclopentadienyl), C9H7 (indenyl), C13H9 (fluorenyl) were recently reported as ligands in corresponding [1]borametallocenophanes of the Group IV metals Ti, Zr, and Hf. Several of those ligands including bis(cyclopentadienyl)boranes, cyclopentadienyl(indenyl)boranes, and difluorenylboranes such as iPr2NB(η1-C5H5)2 (7), iPr2NB(η1-C5H5)(η1-C9H7) (12), and Me2NB(η1-C13H9)2 (13), were obtained in very high yields and fully characterised. All compounds besides 13 show the expected presence of different constitutional isomers. Compound 7 was chosen as a representative example to assign all isomers by NMR methods. The structures of 12 (one isomer) and 13 in the solid state were determined by X-ray diffraction methods.