[2]Borametallocenophanes of Group 4 Metals: Synthesis and Structure

Abstract

We report a series of [2]borametallocenophanes of Ti, Zr, and Hf with various ligand systems. The ligands have been synthesized in high yields starting from 1,2-dibromo-1,2-bis(dimethylamino)diborane(4) upon reaction with Na[C5H5] and Li[C13H9], respectively. All compounds were fully characterized by multinuclear NMR spectroscopy and, for selected examples, by X-ray analysis.

Difluorenyl[2]borametallocenophanes of Group 4 Metals: Synthesis and Structure

“…In 1994 Nöth et al described the synthesis of 1,2‐bis(dimethylamino)‐1,2‐di‐η 1 ‐indenyldiborane(4)12 and 1,2‐bis(dimethylamino)‐1,2‐di‐η 1 ‐fluorenyldiborane(4) ( 2 )10 starting from 1,2‐dichloro‐1,2‐bis(dimethylamino)diborane(4) and Li[C 9 H 7 ] or Li[C 13 H 9 ]. According to this and our previously published method for the preparation of (Me 2 N) 2 B 2 (η 1 ‐C 5 H 5 ) 2 13 and (Me 2 N) 2 B 2 (η 1 ‐C 5 H 5 )(η 1 ‐C 13 H 9 ),6 we prepared the ligand precursors from 1,2‐dibromo‐1,2‐bis(dimethylamino)diborane(4) ( 1 ) in good yields (Scheme ).…”

“… Schematic representation of the influence of the bridging moiety on the tilt angle in cyclopentadienyl (Cp, C 5 H 4 )/fluorenyl (Flu, C 13 H 8 ) zirconocenophanes (a, b;5 c, d;6 e [this work]). …”

Catalytic Activity of [2]Borametallocenophanes

“…Polymerization catalysts were prepared according to literature procedures: [(Me 2 N) 2 B 2 (η 5 ‐C 5 H 4 ) 2 M Cl 2 ] [ M = Ti ( 1 ), Zr ( 2 ), Hf ( 3 )],21 [(Me 2 N) 2 B 2 (η 5 ‐C 5 H 4 )(η 5 ‐C 13 H 8 ) M Cl 2 ] [ M = Zr ( 4 ), Hf ( 5 )],22 [(Me 2 N) 2 B 2 (η 5 ‐C 5 H 4 )(η 5 ‐C 29 H 36 ) M Cl 2 ] [ M = Zr ( 6 ), Hf ( 7 )],24 [(Me 2 N) 2 B 2 (η 5 ‐C 13 H 8 ) 2 M Cl 2 ] [ M = Zr ( 8 ), Hf ( 9 )],23 [(Me 2 N) 2 B 2 (η 5 ‐C 29 H 36 ) 2 ZrCl 2 ] ( 10 ) 24. MAO, ethylene, and 1‐hexene were obtained commercially and used without further purification.…”

Organic Chemistry: A. Pfaltz Awarded / Molecular Recognition: J. Rebek Honored / Inorganic Chemistry: Prize to H. Braunschweig

“…Investigations into their electronic structure and reactivity open up applications in organic synthesis and catalysis and in materials science. He recently reported in Angewandte Chemie on the intramolecular activation of a disila[2]molybdenumocenophanedihydride for the synthesis of a [1],[1]metalloarenophane3a and in Chemistry—A European Journal on [2]borametallocenophanes of Group 4 metals 3b …”