Synthetic, reactivity, and structural studies on borylcyclopentadienyl complexes of titanium: New Cp-B titanocene complexes with C-B-Cl, C-B-O, and C-B-N bridges (Cp-B = eta(5)-C5H4B(C6F5)(2))

Lancaster, Simon J., Al-Benna, Sarah, Thornton-Pett, Mark and Bochmann, Manfred ORCID: https://orcid.org/0000-0001-7736-5428 (2000) Synthetic, reactivity, and structural studies on borylcyclopentadienyl complexes of titanium: New Cp-B titanocene complexes with C-B-Cl, C-B-O, and C-B-N bridges (Cp-B = eta(5)-C5H4B(C6F5)(2)). Organometallics, 19 (8). pp. 1599-1608. ISSN 0276-7333

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Abstract

The (borylcyclopentadienyl)titanium complex (Cp-B)TiCl3 (1; Cp-B = eta(5)-C5H4B(C6F5)(2)) reacts with LiC5H5 (LiCp), LiC5H4SiMe3 (LiCP'), and LiC9H7 (LiInd) to give the titanocene complexes (Cp-B)CpTiCl2 (2), (Cp-B)Cp'TiCl2 (3), and (Cp-B)(Ind)TiCl2 (4), respectively. In contrast to 1, which possesses piano stool geometry with an uncoordinated, trigonal-planar borg moiety, the -B(C6F5)(2) substituents in 2-4 act as intramolecular Lewis acids by coordinating to chloride ligands, with formation of B-Cl-Ti bridges that have relatively short B-Cl and elongated Ti-Cl bonds. The compounds are fluxional, with the -B(C6F5)(2) moiety switching rapidly from one chloride ligand to the other (2: Delta G(double dagger) = 37 kJ mol(-1) (200 K)). Recrystallization of 2 in the presence of traces of moisture afforded (Cp-B)CpTi(mu-OH)Cl (5), with a rigid B-O-Ti chelate arrangement. Treatment of 1 with 1 or 2 equiv of LiHNCMe3 gives the binuclear titanium imido complexes [(Cp-B)TiCl(mu-NCMe3)](2) (7) and [(Cp-B)TiCl(mu-NCMe3). H2NCMe3](2) (8), respectively. These complexes are based on Ti2N2 rings but show no boron-imide interactions. In contrast, the reaction of 2 with LiNHCMe3 affords (Cp-B)CpTi(mu-NHCMe3)Cl (9), which exhibits a constrained-geometry type Cp-B-N arrangement. The crystal structures of 4, 5, 8, and 9 have been determined.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Chemistry (former - to 2024)
UEA Research Groups:	Faculty of Science > Research Groups > Synthetic Chemistry (former - to 2017) Faculty of Science > Research Groups > Chemistry of Materials and Catalysis Faculty of Science > Research Groups > Chemistry of Light and Energy
Depositing User:	Rachel Smith
Date Deposited:	16 Jun 2011 15:03
Last Modified:	24 Sep 2024 10:27
URI:	https://ueaeprints.uea.ac.uk/id/eprint/32747
DOI:	10.1021/om9909744

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