Synthesis and Structure of the First [1]Boratitanocenophanes

Abstract

This paper presents two methods for the synthesis of the first [1]boratitanocenophanes. The novel biscyclopentadienylborane [(Me3Si)2NB(C5H5)2], the dilithio salt Li2[(Me3Si)2NB(C5H4)2] (1) of which was characterized by multinuclear NMR methods, was prepared in situ, and served as starting material for several [1]boratitanocenophanes. [Cl2Ti{(C5H4)2BN(SiMe3)2}] (2) was obtained in high yield by a convenient one‐pot synthesis starting from 1 and [TiCl3(thf)3], followed by oxidation with PbCl2. The highly reactive [(Me2N)2Ti{(C5H4)2BN(SiMe3)2}] (3) was obtained by the reaction of [(Me3Si)2NB(C5H5)2], prepared in situ, with Ti(NMe2)4and converted into the chloro derivatives [(Me2N)ClTi{(C5H4)2BN(SiMe3)2}] (4) and [Cl2Ti{(C5H4)2BN(SiMe3)2}] (2) by treatment with one or two equivalents of a suitable diaminochloroborane. All [1]boratitanocenophanes were characterized in solution by multinuclear NMR spectroscopy, and in addition the structure of 2 in the crystalline state was determined by a single‐crystal X‐ray study.

Piperidino Substituted [1]Borametallocenophanes. Synthesis, Reactivity, and Structure

“…The geometry of the metal centres is almost identical; a tilt angle α of 65.5 • , a deformation angle δ of 120.9 • , an average distance between the metal centre and the Cp centroids of 2.173Å and Zr-Cl distances of 2.469(1) and 2.470(1)Å are found in 4, and hence, are very similar to the reported crystal structures of known [1]borametallocenophanes [2]. The differences found at the bridging moity can be explained by the higher coordination number of boron (four-versus three-coordinated).…”

“…In the past years we [2,11] and others [12] investigated the impact of aminoborylene-bridged [n]borametallocenophanes (n = 1, 2) and related constrained geometry complexes [13] towards their catalytic activity (Fig. 1, type I and II).…”

“…The incorporation of a boron bridge has been associated with a number of beneficial characteristics, e. g. improved catalytic activity [2]. Furthermore, the potential of the Lewis acidic boron centre for an intramolecular activation is envisaged [3].…”

“…Preliminary results on the [2]borametallocenophanes have indicated a tremendous increase in the catalytic activity combined with the isolation of a polymeric material of very high molecular weight [2c]. Here we report the synthesis and structure of piperidino-substituted [1]borametallocenophanes of zirconium and titanium.…”

Electropolymerization of Polysilanes with Functional Groups

“…The chemical shift δ=4.9-5.1, 5.8 and 1.5 on the 1 H-NMR spectrum of EPS3 (Fig.9) correspond to the primary, secondary and tertiary H of the allyl group 13 . The spectral peak at δ=5.5 and 6.0 belongs to the H of Cp group attaching to Zr elements 24,25 .…”