Chns 932 microanalyzer

All manipulations were carried
out under a dry argon atmosphere using Schlenk-tube and cannula techniques
or in a conventional argon-filled glovebox. Solvents were carefully
refluxed over the appropriate drying agents and distilled prior to
use: C₆D₆ and hexane (Na/K alloy), CDCl₃ (CaH₂), tetrahydrofuran (Na/benzophenone), and
toluene (Na). The starting materials [TaCp^RX₄] (Cp^R = η⁵-C₅Me₅, η⁵-C₅H₄SiMe₃;
X = Cl, Br) were prepared by following the reported procedure for
titanium,^{42 (link)} and the preparation of [Ta(η⁵-C₅HMe₄)Br₄] is detailed
in the Supporting Information along with
the molecular structure of [Ta(η⁵-C₅HMe₄)Br₄]. TaX₅ (X = Cl, Br), SiH₃Ph, and C₅HMe₄SiMe₃ were purchased
from Aldrich and were used without further purification. Azobenzene
and benzo[c]cinnoline were purchased from Alfa Aesar
and were used after sublimation. Microanalyses (C, H, N, S) were performed
with a LECO CHNS-932 microanalyzer. Samples for IR spectroscopy were
prepared as KBr pellets and spectra recorded on a PerkinElmer IR-FT
Frontier spectrophotometer (4000–400 cm^–1). ¹H and ¹³C NMR spectra were obtained by
using the Varian NMR spectrometers Unity-300 Plus, Mercury-VX, and
Unity-500 and reported with reference to solvent resonances. ¹H–¹³C gHSQC spectra were recorded using
a Unity-500 MHz NMR spectrometer operating at 25 °C.

All manipulations were carried
out under a dry argon atmosphere using Schlenk-tube and cannula techniques
or in a conventional argon-filled glovebox. Solvents were carefully
refluxed over the appropriate drying agents and distilled prior to
use: C₆D₆ and hexane (Na/K alloy), tetrahydrofuran
(Na/benzophenone), and toluene (Na). Starting materials [Ta(η⁵-C₅Me₅)R(μ-S)]₂ (R
= Cl, Me, CH₂Me, CH₂SiMe₃, C₃H₅, and Ph),^{19 (link)} and the
organomagnesium reagents [MgR₂(thf)₂] (R = p-MeC₆H₄CH₂, CH₂Ph)^{31 (link)} were synthesized according to published
procedures, and LinBu (1.6 M in hexane) was purchased
by Sigma-Aldrich and used without further purification. Hydrogen was
purchased from Linde. Microanalyses (C, H, N, and S) were performed
on a LECO CHNS-932 microanalyzer. Samples for IR spectroscopy were
prepared as KBr pellets and recorded on the PerkinElmer IR-FT Frontier
or Bruker FT-IR-ALPHA II spectrophotometers (4000–400 cm^–1). ¹H and ¹³C NMR spectra were
obtained by using Varian NMR System spectrometers: Unity-300 Plus,
Mercury-VX, and Unity-500, and reported with reference to solvent
resonances. ¹H–¹³C gHSQC were recorded
using the Unity-500 MHz NMR spectrometer operating at 25 °C.

Elemental analyses (C, H, N) were performed on a Leco CHNS-932 microanalyzer. IR spectra were acquired on diluted KBr pellets in a ThermoNicolet IR 200 spectrometer in the 4000–400 cm⁻¹ spectral region. Thermal analyses (TG/DTA) were performed on a TA Instruments SDT 2960 thermal analyzer in a synthetic air atmosphere (79% N₂/21% O₂) with a heating rate of 5 °C·min⁻¹.