7 research outputs found
Insertion and Substitution Chemistry at the Boron Fourth Position in Charge-Neutral Zwitterionic Tripodal Tris(methimazolyl)borate Ligands
A number of new charge-neutral zwitterionic tris(methimazolyl)borate
ligands have been synthesized, either by substitution of the dimethylamine
group in the adduct (dimethylamine)tris(methimazolyl)borane (<b>1</b>) or by insertion into its B–N(dimethylamine) bond
by an unsaturated Lewis base. Two new anionic ligands, (thiocyanato)tris(methimazolyl)borate
and (cyano)tris(methimazolyl)borate, have also been accessed by this
method
Insertion and Substitution Chemistry at the Boron Fourth Position in Charge-Neutral Zwitterionic Tripodal Tris(methimazolyl)borate Ligands
A number of new charge-neutral zwitterionic tris(methimazolyl)borate
ligands have been synthesized, either by substitution of the dimethylamine
group in the adduct (dimethylamine)tris(methimazolyl)borane (<b>1</b>) or by insertion into its B–N(dimethylamine) bond
by an unsaturated Lewis base. Two new anionic ligands, (thiocyanato)tris(methimazolyl)borate
and (cyano)tris(methimazolyl)borate, have also been accessed by this
method
Inter- versus Intramolecular Structural Manipulation of a Dichromium(II) Pacman Complex through Pressure Variation
The
effect of pressure on the intranuclear M···M
separation and intermolecular secondary interactions in the dinuclear
chromium Pacman complex [Cr<sub>2</sub>(L)](C<sub>6</sub>H<sub>6</sub>) was evaluated because this compound contains both a short Cr···Cr
separation and an exogenously bound molecule of benzene in the solid
state. The electronic structure of [Cr<sub>2</sub>(L)] was determined
by electron paramagnetic resonance spectroscopy, SQUID magnetometry,
and density functional theory calculations and shows a diamagnetic
ground state through antiferromagnetic exchange, with no evidence
for a Cr–Cr bond. Analysis of the solid-state structures of
[Cr<sub>2</sub>(L)](C<sub>6</sub>H<sub>6</sub>) at pressures varying
from ambient to 3.0 GPa shows little deformation in the Cr···Cr
separation, i.e., no Cr–Cr bond formation, but instead a significantly
increased interaction between the exogenous arene and the chromium
iminopyrrolide environment. It is therefore apparent from this analysis
that [Cr<sub>2</sub>(L)] would be best exploited as a rigid chemical
synthon, with pressure regulation being used to mediate the approach
and secondary interactions of possible substrates
Inter- versus Intramolecular Structural Manipulation of a Dichromium(II) Pacman Complex through Pressure Variation
The
effect of pressure on the intranuclear M···M
separation and intermolecular secondary interactions in the dinuclear
chromium Pacman complex [Cr<sub>2</sub>(L)](C<sub>6</sub>H<sub>6</sub>) was evaluated because this compound contains both a short Cr···Cr
separation and an exogenously bound molecule of benzene in the solid
state. The electronic structure of [Cr<sub>2</sub>(L)] was determined
by electron paramagnetic resonance spectroscopy, SQUID magnetometry,
and density functional theory calculations and shows a diamagnetic
ground state through antiferromagnetic exchange, with no evidence
for a Cr–Cr bond. Analysis of the solid-state structures of
[Cr<sub>2</sub>(L)](C<sub>6</sub>H<sub>6</sub>) at pressures varying
from ambient to 3.0 GPa shows little deformation in the Cr···Cr
separation, i.e., no Cr–Cr bond formation, but instead a significantly
increased interaction between the exogenous arene and the chromium
iminopyrrolide environment. It is therefore apparent from this analysis
that [Cr<sub>2</sub>(L)] would be best exploited as a rigid chemical
synthon, with pressure regulation being used to mediate the approach
and secondary interactions of possible substrates
Inter- versus Intramolecular Structural Manipulation of a Dichromium(II) Pacman Complex through Pressure Variation
The
effect of pressure on the intranuclear M···M
separation and intermolecular secondary interactions in the dinuclear
chromium Pacman complex [Cr<sub>2</sub>(L)](C<sub>6</sub>H<sub>6</sub>) was evaluated because this compound contains both a short Cr···Cr
separation and an exogenously bound molecule of benzene in the solid
state. The electronic structure of [Cr<sub>2</sub>(L)] was determined
by electron paramagnetic resonance spectroscopy, SQUID magnetometry,
and density functional theory calculations and shows a diamagnetic
ground state through antiferromagnetic exchange, with no evidence
for a Cr–Cr bond. Analysis of the solid-state structures of
[Cr<sub>2</sub>(L)](C<sub>6</sub>H<sub>6</sub>) at pressures varying
from ambient to 3.0 GPa shows little deformation in the Cr···Cr
separation, i.e., no Cr–Cr bond formation, but instead a significantly
increased interaction between the exogenous arene and the chromium
iminopyrrolide environment. It is therefore apparent from this analysis
that [Cr<sub>2</sub>(L)] would be best exploited as a rigid chemical
synthon, with pressure regulation being used to mediate the approach
and secondary interactions of possible substrates
The Effect of High Pressure on Polymorphs of a Derivative of Blatter’s Radical: Identification of the Structural Signatures of Subtle Phase Transitions
The effect of pressure
on the α and β polymorphs
of
a derivative of Blatter’s radical, 3-phenyl-1-(pyrid-2-yl)-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl, has been investigated using single-crystal
X-ray diffraction to maximum pressures of 5.76 and 7.42 GPa, respectively.
The most compressible crystallographic direction in both structures
lies parallel to π-stacking interactions, which semiempirical
Pixel calculations indicate are also the strongest interactions present.
The mechanism of compression in perpendicular directions is determined
by void distributions. Discontinuities in the vibrational frequencies
observed in Raman spectra measured between ambient pressure and ∼5.5
GPa show that both polymorphs undergo phase transitions, the α
phase at 0.8 GPa and the β phase at 2.1 GPa. The structural
signatures of the transitions, which signal the onset of compression
of initially more rigid intermolecular contacts, were identified from
the trends in the occupied and unoccupied volumes of the unit cell
with pressure and in the case of the β phase by deviations from
an ideal model of compression defined by Birch–Murnaghan equations
of state
The Effect of High Pressure on Polymorphs of a Derivative of Blatter’s Radical: Identification of the Structural Signatures of Subtle Phase Transitions
The effect of pressure
on the α and β polymorphs
of
a derivative of Blatter’s radical, 3-phenyl-1-(pyrid-2-yl)-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl, has been investigated using single-crystal
X-ray diffraction to maximum pressures of 5.76 and 7.42 GPa, respectively.
The most compressible crystallographic direction in both structures
lies parallel to π-stacking interactions, which semiempirical
Pixel calculations indicate are also the strongest interactions present.
The mechanism of compression in perpendicular directions is determined
by void distributions. Discontinuities in the vibrational frequencies
observed in Raman spectra measured between ambient pressure and ∼5.5
GPa show that both polymorphs undergo phase transitions, the α
phase at 0.8 GPa and the β phase at 2.1 GPa. The structural
signatures of the transitions, which signal the onset of compression
of initially more rigid intermolecular contacts, were identified from
the trends in the occupied and unoccupied volumes of the unit cell
with pressure and in the case of the β phase by deviations from
an ideal model of compression defined by Birch–Murnaghan equations
of state