3 research outputs found
Structural Variations in the Dithiadiazolyl Radicals <i>p</i>‑ROC<sub>6</sub>F<sub>4</sub>CNSSN (R = Me, Et, <sup><i>n</i></sup>Pr, <sup><i>n</i></sup>Bu): A Case Study of Reversible and Irreversible Phase Transitions in <i>p</i>‑EtOC<sub>6</sub>F<sub>4</sub>CNSSN
The 4′-alkoxy-tetrafluorophenyl
dithiadiazolyls, ROC<sub>6</sub>F<sub>4</sub>CNSSN [R = Me (<b>1</b>), Et (<b>2</b>), <sup><i>n</i></sup>Pr (<b>3</b>), <sup><i>n</i></sup>BuÂ(<b>4</b>)] all adopt <i>cis-oid</i> dimers in the solid state. The methoxy derivative <b>1</b> adopts a Ï€-stacked AA’AA’ motif, whereas
propoxy
(<b>3</b>) and butoxy (<b>4</b>) derivatives exhibit an
AA’BB’ stacking. The ethoxy derivative (<b>2</b>) is polymorphic. The α-phase (<b>2α</b>) adopts
an AA’BB’ motif comparable with <b>3</b> and <b>4</b>, whereas <b>2β</b> and <b>2γ</b> are reminiscent of <b>1</b> but combine a mixture of both
monomers and dimers in the solid state. The structure of <b>2β</b> exhibits <i>Z</i>’ = 6 with two dimers and two
monomers in the asymmetric unit but undergoes a thermally induced
phase transition upon cooling below −25 °C to form <b>2γ</b> (<i>Z</i>’ = 14) with six dimers
and two monomers in the asymmetric unit. The transition is associated
with both rotation and translation of the dithiadiazolyl ring. Detailed
differential scanning calorimetry and variable temperature powder
X-ray diffraction studies coupled with SQUID magnetometry have been
used to show that <b>2α</b> converts irreversibly to <b>2β</b> upon heating and that <b>2β</b> and <b>2γ</b> interconvert through a reversible phase transition
with a small thermal hysteresis in its magnetic response
Structure and Bonding of the Manganese(II) Phosphide Complex (<i>t</i>-BuPH<sub>2</sub>)(η<sup>5</sup>-Cp)Mn{μ-(<i>t</i>-BuPH)}<sub>2</sub>Mn(Cp)(<i>t</i>-BuPH<sub>2</sub>)
Rather than achieving bis-deprotonation of the phosphine,
reaction
of Cp<sub>2</sub>Mn (Cp = cyclopentadienyl) with <i>t</i>-BuPH<sub>2</sub> at room temperature yields monodeprotonation of
half of the available phosphine in the product (<i>t</i>-BuPH<sub>2</sub>)Â(η<sup>5</sup>-Cp)ÂMnÂ{μ-(<i>t</i>-BuPH)}<sub>2</sub>MnÂ(Cp)Â(<i>t</i>-BuPH<sub>2</sub>) (<b>1</b>). This complex comprises a MnÂ(II) phosphide and is a dimer
in the solid state, containing a Mn<sub>2</sub>P<sub>2</sub> diamond
core. Consistent with the observation of a relatively short intermetal
distance of 2.8717(4) Ã… in <b>1</b>, DFT analysis of the
full structure points to a singlet ground state stabilized by a direct
Mn–Mn single bond. This is in line with the diamagnetic character
of <b>1</b> and an 18-electron count at Mn
Structure and Bonding of the Manganese(II) Phosphide Complex (<i>t</i>-BuPH<sub>2</sub>)(η<sup>5</sup>-Cp)Mn{μ-(<i>t</i>-BuPH)}<sub>2</sub>Mn(Cp)(<i>t</i>-BuPH<sub>2</sub>)
Rather than achieving bis-deprotonation of the phosphine,
reaction
of Cp<sub>2</sub>Mn (Cp = cyclopentadienyl) with <i>t</i>-BuPH<sub>2</sub> at room temperature yields monodeprotonation of
half of the available phosphine in the product (<i>t</i>-BuPH<sub>2</sub>)Â(η<sup>5</sup>-Cp)ÂMnÂ{μ-(<i>t</i>-BuPH)}<sub>2</sub>MnÂ(Cp)Â(<i>t</i>-BuPH<sub>2</sub>) (<b>1</b>). This complex comprises a MnÂ(II) phosphide and is a dimer
in the solid state, containing a Mn<sub>2</sub>P<sub>2</sub> diamond
core. Consistent with the observation of a relatively short intermetal
distance of 2.8717(4) Ã… in <b>1</b>, DFT analysis of the
full structure points to a singlet ground state stabilized by a direct
Mn–Mn single bond. This is in line with the diamagnetic character
of <b>1</b> and an 18-electron count at Mn