関連する実験動画
Updated: Jul 10, 2026

10:37
Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
自由のシリリウムイオンの結晶学的証拠
Kee-Chan Kim1, Christopher A Reed, Douglas W Elliott
1Department of Chemistry, University of California, Riverside, CA 92521-0403, USA.
まとめ
この研究は,カルボランアニオンによって安定した3座標のシリルカチオン, [(Mes) 3Si] + の証拠を提供します. 巨大なメシチル群は,シリコンの中心を保護し,その分離と特徴づけを可能にします.
科学分野:
- オーガノシリコン化学 化学
- カーボラン化学
- 構造化学についてです.
背景:
- 三座標のシリコン種は,典型的には高度反応性の中間物質である.
- シリルカチオンの安定化は,シリコン結合と反応性を理解するために重要である.
- 以前の研究では,一時的なシリルカチオンや,体積が小さい置換物を持つものに焦点を当てていた.
研究 の 目的:
- 安定した3座標のシリルカチオンを合成し,特徴づけること.
- ステリカルに阻害されたシリケーションの構造および電子特性を調査する.
- 異なるフェーズにおける三重調整の維持を確認する.
主な方法:
- [(Mes) 3Si][H-CB11Me5Br6].C6H6.6の単結晶X線 difrakションについて
- 固体29Si核磁気共振 (NMR) スペクトロスコーピー. 固体29Si核磁気共振 (NMR) スペクトロスコーピー. 固体29Si核磁気共振 (NMR) スペクトロスコーピー. 固体29Si核磁気共振 (NMR) スペクトロスコーピー. 固体29Si核磁気共振 (NMR) スペクトロスコーピー.
- 溶液状態のNMRとガス相計算研究との比較.
主要な成果:
- 結晶構造は,離散的で平面的な3座標のシリルカチオン, [(Mes) 3Si]+ を明らかにしています.
- メシチル (Mes) 置換剤の巨大なオーソメチル群は,シリコンの中心を効果的に遮断する.
- 固体 29Si NMR 化学シフト (226.7 ppm) は溶液とガス相値と密接に一致し,安定性を確認しています.
- カーボランアニオンとベンゼン溶酸塩分子は,シリルカチオンから十分に分離されています.
結論:
- 安定した3座標のシリルカチオンを分離し,特徴づけることができます.
- 巨大なアリル基によるステリック保護は,これらの珍しいシリコン種を安定させるための鍵です.
- 三座標のシリコンセンターは,固体,溶液,ガス相において無傷のままである.
関連する概念動画
Trends in Lattice Energy: Ion Size and Charge
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Lattice Energies of Ionic Crystals
Lattice energy represents the energy released when gaseous cations and anions combine to form an ionic solid, reflecting the strength of electrostatic interactions within the crystal. This process is fundamentally governed by Coulombic attraction between oppositely charged ions, where the potential energy varies inversely with the interionic distance and directly with the product of ionic charges. As ions approach one another, the electrostatic energy becomes increasingly negative, indicating a...
Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...

