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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Spin Propensities of Octahedral Complexes From Density Functional Theory
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Spin Propensities of Octahedral Complexes From Density Functional Theory

机译：从密度泛函理论看八面体配合物的自旋倾向

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The fundamental balance between high- and low-spin states of transition metal systems depends-on both the metal ion and the ligands surrounding it as often visualized by the spectrochemical series. Most density functionals do riot reproduce this balance, and teal spin state propensities depend on orbital pairing and vibrational entropies absent in the spectrochemical series. Thus, :we systematically computed the tendency toward high or low spin of "text-book" octahedral metal complexes versus ligand and metal type, using eight density functionals. Dispersion effects were generally <5 kJ/mol, favoring low-spin states. Zero-point energies favored high-spin states up to 33 kJ/mol for strong ligands, but down to a few kilojoules per mole for weak ligands. Vibrational entropy also favored high-Tin states up to 40 kJ/mol, most for strong ligands. Jahn-Teller distortion in Co(II) low-spin states, particularly stable d(6) low-spin states, and entropy corrections were consistent with experiment. Entropy and zero-point energy corrections were Markedly lower for Co(II) and Mn(III), viz., the differential ligand field stabilization energy, and can only be ignored for-weak ligands. The data enable simple assessment of Spin state propensities versus ligand and metal type and reveal, e.g., that CN- is consistently weaker than CO for M(II) but stronger than CO for M(III) and SCN- and NCS- change order in M(II) versus M(III) complexes. Contrary-to expectation based on the spectrochemical series, Cl- and Br- are very Close in spin state propensity because the pairing penalty for low spin is smaller in Br-. Thus, for the M(II) complexes, we find a consensus order of Br- similar to Cl- < H2O < SCN- < NCS- similar to NH3 < CN- < CO, whereas for the M(III) complexes, an approximate order is Br- similar to Cl- < H2O similar to NCS- similar to SCN- < NH3 < CO < CN-.
机译：过渡金属系统的高和低自旋态之间的基本平衡取决于光谱化学系列经常看到的金属离子和周围的配体。多数密度泛函的确能重现这种平衡，并且蓝​​绿色的自旋态倾向取决于光谱化学序列中不存在的轨道对和振动熵。因此，我们使用八种密度泛函系统地计算了“教科书”八面体金属配合物相对于配体和金属类型的高或低自旋趋势。分散效应通常<5 kJ / mol，有利于低旋转态。零点能量有利于强配体高达33 kJ / mol的高自旋态，但对于弱配体则低至每摩尔几千焦耳。振动熵也有利于高达40 kJ / mol的高锡态，大多数用于强配体。 Co（II）低自旋态（尤其是稳定的d（6）低自旋态）中的Jahn-Teller畸变和熵校正与实验一致。 Co（II）和Mn（III）的熵和零点能量校正显着降低，即微分配体场稳定能，对于弱配体只能忽略不计。数据可以简单地评估自旋态倾向与配体和金属类型的关系，并揭示，例如，对于M（II），CN-始终比CO弱，但对于M（III）和SCN-和NCS-变化顺序，CN-始终比CO强。 M（II）与M（III）配合物。与基于光谱化学序列的预期相反，Cl-和Br-在自旋态倾向非常接近，因为低自旋的配对罚分在Br-中较小。因此，对于M（II）配合物，我们发现Br-与Cl-

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