Neutral-ligand complexes of bis(imino)pyridine iron: Synthesis, structure, and spectroscopy
Neutral-ligand complexes of bis(imino)pyridine iron: Synthesis, structure, and spectroscopy
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DOI：
10.1021/ic700869h
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发表时间：
2007-08-20
影响因子：
4.6
通讯作者：
Chirik, Paul J.
中科院分区：
文献类型：
--
作者：
Bart, Suzanne C.;Lobkovsky, Emil;Chirik, Paul J.
由相应的双氮配合物((PDI)-P-IPR)Fe(N-2)(2)合成了一族双(亚氨基)吡啶铁中性配体衍生物((PDI)-P-IPR)FELN((PDI)-P-IPR=2，6-(2，6-Pr-I(2)-C6H3N=CME)(2)C6H3N)。当L是强场配体(如(BuNc)-Bu-t)或螯合烷基双膦(如Depe=1，2-双(二乙基膦)乙烷)时，得到一个五配位的抗磁化合物，没有顺磁态混合的光谱证据。将中性给体的电场强度降低到主要为sigma型配体，如(BuNH2)-Bu-t或THT(THT=四氢噻吩基)，也会产生抗磁性化合物。然而，面内双(亚氨基)吡啶氢的H-1核磁共振化学位移表现出很大的化学位移色散，表明S=1激发态通过自旋-轨道耦合混合而产生与温度无关的顺磁性(TIP)。X射线衍射的测量数据确定了每种结构类型的双(亚氨基)吡啶的络合还原，而穆斯堡尔参数和核磁共振光谱数据区分了铁的自旋态，并确定了顺磁激发态的贡献。
A family of bis(imino)pyridine iron neutral-ligand derivatives, ((PDI)-P-iPr)FeLn ((PDI)-P-iPr = 2,6-(2,6-Pr-i(2)-C6H3N=CMe)(2)C6H3N), has been synthesized from the corresponding bis(dinitrogen) complex, ((PDI)-P-iPr)Fe(N-2)(2). When L is a strong-field ligand such as (BuNC)-Bu-t or a chelating alkyl diphosphine such as DEPE (DEPE = 1,2-bis(diethylphosphino)ethane), a five-coordinate, diamagnetic compound results with no spectroscopic evidence for mixing of paramagnetic states. Reducing the field strength of the neutral donor to principally sigma-type ligands such as (BuNH2)-Bu-t or THT (THT = tetrahydrothiophene) also yielded diamagnetic compounds. However, the H-1 NMR chemical shifts of the in-plane bis(imino)pyridine hydrogens exhibit a large chemical shift dispersion indicative of temperature-independent paramagnetism (TIP) arising from mixing of an S = 1 excited state via spin-orbit coupling. Metrical data from X-ray diffraction establish bis(imino)pyridine chelate reduction for each structural type, while Mossbauer parameters and NMR spectroscopic data differentiate the spin states of the iron and identify contributions from paramagnetic excited states.