Synthesis and Characterization of (smif)2Mn (n = 0, M = V, Cr, Mn, Fe, Co, Ni, Ru; n = +1, M = Cr, Mn, Co, Rh, Ir; smif =1,3-di-(2-pyridyl)-2-azaallyl)

A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif)2M (1-M; M = Cr, Fe) were accomplished via treatment of M­(NSiMe3)2(THF)n (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2-azapropene); ortho-methylated (oMesmif)2Fe (2-Fe) and (oMe2smif)2Fe (3-Fe) were similarly prepared. Metatheses of MX2 variants with 2 equiv of Li­(smif) or Na­(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl3(THF)3 with 2 Li­(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na­(smif) and IrCl3(THF)3 in the presence of NaBPh4 gave [(smif)2Ir]­BPh4 (1+-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)2M]­OTf (1+-M), and treatment of Rh2(O2CCF3)4 with 4 equiv Na­(smif) and 2 AgOTf gave 1+-Rh. Characterizations by NMR, EPR, and UV–vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNCnb (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (ε ≈ 10 000–60 000 M–1cm–1), dominate the UV–visible spectra, and give crystals a metallic-looking appearance. High energy K-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(−))­(smif(2−))­Cr­(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr.本研究合成了一系列以三齿配体smif（即1,3-二(2-吡啶基)-2-氮杂烯丙基，1,3-di-(2-pyridyl)-2-azaallyl）为配体的维尔纳配合物（Werner complexes）。通过将M(NSiMe3)2(THF)n（M=Cr，n=2；M=Fe，n=1）与2当量的(smif)H（即1,3-二(2-吡啶基)-2-氮杂丙烯）反应，成功合成了(smif)2M（1-M；M=Cr、Fe）；类似地还制备了邻位甲基化产物(oMesmif)2Fe（2-Fe）与(oMe2smif)2Fe（3-Fe）。通过MX₂型前驱体与2当量的Li(smif)或Na(smif)发生复分解反应，可得到1-M（M=Cr、Mn、Fe、Co、Ni、Zn、Ru）。以Na/Hg为还原剂，将VCl₃(THF)₃与2当量Li(smif)进行复分解反应，得到1-V；而在四苯硼酸钠（NaBPh4）存在下，2当量Na(smif)与IrCl₃(THF)₃反应可生成[(smif)₂Ir]BPh₄（1+-Ir）。电化学实验中，利用三氟甲磺酸银（AgOTf）对1-M（M=Cr、Mn、Co）进行氧化，得到[(smif)₂M]OTf（1+-M）；将Rh₂(CF₃COO)₄与4当量Na(smif)及2当量AgOTf反应，同样得到1+-Rh。本研究通过核磁共振波谱（NMR, Nuclear Magnetic Resonance）、电子顺磁共振波谱（EPR, Electron Paramagnetic Resonance）、紫外-可见（UV–vis）光谱、超导量子干涉仪（SQUID）磁测量、X射线晶体学以及密度泛函理论（DFT, Density Functional Theory）计算对所有产物进行了表征。配体内（IL, intraligand）电荷跃迁源于电子从smif骨架独特的CNC非键（nonbonding）轨道跃迁至配体π*型轨道，该跃迁具有较高摩尔吸光系数（ε≈10 000~60 000 M⁻¹cm⁻¹），主导了体系的紫外-可见光谱，并使晶体呈现金属光泽外观。通过高能K边光谱表征证实，1-Cr中的smif配体为氧化还原活性配体（redox noninnocent ligand），其电子组态最优描述为(smif(−))(smif(2−))Cr(III)；1-Cr的X波段电子顺磁共振谱呈现出罕见的S=1信号。