砷亚胺配位的高自旋亚铁配合物的合成、表征和乃春转移反应

Synthesis, Structure, and Nitrene-Transfer Reactivity of High-Spin Iron(Ⅱ) Complex Featuring Iminoarsorane Ligation

通过原位形成的胺基取代苯基锂与PhAsCl_2反应合成二胺基-胂配体,并进一步由二胺基-胂配体与[Fe(N(TMS)_2)_2]_2反应合成了(二胺基-胂)亚铁配合物[(κ-N,N,As-^(dfp)N_2As)Fe(THF)_2](3).通过配合物3与有机叠氮化物DippN_3反应实现了首例砷亚胺金属配合物[(κ-N,N,N-^(dfp)N_2AsN^(Dipp))Fe(THF)](4)的合成.配合物4可与2,6-二甲基苯基异腈以及三苯基膦发生乃春转移反应,生成配合物[(κ-N,N,As-^(dfp)N_2As)Fe(CNC_6H_3Me_2-2,6)_3](5)和[(κ-N,N,As-^(dfp)N_2As)Fe(PPh_3)](6)以及相应的有机物产物DippNCNC_6H_3Me_2-2,6和Ph_3PCNC_6H_3Me_2-2,6.这些配合物通过了各种谱学手段表征,其中配合物3～5的结构还通过单晶X射线衍射得到确认.

Treatment of （2,6-F2C6H3）（2-BrC6H4）NH with 2 equiv. of nBuLi, followed by the interaction with 0.5 equiv. of PhAsCl2 and quenching with aqueous solution, afforded the new bis（amido）-arsorane ligand （（o-（N-（2,6-2C6H3）NH）C6H4）2AsPh （denoted as H2（^dfpN2As））. The interaction of H2（^dfpN2As）） with 0.5 equiv. of[Fe（N（TMS）2）2]2 resulted in amine elimination and gave the bis（amido）-arsorene-iron（Ⅱ） complex[（κ-N,N,P-^dfpN2As）Fe（THF）2] （3）. Further treatment of 3 with the organic azide DippN3 rendered the formation of the first iminoarsorane-transition-metal complex[（κ-N,N,N-^dfpN2AsN^Dipp）Fe（THF）] （4） as an air- and moisture-sensitive green solid. Reactivity study indicated that 4 can undergo nitrene-transfer reactions with excess amounts of 2,6-dimethylphenylisocyanide and PPh3 to produce the nitrene-transfer products DippNCNC6H3Me2-2,6 and Ph3PCNC6H3Me2-2,6, respectively and the corresponding bis（amido）-arsorane-iron（Ⅱ） complexes[（κ-N,N,As-^dfpN2As）Fe（CNC6H3Me2-2,6）3] （5） and[（κ-N,N,As-^dfpN2As）Fe（PPh3）] （6）. These complexes were fully characterized by various spectroscopic methods. Solution magnetic susceptibility measurements and 57Fe M？ssbauer spectroscopy （δ=0.88 mm/s,｜ΔEQ｜=1.50 mm/s; δ=0.90 mm/s,｜ΔEQ｜=2.53 mm/s; and δ=0.65 mm/s,｜ΔEQ｜=2.23 mm/s for 3, 4, and 6, respectively） indicated that 3, 4 and 6 are high-spin iron（Ⅱ） complexes, whereas the well-resolved diamagnetic NMR spectra of 5 in combination with its 57Fe Mossbauer spectrum data （δ=0.05 mm/s,｜ΔEQ｜=0.40 mm/s） revealed its low-spin iron（Ⅱ） nature. The molecular structures of 3~5 have been characterized by single-crystal X-ray diffraction studies. The dianionic bis（amido）-arsorane ligands in 3 and 5 chelate to the metal centers in a fac-fashion with the Fe-As distances being 0.2562（3） and 0.2293（1） nm, respectively. The dianionic bis（amido）-iminoarsorane ligand in 4 binds to the iron（Ⅱ） center in a fac-fashion. The Fe-As distance （0.285 nm） observed in 4 is longer than the sum of the covalent radii of Fe and As, indicating the absence of strong Fe-As interaction in the iminoarsorane-iron（Ⅱ） complex. Its As-N distance of 0.1752（3） nm is found comparable to those of the As-N bonds in the reported iminoarsoranes and bis（arsoranylidene） ammonium compounds.