Three-Coordinate, Cyclic Bent Allene Iron Complexes

Novel three-coordinate Fe complexes featuring 1,2-diphenyl-3,5-bis­(2,6-dimethylphenoxy)­pyrazolin-4-ylidine or “cyclic bent allene” (CBA) have been synthesized. Reaction with FeCl2(PPh3)2 results in the loss of both phosphines to yield monomeric Fe­(CBA)­Cl2. Treatment with 2 equiv of benzyl Grignard affords the three-coordinate alkylated product Fe­(CBA)­(Bn)2. Exposure of the alkylated species to an atmosphere of CO results in reductive elimination of 1,3-diphenylpropanone and formation of trigonal-bipyramidal Fe­(CBA)­(CO)4.本研究合成了以1,2-二苯基-3,5-双(2,6-二甲基苯氧基)吡唑啉-4-亚基（cyclic bent allene，CBA）为配体的新型三配位铁配合物。该配合物与FeCl₂(PPh₃)₂反应时，会失去两个膦配体，生成单核铁配合物Fe(CBA)Cl₂。使用2当量的苄基格氏试剂对其进行处理，可得到三配位烷基化产物Fe(CBA)(Bn)₂。将该烷基化产物暴露于一氧化碳气氛中，会发生还原消除反应，生成1,3-二苯基丙酮，并得到三角双锥构型的Fe(CBA)(CO)₄。