Synthesis and Characterization of Tungsten Alkylidene and Alkylidyne Complexes Featuring a New Carbazole-Based Rigid Trianionic ONO3- Pincer-Type Ligand

摘要

The design and synthesis of a rigid carbazole trianionic pincer ligand and its tungsten alkylidene [CBZ-ONO]W=(CHBu)-Bu-t((OBu)-Bu-t) (3) and anionic alkylidyne {Ph3PCH3}{[CBZ-ONO]W (CBu)-Bu-t((OBu)-Bu-t)} (4) complexes are reported. Designed to maximize the inorganic enamine effect by constraining the N atom lone pair, the carbazole ligand achieves high planarity. However, the orbital overlap remains similar to that of the flexible ligand [CF3-ONO]H-3 (1). The neutral alkylidyne complex could not be synthesized. The complexes were characterized by multinuclear NMR spectroscopy, combustion analysis, mass spectrometry, and single-crystal X-ray diffraction. DFT calculations reveal an inorganic enamine orbital overlap within the alkylidyne complexes bearing both the rigid and flexible ligands.