(dme)MCl3(NNPh2) (dme = dimethoxyethane; M = Nb, Ta): a versatile synthon for [Ta=NNPh2] hydrazido(2-) complexes

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Inorganic Synthesis

Background:

• Hydrazido ligands are versatile building blocks in organometallic chemistry.
• Understanding the electronic properties of metal-ligand interactions is crucial for designing new materials.

Purpose of the Study:

• To synthesize and characterize novel tantalum and niobium complexes with a diphenylhydrazido ligand.
• To investigate the electronic structure and spectroscopic properties of the synthesized complexes.
• To explore the reactivity of these complexes with various ligands.

Main Methods:

• Synthesis via Lewis-acid assisted dehydrohalogenation of MCl(5) with diphenylhydrazine.
• Characterization using X-ray diffraction, IR, UV-vis, and NMR spectroscopy.
• Reactions with neutral, mono-, and dianionic ligands.

Main Results:

• Successful synthesis of monomeric (dme)TaCl(3)(NNPh(2)) (1) and (dme)NbCl(3)(NNPh(2)) (2).
• Complex 1 characterized, revealing a kappa(1)-bound hydrazido(2-) moiety.
• Complex 1 displays a dark blue color attributed to a lowered ligand-to-metal charge transfer (LMCT) transition.
• LMCT lowering is linked to an N(alpha)-N(beta) antibonding interaction that elevates the HOMO.
• Reactions with diverse ligands yield new complexes retaining the [Ta-NNPh(2)] moiety.

Conclusions:

• Novel tantalum and niobium hydrazido complexes were synthesized and characterized.
• The electronic structure of the hydrazido ligand significantly influences the complex's color and spectroscopic properties.
• The synthesized complexes demonstrate potential for further functionalization and application in coordination chemistry.