A rare terminal dinitrogen complex of chromium

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Coordination Chemistry

Background:

• Dinitrogen (N2) is a crucial but inert molecule.
• Transition metal complexes are key to N2 activation.
• Understanding metal-N2 bonding is vital for catalysis.

Purpose of the Study:

• To synthesize and characterize cis and trans-chromium-dinitrogen complexes.
• To investigate the influence of pendant amines on complex geometry.
• To elucidate the electronic factors governing chromium-N2 binding.

Main Methods:

• Synthesis of novel diphosphine-supported chromium complexes.
• Characterization using spectroscopic and crystallographic techniques.
• Computational electronic structure calculations (e.g., DFT).

Main Results:

• Successful preparation of cis and trans-Cr-N2 complexes with P(Ph)2N(Bn)2 ligand.
• Demonstration that pendant amines in the second coordination sphere control isomer preference.
• Electronic structure calculations reveal minimal Cr-N2 back-bonding.

Conclusions:

• The electronic polarization of the N2 ligand, not back-bonding, stabilizes Cr-N2 interactions.
• Second-sphere coordination effects are critical in dictating geometric isomerism in metal-dinitrogen complexes.