Halocarbonyltungsten(II) Complexes Containing Tripodal Tris(pyrazolyl)borate Ligands.

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Inorganic Synthesis

Background:

• Tricarbonyl tungsten complexes with hydrotris(pyrazolyl)borate ligands are versatile synthetic intermediates.
• Understanding ligand and metal reactivity is crucial for developing new organometallic compounds.

Purpose of the Study:

• To synthesize and characterize novel halo tricarbonyl tungsten complexes.
• To investigate the reactivity of these complexes under decarbonylation conditions.
• To explore the structural features of the resulting dicarbonyl and acetonitrile complexes.

Main Methods:

• Synthesis of halo tricarbonyl tungsten complexes via reaction of precursor complexes with halogenating agents.
• Spectroscopic characterization (IR, NMR) of the synthesized complexes.
• X-ray crystallography to determine the structures of key intermediates and products.
• Thermal decarbonylation studies in various solvents.

Main Results:

• Successful synthesis of LWX(CO)(3) (X = I, Br, Cl) and L(Pr)WI(CO)(3) complexes.
• Observation of competitive bromination on both tungsten and the hydrotris(pyrazolyl)borate ligand.
• Characterization of fluxional carbonyl-capped octahedral structures for tricarbonyl complexes.
• Conversion of tricarbonyl complexes to paramagnetic dicarbonyl species LWX(CO)(2) and L(Br)WBr(CO)(2).
• Formation of a novel seven-coordinate complex L(Br)WBr(MeCN-kappa(2)N,C)(CO) featuring a side-on acetonitrile ligand.

Conclusions:

• The study demonstrates a facile route to tungsten halo tricarbonyl complexes.
• Decarbonylation provides access to paramagnetic dicarbonyl tungsten species with unique structural motifs.
• The formation of the acetonitrile complex highlights the potential for further functionalization and reactivity studies.