Our research interests bridge the traditional disciplines of organic and inorganic chemistry.  Transition metal-mediated organic synthesis and homogeneous catalysis constitute the principal themes of our research program.  More specifically, we are developing the synthesis and reactivity of early and late transition metal complexes that are of interest for applications in organic synthesis, polymer chemistry, modeling of catalytic reactions, and as catalyst precursors.  We are also developing environmentally benign chemical processes.  Current projects include:

The design of well-defined titanium(II) reductants.

The main goal of this research is the development of well-characterized Ti(II) reductants that operate via well-understood mechanisms.  Better understanding of the synthesis, structure, and reactivity of low-valent titanium complexes is required in order to achieve better mechanistic understanding and greater control over regio-, diastereo-, and chemo-selectivity in titanium-mediated carbon-carbon bond forming reactions.  As an approach to achieving this goal, we are probing ancillary ligand effects in titanium chemistry.  Emphasis is placed on discovery and use of supporting ligands that afford well-characterized Ti(II) complexes or synthetic equivalents.   We are interrogating the reactivity of these well-defined compounds with particular emphasis on their reactions with unsaturated organic substrates, such as alkynes, alkenes, imines, aldehydes, and ketones.  Our mechanistic investigations are helping to elucidate parameters key to designing selective titanium reductants.

The design of catalysts for ethylene trimerization and olefin polymerization.

Selective trimerization of ethylene to yield 1-hexene is an important objective in the petrochemical industry due to growing application of 1-hexene as co-monomer in catalytic olefin polymerization for production of polyethylene.  Most of the systems known to catalyze ethylene trimerization are based on homogeneous Cr compounds. Recently, catalysts based on Ti and Ta have been reported.  We are developing early- and late transition metal complexes for selective catalysis of ethylene trimerization into 1-hexene, and for polymerization of ethylene and alpha-olefins.

 This work is supported by the National Science Foundation (NSF Grant # CHE-0416098).

Aqueous Organometallic Chemistry.

The development of non-toxic and enviromentally-benign commercial chemical processes is an important objective.  There is considerable interest in aqueous organometallic chemistry of the transition metals because water-soluble transition metal compounds have found applications: (i) as catalysts in commercially-viable industrial processes for bulk and fine chemical synthesis, and (ii) in biomedicine.  Currently, we are exploring the synthesis, kinetic stability in water, and aqueous organometallic chemistry of water-soluble and air-stable complexes of  rhodium and iridium.

The synthesis of tailored group 9 metal electrophiles.

The synthesis and chemistry of electrophilic group 9 metal complexes remain inadequately studied, due primarily to the anticipated substitution inertness of low spin d6 metal ions in coordinatively saturated environments.  However, there is growing evidence that this inertness may be overcome through use of weakly coordinating ligand(s) and noncoordinating counterions to stabilize the metal center, and thereby avoid deactivation of the electrophilic metal species.  We are developing well-characterized electrophilic Co(III), Rh(III), and Ir(III) complexes that contain a labile ligand and a noncoordinating counterion.  The complexes have the potential to catalyze hydration of olefins.

Postdoctoral Fellowships Opportunities (for U.S. nationals only)
If you are interested in working with our research group and qualify for one of these programs, I will gladly sponsor your application. Good luck! 

• Ozerov, O. V.; Patrick, B. O.; Ladipo, F. T. "Highly Regioselective [2 + 2 + 2] Cycloaddition of Terminal Alkynes Catalyzed by eta 6-Arene Complexes of Titanium Supported by Dimethylsilyl-Bridged p-tert-Butyl Calix[4]arene Ligand", J. Am. Chem. Soc. 2000, 122, 6423.
• Ozerov, O. V.; Parkin, S.; Brock, C. P.; Ladipo, F. T. "Reactivity of a Well-Characterized Titananorbornadiene(eta 6-arene) Complex with Ketones and Aldehydes", Organometallics 2000, 19, 4187.
• Ozerov, O. V.; Brock, C. P.; Carr, S.; Parkin, S.; Ladipo, F. T. "Unusual Reductive Coupling of Alkynes and Ketones: Reactivity of Titanacycles Supported by Dimethylsilylcalix[4]arene (DMSC) Ligand", Organometallics 2000, 19, 5016.
• Kingston, J. V.; Ozerov, O. V.; Parkin, S. Brock, C. P.; Ladipo, F. T. " Mechanistic Insight into Fragmentation Reactions of Titanapinacolate Complexes" J. Am. Chem. Soc. 2002, 124, 12217.
• Kingston, J. V.; Sarveswaran, V.; Parkin, S.; Ladipo, F. T. "Synthesis and Reactivity of [(DMSC)Ti(eta 2-OCAr₂)L₂] Complexes (DMSC = Dimethylsilyl-Bridged p-tert-Butylcalix[4]arene Dianion, Ar = Aryl Group, and L₂ = Delocalized Diimine)" Organometallics 2003, 22, 136.
• Owiny, D.; Parkin, S.; Ladipo, F. T. "Synthesis, Structural Determination, and Ethylene Polymerization Chemistry of Mono(salicylaldiminato) Complexes of Titanium(IV)" J. Organomet. Chem. 2003, 678, 134.
• Ladipo, F. T.; Sarveswaran, V.; Kingston, J. V.; Huyck, R. A.; Bylikin, S. Y.; Carr, S. D.; Watts, R.; Parkin, S."Synthesis, Characterization, And Alkyne Cyclotrimerization Chemistry of Titanium Complexes Supported by Calixarene-Derived Bis(Aryloxide) Ligation." J. Organomet. Chem. 2004, 689, 502.
• Owiny, D.; Kingston, J. V.; Maynor, M.; Parkin, S.;Kampf, J. W.; Ladipo, F. T."Reductive Coupling of [(RO)₂Ti(L₂)₂] Complexes Containing a Chelating Bis(aryloxide) Ligand with Ketones (L₂ = bpy, dmbpy, or phen)." Organometallics 2005, 24, 3995.