Professor Joseph West

Project Title: 
Prediction of Air Stability for Primary Phosphines; Formation Thermodynamics and Kinetics of Cyclodiphosphazanes and Cyclodisilazanes; Hydrolysis of Bis(cyclopentadienyl)titanium(IV) Complexes

These researchers are using MSI for three projects:

  • Prediction of Air Stability for Primary Phosphines: Primary phosphines (RPH2) are of interest, despite their notorious reactivity with oxygen in the open air, as sterically unencumbered phosphine ligands for transition metals as well as analogues to primary amines (RNH2). Surprisingly, a few examples of air-stable primary phosphines have been reported with oddly varying structural types. A straightforward DFT method has been reported for predicting the air stability of these species though the reported data set is limited in depth and requires, in some cases, long calculation times. This group is exploring much faster calculation methods (HF with small basis sets and semi-empirical) to provide the same predictive result. They are benchmarking their results on a much wider and deeper dataset than was previously published using the reported method as well as their simpler approaches. Additionally, they are attempting to uncover possible correlations with standard output data for the phosphines themselves (not their ionized and/or radical forms) to further expedite identification of possible air-stable species.
  • Formation Thermodynamics and Kinetics of Cyclodiphosphazanes and Cyclodisilazanes: Four-membered ring systems of P, N, and Si present numerous electronic and structural possibilities through one simple structural motif. Cyclodiphosphazanes and the rarer cyclodisilazanes all contain the same four-membered ring with alternating elements and the all-important exo-amines in either a cis or trans conformation. While generally useful as transition metal ligands, that usefulness is muted by the lack of predictability in product isolation and the penchant for isomerization (cis to trans) that has been observed. Modeling the formation (kinetics and thermodynamics) and isomerization of these compounds via electronic structure calculations can provide insight into the underlying forces at work to aid in their design and achieve a greater outcome when they are implemented. These researchers use GAMESS software suite to carry out these calculations using DFT methods for structure optimizations and coupled cluster methods for subsequent energy calculations.
  • Hydrolysis of Bis(cyclopentadienyl)titanium(IV) complexes: Dichloridobis(cyclopentadienyl)titanium(IV), a.k.a. titanocene dichloride, was the first metallocene, organometallic, and non-Pt-containing complex to undergo human trials as a cancer drug. At least in part, the hydrolysis of this complex is an important characteristic to its suggested modes of action. This group is investigating its hydrolysis pathways with biological role-players in consideration and explicit solvent effects that have not been previously accounted for. Additionally, they are applying these approaches to numerous analogues of titanocene dichloride with replacement anionic (both mono- and bidentate) ligands in lieu of the chlorides. It is hoped that by selecting for an appropriate hydrolysis favorability and rate a more active drug target can be identified. This computational research is in direct support of recently initiated experimental work to test these same properties in the lab setting.

Project Investigators

Jessica Bartz
Taylor Bell
Sylvia Chase
Mackenzie Velarde
Isaac Viss
Sebastian Welp
Professor Joseph West
 
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