Matrix isolation studies of transition metal halides and main group Lewis acid‒base complexes

Sakr, Ahmed Khairy Ali Mohammed

Abstract

The main purpose of this work was to synthesise and study the binary fluorides of nickel, cobalt and chromium, and the binary halides of palladium and molybdenum in solid argon matrices. Both UV/vis spectroscopy and FTIR spectroscopy were employed to identify the products formed. Additionally, this work also investigated the reaction between SiF4 with alkyl phosphines.
In the beginning, the work focused on isolation of atomic nickel, cobalt, molybdenum, and palladium in neat argon matrices. The FTIR data revealed the interaction of nickel and fluorine atoms in solid argon matrix and the formation of nickel fluoride molecules NiF, NiF2, and NiF4 and also provided evidence for the formation of NiF3 molecules. Moreover, cobalt atoms trapped in a matrix of argon doped with fluorine yielded the formation of CoF, CoF2, CoF3, CoF4, and Co2F2 molecules. Furthermore, molybdenum fluoride species in an argon matrix have been obtained, which is the first observation of the vibrational modes for MoF and MoF2 in matrices. The geometry of MoF2 species was assigned to be bent with a bond angle of 132°. In addition, FTIR data indicated the formation of matrix isolated chromium fluorides in solid argon matrix. The study succeeded in the characterisation of CrF and CrF6 molecules, as well as the previously identified CrF2, CrF3, CrF4 and CrF5. The IR band related to CrF6 is observed at 757 cm−1. A computational study suggested that PdCl2 is linear.
The reaction between SiF4 and PMe3 at cryogenic temperatures led to the formation of a SiF4−PMe3 complex and indicated the formation of two different species. The reaction between SiF4 and PEt3 revealed the formation of a 1:1 adduct of trigonal bipyramid structure with axial PEt3 of SiF4.PEt3 and a 1:2 complex of trans–[SiF4.(PEt3)2] structure. The results were supported by computational data.

Citation

Sakr, A. K. A. M. Matrix isolation studies of transition metal halides and main group Lewis acid‒base complexes. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4224599

• Thesis Type: Thesis
• Deposit Date: Jan 10, 2023
• Publicly Available Date: Feb 24, 2023
• Keywords: Chemistry
• Public URL: https://hull-repository.worktribe.com/output/4224599
• Additional Information: Department of Chemistry, The University of Hull
• Award Date: Sep 1, 2018