Synthesis and Characterization of Iron(II) Coordination Complexes with PPh2Py and DPEphos Ligands: A Combined Experimental and Theoretical Study

DOI: 10.22607/IJACS.2024.1203006

Research  Article

ABSTRACT

The synthesis and characterization of Iron(II) complexes [FeCl2(η2-P,N-PPh2Py)2] (1) and [FeCl2(η2-P,P-DPEphos)2] (2), with PPh2Py and DPEphos ligands, were performed using elemental analysis, ESI-mass, Fourier transform infrared spectra (FTIR), ultraviolet-visible, 1H and 31P{1H} nuclear magnetic resonance spectroscopy. FTIR measurements predicted cis-isomer to be the most stable form of complex 1 and trans-isomer to be the most stable form of complex 2. Quantum chemical calculations using first-principles density functional theory were performed on the two complexes at the B3LYP/LANL2DZ/6-31+G(d,p) level of theory. Theoretical calculations predicted that the ground state of the complexes would be a quintet spin state. However, in complex 1, the quintet spin state led to a significant elongation in Fe–P bond length to ~3.55 Å. Thus, a singlet (S = 1/2) spin state was considered for complex 1 which showed reasonable agreement with calculated geometric parameters. Trans configuration of complex 2 was shown to have a higher highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap (higher stability) than complex 1 which was attributed to the nature of the ligand coordinated to Fe(II) ion.
 

Key words: Fe(II) complexes, PPh2Py and DPEphos ligands, elemental analysis, Fourier Transform Infrared spectra, NMR spectroscopy, Density Functional Theory.

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Indian Journal of Advances in Chemical Science,

Volume: 12, Issue : 3,  August 2024

ISSN No.: 2320-0898 (Print); 2320-0928 (Electronic)