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Isomeric mono- and bis[(phosphane)gold(I)] thiocyanate complexes
Raphael J F Berger1, Michael Patzschke, Daniel Schneider
1Department of Chemistry, University of Helsinki, Finland.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|April 2, 2005
Summary
This study uses quantum chemical calculations to identify two isomers of trimethylphosphine gold(I) thiocyanate (Me(3)PAuSCN) and their corresponding IR spectra. It also investigates the formation of dinuclear gold complexes, revealing multiple cationic isomers.
Area of Science:
- Organometallic Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- The vibrational spectra of organometallic compounds provide crucial insights into their structure and bonding.
- Distinguishing between isomers in solid-state and solution phases is essential for understanding reaction mechanisms.
Purpose of the Study:
- To assign infrared (IR) spectral signals of trimethylphosphine gold(I) thiocyanate (Me(3)PAuSCN) to specific isomeric forms.
- To investigate the formation and structural characterization of dinuclear gold complexes derived from Me(3)PAuSCN.
- To compare experimental spectroscopic data with theoretical quantum chemical calculations.
Main Methods:
- Solid-state Infrared (IR) spectroscopy was used to analyze vibrational frequencies.
- Quantum chemical ab initio calculations (MP2 level of theory) were employed to determine molecular structures, vibrational frequencies, and relative energies.
- Reaction of Me(3)PAuSCN with [(Me(3)P)Au](+)[SbF(6)](-) under controlled conditions to synthesize dinuclear products.
Main Results:
- Two signals in the C-N stretching region of the IR spectrum of Me(3)PAuSCN were assigned to the Me(3)PAuNCS and Me(3)PAuSCN isomers.
- Ab initio calculations accurately predicted the vibrational frequencies and relative energies of these isomers, matching experimental IR data.
- The reaction yielded a dinuclear gold complex, with ab initio calculations and IR data suggesting the presence of at least three cationic isomers, with two being predominant.
Conclusions:
- Quantum chemical calculations are a reliable tool for assigning isomeric forms of organometallic thiocyanates based on IR spectroscopy.
- The study elucidates the structural complexity of dinuclear gold complexes formed from Me(3)PAuSCN, highlighting the presence of multiple isomers.
- A comprehensive understanding of the interplay between theoretical predictions and experimental spectroscopic evidence is demonstrated.