UV-Visible and MCD Spectroscopy

In a few instances the technique of magnetic circular dichroism (MCD) spectroscopy has been used to corroborate assignments based on UV-visible spectroscopy. For example, the assignment of the intense 360 nm band for [S,N,Y to a r (2e ) r (2a2 ) (HOMO LUMO) excitation has been confirmed by the measurement of the MCD spectrum of The MCD spectrum of [S4N3] indicates that each of the 

The similarity in the electronic structures of the eight r-electron systems R2PN3S2 (3.25) and [S3N3O2] (3.26) is also reflected in their UV-visible spectra. Both these heterocycles have an intense purple colour due to a visible band at ca. 560 nm attributed to the HOMO (tt ) 

LUMO (tc ) transition. The 1,3- and 1,5- isomers of the eight-membered R2P(NSN)2PR2 (R = Me, Ph) rings, 3.27 and 3.28, respectively, exhibit characteristically different colours. The 1,3-isomer 3.27 is dark orange with an absorption maximum at ca. 460 nm, whereas the 1,5 isomer has a very pale yellow colour. In the absence of a 

Some acyclic sulfur-nitrogen compounds also exhibit intense colours. For example, S-nitrosothiols RSNO are either green, red or pink (Section 9.7). Their UV-visible spectra show an intense band in the 330-350 nm region (no it ) and a weaker band in the visible region at 550-600 nm 

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