Donor‐Acceptor Spiro‐Compounds — Syntheses, Structures, and Electronic Properties

Abstract

Abstract The six donor‐acceptor spiro compounds spiro[1,3‐dioxolane‐2,2′‐indan]‐1′,3′‐dione ( 8 ), spiro[indan‐2,2′‐[1,3]oxathiolane]‐1,3‐dione ( 9 ), spiro[1,3‐dithiolane‐2,2′‐indan]‐1′,3′‐dione ( 10 ), spiro[1,3‐benzodioxole‐2,2′‐indan]‐1′,3′‐dione ( 11 ), 5‐methylspiro[1,3‐benzodithiole‐2,2′‐indan]‐1′,3′‐dione ( 12 ), and spiro[indan‐2,2′‐naphtho[2,3‐ d ]‐1,3‐dioxole]‐1,3‐dione ( 13 ) have been prepared. Their He (I) photoelectron spectra and their UV/Vis spectra have been investigated. A comparison between the first PE bands of the spiro compounds and the corresponding fragments indicates only a very weak interaction between both parts. The UV/Vis spectra of 11‐13 show a moderate long‐wavelength shift of the first band as compared to 1,3‐indandione. This band is assigned to a transition from the HOMO(π), localized at the donor fragment, to the LUMO(π * ) of the acceptor moiety (charge transfer). X‐ray investigations of 8‐10 and 13 show no interaction between the two perpendicularly arranged moieties.