Dicarbenes spin ground states

Topological Control of the High-Spin vs. Low-Spin Ground States of n-Conjugated Diradicals and Dicarbenes... 

Encouraged by the experimental finding (Itoh, 1967 Wasserman et al., 1967) that the dicarbene [15 m = 2] ( = [3]) had a ground quintet state, i.e. all four spins were ferromagnetically coupled, Iwamura and Itoh have been engaged in a project directed towards the construction of the higher series of poly(carbenes) [15], [23] and [24] (Iwamura et al., 1985 Teki et al., 1983, 1985, 1986). 

The chemistry of high-spin polycarbenes started in 1967 when two groups led by K. Itoh [1] and E. Wasserman [2] reported independently their findings that OT-phenylene-dicarbene Ic generated by the photolysis of diazo compound Id has a ground quintet state. Prior to this report, A. M. Trozzolo and coworkers... 

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