Bond lengths (Å) of BBCT, BBCT-Me, and [3]phenylene determined by X-ray single-crystal analysis.

Compounda	i	ii	iii	iv	v	vi	vii	viii
BBCT	1.341(4)	1.443(3)	1.342(4)	1.505(3)	1.496(3)	1.384(3)	1.425(3)	1.387(3)
BBCT-Me	1.349(2)	1.443(2)	1.353(2)	1.502(2)	1.501(2)	1.393(2)	1.430(2)	1.389(2)
[3]Phenyleneb	1.363(2)	1.419(2)	1.365(2)	1.514(2)	1.514(2)	1.392(2)	1.416(2)	1.390(2)

^aBond positions are described in Fig. 1.

^bBond lengths of [3]phenylene were referred from ref. 55.