Table 1. Calculated (B3LYP-D3/def2-TZVPecp) C=C Bond Distances (Å) and C–X–C Bond Angles (Degrees, in Parentheses) for Compounds 1^El.

group 13	group 14	group 15	group 16
B 1.346 (54.6)	C 1.287 (50.6)	N 1.269 (49.5)	O 1.269 (48.0)
Al 1.369 (43.3)	Si 1.330 (43.1)	P 1.292 (41.1)	S 1.271 (40.1)
Ga 1.356 (41.8)	Ge 1.319 (40.1)	As 1.287 (37.8)	Se 1.268 (36.8)
In 1.330 (36.1)	Sn 1.320 (36.3)	Sb 1.287 (34.3)	Te 1.267 (33.4)
Tl 1.201 (22.2)	Pb 1.203 (23.7)	Bi 1.280 (32.4)	Po 1.261 (31.5)