Bond lengths and angles in the X-ray structure of carbene 4e.

Bond	Bond length, Å	Bond order	Angle	Angle value, °
C1–N2	1.346(3)	1.736	N1C1N2	100.14(17)
C1–N1	1.390(3)	1.483	N1C2N3	109.82(17)
C2–N3	1.313(2)	1.925	N1C1N2N3	−0.7(2)
C3–N4	1.383(3)	1.523	N2N3C2N1	1.0(2)
N1–N2	1.393(2)	1.287	N2N3C2C13	−178.05(19)
N2–C9	1.494(3)	0.885	N1C2C13C14	33.6(3)
C2–C13	1.476(3)	1.294	C2N1C3C4	76.9(3)
C3–N1	1.436(3)	1.218	—	—