9-[(Z)-2-(4,4,5,5-Tetra­methyl-1,3,2-dioxaborolan-2-yl)ethen­yl]-9H-carbazole

The title compound, C20H22BNO2, has a polarized π-system due to resonance between N—C(H)=C(H)—B and ionic N+=C(H)—C(H)=B− canonical structures. The dihedral angles between the ethenyl plane (r.m.s. deviation for C2H2 = 0.0333 A) with the ethenyl-C(NC2-pyrrole) plane (r.m.s. deviation CNC2 0.0423 A) and the ethenyl-C(BO2-1,3,2-dioxaborolane) plane (r.m.s. deviation BCO2 0.0082 A) are 45.86 (8) and 37.47 (8)°, respectively, and are greater than those found for the previously reported E-isomer [Hatayama & Okuno (2012) Acta Cryst. E68, o84]. In comparison with the E-isomer, the reduced planarity of Z-isomer results in a decrease of the contribution of the N+=C(H)—C(H)=B− canonical structure.