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

The title compound, C(20)H(22)BNO(2), 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 C(2)H(2) = 0.0333 Å) with the ethenyl-C(NC(2)-pyrrole) plane (r.m.s. deviation CNC(2) 0.0423 Å) and the ethenyl-C(BO(2)-1,3,2-dioxaborolane) plane (r.m.s. deviation BCO(2) 0.0082 Å) 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. [Image: see text]