[5-Hydroxy-3-phenyl-1-(pyridin-2-yl)pyrazol-5-olato]diphenylboron

In the title compound, C26H20BN3O, the B atom has tetrahedral geometry and is linked to two phenyl rings, the O atom of the hydroxypyrazole ring and the N atom of the pyridinyl ring. A six-membered BOCNCN ring forms by coordination of the B atom and the pyridinyl N atom. The BOCNCN ring has an envelope conformation [dihedral angle = 36.7 (1)° between the planar ring atoms and the flap] with the B atom out of the plane. In the 1-(2-pyridinyl)-3-phenyl-5-hydroxypyrazole group, the pyridinyl ring, the phenyl ring and the pyrazole ring are almost coplanar: the pyrazole ring makes a dihedral angle of 9.56 (8)° with the pyridinyl ring and 17.68 (7)° with the phenyl ring. The crystal structure is stabilized by π–π stacking interactions involving the pyridinyl and pyrazole rings of centrosymmetrically related molecules, with ring centroid separations of 3.54 (5) .