A new polymorph of tetraphenyldiboroxane

A new polymorph of tetraphenyldiboroxane [or oxybis(diphenylborane)], C24H20B2O, (Ia), has been found. It is monoclinic, like the already known form, (Ib), and can be re ned in the same space group, namely P2(1)/ c, or in the equivalent setting P2(1)/ n. The molecular conformations of the two polymorphs differ in the rotations of two of the phenyl rings about the B - C bonds, leading to markedly different packing patterns and cell dimensions.