Crystal structure of boron difluoride acetylnaphtholates

The crystal structure of luminescent isomeric boron difluoride acetylnaphtholates: 2-acetyl-1-naphthoboron difluoride (1) and 1-acetyl-2-naphthoboron difluoride (2) has been studied. Molecules of 1 make infinite stacks of coplanar molecules in crystals, and molecules of 2 are arranged in the crystalline cell in the form of isolated π-dimers. Unlike a planar molecule of 1, the methyl group in α-position of the diketonate ring drops out of the molecule plane in a molecule of 2, thus forcing the chelate ring to bend considerably along the line C(11)-B. The structure features of 1 cause a bathochromic shift of the luminescence band in comparison with 2.