Aqua-tri-fluorido-boron-1,3-dioxolan-2-one (1/2).

The crystal structure of the co-crystal of aqua-tri-fluorido-boron with two ethyl-ene carbonate (systematic name: 1,3-dioxolan-2-one) mol-ecules, BF 3 H 2 O·2OC(OCH 2 ) 2 , was determined by low-temperature single-crystal X-ray diffraction. The co-crystal crystallizes in the ortho-rhom-bic space group P 2 1 2 1 2 1 with four formula units per unit cell. The asymmetric unit consists of an aqua-tri-fluorido-boron mol-ecule and two ethyl-ene carbonate mol-ecules, connected by O-H⋯O=C hydrogen bonds. This crystal structure is an inter-esting example of a superacidic BF 3 H 2 O species co-crystallized with an organic carbonate.