A new polytype of orthoboric acid,H3BO3‐3T

The crystal structure of H₃BO₃‐3T, a new trigonal polytype of orthoboric acid, consists of sheets of hydrogen‐bonded B(OH)₃ mol­ecules similar to those found in the triclinic structure of orthoboric acid, H₃BO₃‐2A. In each case, van der Waals forces connect the sheets. However, the stacking sequences of the sheets differ between the two polymorphs. In H₃BO₃‐3T (space group P3₂), the sheets are stacked in the repeating sequence ABC…, whereas in H₃BO₃‐2A (space group ), the sheets are stacked in the repeating sequence AB….