CsAlB 3 O 6 Cl: the rational construction of a KBBF-type structure with aligned 2 ∞ [AlB 3 O 6 Cl] layers via introducing unprecedented [AlO 3 Cl] tetrahedra.

The first chloroaluminoborate, CsAlB 3 O 6 Cl, with innovative AlO 3 Cl tetrahedra and a perfect planar arrangement of [B 3 O 6 ] groups, was structurally designed and synthesized via chlorination of [AlO 4 ] tetrahedra. Simultaneously, the smooth introduction of the [AlO 3 Cl] group into borates initiates the development of a chloroaluminoborate and greatly enriches the structural chemistry of aluminoborates.