 Beryllium forms binary compounds with many non @-@ metals . Anhydrous halides are known for F , Cl , Br and I. BeF2 has a silica @-@ like structure with corner @-@ shared <unk> tetrahedra . BeCl2 and <unk> have chain structures with edge @-@ shared tetrahedra . All beryllium halides have a linear monomeric molecular structure in the gas phase . 
