Endohedral Ca@B₃₈: stabilization of a B₃₈²⁻ borospherene dianion by metal encapsulation

Based on extensive global-minimum searches and first-principles electronic structure calculations, we present the viability of an endohedral metalloborospherene C_s Ca@B₃₈ (1) which contains a C_s B₃₈²⁻ (2) dianion composed of interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the B_n^q (q = n − 40) borospherene family from n = 39–42 to n = 38. Transition metal endohedral complexes C_s M@B₃₈ (M = Sc, Y, Ti) (3, 5, 7) based on C_s B₃₈²⁻ (2) are also predicted.