1 Analysis of the electronic delocalization in some B 12 ´s isoelectronic analogues doped with beryllium and/or carbon Rafael Islas, 1,2 Diego Inostroza, 3 David Arias-Olivares, 1,4 Bernardo Zúñiga-Gutiérrez, 2 Jordi Poater, 5,6 and Miquel Solà 7 1 Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Av. República 275, Santiago, Chile 2 Departamento de Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco, México. 3 Doctorado en Fisicoquímica molecular, Universidad Andres Bello, Av. República 275, Santiago, Chile 4 Center of Applied Nanoscience (CANS), Facultad de Ciencias Exactas, Universidad Andres Bello, Av. República 275, Santiago, Chile 5 Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, Martí i Franquès 1- 11, 08028 Barcelona, Catalonia, Spain 6 ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain 7 Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, C/ Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain Mail to: rafael.islas@unab.cl, bernardo.zuniga@academicos.udg.mx, miquel.sola@udg.edu Abstract In the current work, a new family of isoelectronic analogues to B12 is reported. The construction of this family was performed through the isoelectronic substitution principle to generate species such as B11C + , B11Be - , B10BeC, B10C2 2+ , B10Be2 2- B9Be2C - , and B9BeC2 + . The search for the global minimum was realized employing genetic algorithms, while the induced magnetic field, electronic localization function, magnetic current densities, and multicenter aromaticity criteria were calculated to understand their electronic delocalization. Our results show that, in general, C atoms avoid hypercoordination, whereas we have found species with Be atoms located in hypercoordinated positions that are relatively stable. Our analysis of aromaticity indicates that B12 has double  and  disk aromaticity. Mono, double or triple substitution of B by C + or Be - reduces somewhat the aromaticity of the clusters, but less in the case of Be - substitution. Keywords: B12; electronic delocalization; ELF; MCI; MICD; induced magnetic field; chemical transmutation; aromaticity; boron cluster.