In this work, ab initio calculations are performed to characterize cooperative effects between tetrel bond interactions in linear (CH3CN)(2-7) and (CH3NC)(2-7) clusters. It is found that increasing the size of the clusters brings about an important reduction in the tetrel bond distances, with the effect being most significant in the central units. To shed more light on the cooperative phenomenon, molecular electrostatic potential and electron density analyses are performed. According to interaction energy decomposition analysis, cooperative effects enhance the covalency of C center dot center dot center dot N and C center dot center dot center dot C interactions. (C) 2015 Elsevier B.V. All rights reserved.