The aromatic, bonding, and structural characteristics of the Si4C2H2-C2B4H6, Si2C4H4_C4B2H6, and other SinC2H2-C2BnHn+2 (n = 1, 2, 3, 5) isovalent pairs are studied using density functional theory (DFT) and coupled cluster methods to fully illustrate the homology of the two species. This homology, which is based on the replacement of the carborane B-H units by isovalent Si atoms, is extended to all three characteristics (structural, electronic, and aromatic) and includes all three lowest-energy structures of the isovalent pairs. This type of "boron connection", which has been tested for silicon clusters recently, seems to be a valid and extremely useful concept. For the aromatic properties of the SinC2H2-C2BnHn+2 Species, expressed through the nucleus independent chemical shifts (NICS), a strange odd-even effect with respect to the number of Si atoms is observed which seems rather difficult to explain. To help possible future identification and characterization of the SinC2H2 clusters, their infrared, Raman, and optical excitation spectra are calculated within the framework of DFT, using the 6-311+G(2d, p) basis set. It is expected that the present results would facilitate the exploitation of the well-known carborane and metallacarborane chemical properties and applications for the design and development of novel silicon-carbon-based composite materials.