2. Computational details
Quantum chemical calculations on Pt(CN)n(n = 1–6) complexes and their corresponding supersalts and superacids were performed utilizing DFT [43,44] with B3LYP [45,46]. SDD basis set [47,48] supplemented with Stuttgart/Dresden relativistic effective core potential was used for Pt atom, whereas, 6–311+G(d) basis set [49–51] was used for CN moieties. Workers [52,53] have used similar approach to perform geometry optimizations obtaining better results. All calculations were carried out using the Gaussian 16W software package [54] utilizing the linear combination of atomic orbital–molecular orbital (LCAO–MO) technique. In current investigation, all possible minimum energy structures of Pt(CN)n complexes were modelled. The structures were analyzed by using the GaussView 6 [55] software.
EA values were obtained by calculating the energy difference between optimized structures of neutral and anionic forms of Pt(CN)n complexes. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were visualized by using the GaussView 6 [55] software. The HOMO and LUMO are frontier orbitals which play an important role in determining the chemical reactivity of complexes. Percentage (%) contribution by each element to various orbitals of Pt(CN)n complexes was determined by using the GaussSum 2.2 [56] program. The program utilizes the output files generated by Gaussian 16W software package [54] to determine the elemental percentage (%) contributions in the orbitals. Parameters relevant for probing the properties of supersalts and superacids corresponding to Pt(CN)n complexes were also calculated byGaussian 16W software package [54] as discussed in following section.