Pt(II) complexes bearing imidazolylidene–pyridylidene (impy) and dianionic biazolate chelates were synthesized, for which the end products depend on the alkyl substituents of the impy chelate. Treatment of Pt(DMSO)₂Cl₂ with dimethyl substituted imidazolium–pyridinium pro-ligand Me₂impy(PF₆)₂, followed by addition of 5,5′-(1-methylethylidene)-bis-(3-trifluoromethyl-1H-pyrazole) (mepzH₂), 5,5′-di(trifluoromethyl)-3,3′-bis-pyrazole (bipzH₂), and 5,5′-di(pentafluoroethyl)-3,3′-bis-pyrazole (biepzH₂), afforded Pt(II) complexes [Pt(Me₂impy)(mepz)] (1), [Pt(Me₂impy)(bipz)] (2) and [Pt(Me₂impy)(biepz)] (3), respectively. In contrast, reactions with ethyl and isopropyl substituted Et₂impy(PF₆)₂ and Pr₂impy(PF₆)₂ and with bipzH₂ gave [Pt(EtimHpy)(bipz)] (4) and [Pt(PrimHpy)(bipz)] (5) respectively, where notable alkyl-to-hydrogen transformations on the pyridylidene fragment took place. The reaction of Pt(DMSO)₂Cl₂ with Et₂impy(PF₆)₂ followed by addition of (biepzH₂) gave two products [Pt(Et₂impy)(biepz)] (6) and [Pt(EtimHpy)(biepz)] (7). Single crystal X-ray diffraction analyses of 1, 2 and 5 revealed negligible intermolecular Pt⋯Pt interactions. Hybrid-DFT and TD-DFT computations were carried out on 1, 2 and 5 to model the observed crystal structures and explain the photophysical data successfully. Organic light emitting diodes (OLEDs) were fabricated from complexes 4 or 5 using a multiple layered device architecture. The associated OLED performances (i.e. η_max = 12.5%, 11.2%, η_L = 44.0 cd A⁻¹, 40.6 cd A⁻¹, and η_P = 28.0 lm W⁻¹, 25.8 lm W⁻¹ for 4 and 5) confirmed their suitability in serving as potential OLED phosphors.