A structureāproperty relationship study of neutral heteroleptic (1 and 2, [Ir(Cā§N)2(Lā§X)]) and homoleptic (3 and 4, fac-[Ir(Cā§N)3]) Ir(III) complexes (where Lā§X = anionic 2,2,6,6-tetramethylheptane-3,5-dionato-ĪŗO3,ĪŗO6 (thd) and Cā§N = a cyclometalating ligand bearing a pentafluorosulfanyl (āSF5) electron-withdrawing group (EWG) at the C4 (HL1) and C3 (HL2) positions of the phenyl moiety) is presented. These complexes have been fully structurally characterized, including by single-crystal X-ray diffraction, and their electrochemical and optical properties have also been extensively studied. While complexes 1 ([Ir(L1)2(thd)]), 3 (Ir(L1)3), and 4 (Ir(L2)3) exhibit irreversible first reduction waves based on the pentafluorosulfanyl substituent in the range of ā1.71 to ā1.88 V (vs SCE), complex 2 ([Ir(L2)2(thd)]) exhibits a quasi-reversible pyridineCā§N-based first reduction wave that is anodically shifted at ā1.38 V. The metal + Cā§N ligand oxidation waves are all quasi-reversible in the range of 1.08ā1.54 V (vs SCE). The optical gap, determined from the lowest energy absorption maxima, decreases from 4 to 2 to 3 to 1, and this trend is consistent with the Hammett behavior (Ļm/Ļp with respect to the metalācarbon bond) of the āSF5 EWG. In degassed acetonitrile, for complexes 2ā4, introduction of the āSF5 group produced a blue-shifted emission (Ī»em 484ā506 nm) in comparison to reference complexes [Ir(ppy)2(acac)] (R1, where acac = acetylacetonato) (Ī»em 528 nm in MeCN), [Ir(CF3-ppy) (acac)] (R3, where CF3-ppyH = 2-(4-(trifluoromethyl)phenyl)pyridine) (Ī»em 522 nm in DCM), and [Ir(CF3-ppy)3] (R8) (Ī»em 507 nm in MeCN). The emission of complex 1, in contrast, was modestly red shifted (Ī»em 534 nm). Complexes 2 and 4, where the āSF5 EWG is substituted para to the IrāCCā§N bond, are efficient phosphorescent emitters, with high photoluminescence quantum yields (Ī¦PL = 58ā79% in degassed MeCN solution) and microsecond emission lifetimes (ĻĪµ = 1.35ā3.02 Ī¼s). Theoretical and experimental observations point toward excited states that are principally ligand centered (3LC) in nature, but with a minor metal-to-ligand charge-transfer (3MLCT) transition component, as a function of the regiochemistry of the pentafluorosulfanyl group. The 3LC character is predominant over the mixed 3CT character for complexes 1, 2, and 4, while in complex 3, there is exclusive 3LC character as demonstrated by unrestricted density functional theory (DFT) calculations. The short emission lifetimes and reasonable Ī¦PL values in doped thin film (5 wt % in PMMA), particularly for 4, suggest that these neutral complexes would be attractive candidate emitters in organic light-emitting diodes.