The paper reports the synthesis, structural characterization, electrochemistry, ultrafast time-resolved infrared (TRIR) and transient absorption (TA) spectroscopy associated with two independent d(8) square planar Pt(II) diimine chromophores, Pt(dnpebpy)Cl-2 (1) and Pt(dnpebpy)(C=Cnaph)(2) (2), where dnpebpy = 4,4'-(CO2CH2-(BU)-B-t)2-2,2'-bipyridine and C Cnaph = naphthylacetylide. The neopentyl ester substitutions provided markedly improved complex solubility relative to the corresponding ethyl ester which facilitates synthetic elaboration as well as spectroscopic investigations. Following 400 nm pulsed laser excitation in CH2Cl2, the 23 cm(-1) red shift in the nu(c=o) vibrations in I are representative of a complex displaying a lowest charge-transfer-to-diimine (CT) excited state. The decay kinetics in 1 are composed of two time constants assigned to vibrational cooling of the (CT)-C-3 excited-state concomitant with its decay to the ground state (tau = 2.2 +/- 0.4 ps), and to cooling of the formed vibrationally hot ground electronic state (tau = 15.5 +/- 4.0 ps); we note that an assignment of the latter to a ligand field state cannot be excluded. Ultrafast TA data quantitatively support these assignments yielding an excited-state lifetime of 2.7 +/-0.4 ps for the 3CT excited-state of 1 and could not detect any longer-lived species. The primary intention of this study was to develop a Pt-II complex (2) bearing dual infrared spectroscopic tags (C C attached to the metal and C=O (ester) attached to the diimine ligand) to independently track the movement of charge density in different segments of the molecule following pulsed light excitation. Ferntosecond laser excitation of 2 in CH2Cl2 at 400 nm simultaneously induces a red-shift in both the nu(c=o) (-30 cm(-1)) and the nu(c=c) (-61 cm-1) vibrations. The TRIR data in 2 are consistent with a charge transfer assignment, and the significant decrease of the energy of the nu(c=c) vibration suggests a considerable contribution from the acetylide ligands in the highest occupied molecular orbital. Therefore, we assign the lowest energy optical transitions in 2 as a combination of metal-to-ligand and ligand-to-ligand charge transfers. The excited-state of 2 is emissive at FIT, with an emission maximum at 715 nm, quantum yield of 0.0012, and lifetime of 23 ns.