Three new N-alkyl substituted bis(imino)pyridine iron imide complexes, ((PDI)-P-iPr)FeNR ((PDI)-P-iPr = 2, 6-(2,6-Pr-i(2)-C6H3-N=CMe)(2)C5H3N; R = 1-adamantyl ((1)Ad), cyclooctyl ((Cy)Oct), and 2-adamantyl ((2)Ad)) were synthesized by addition of the appropriate alkyl azide to the iron bis(dinitrogen) complex, ((PDI)-P-iPr)Fe(N-2)(2). SQUID magnetic measurements on the isomeric iron imides, ((PDI)-P-iPr)FeN(1)Ad and ((PDI)-P-iPr)FeN(2)Ad, established spin crossover behavior with the latter example having a more complete spin transition in the experimentally accessible temperature range. X-ray diffraction on all three alkyl-substituted bis(imino)pyridine iron imides established essentially planar compounds with relatively short Fe-Nd-imide bond lengths and two-electron reduction of the redox-active bis(imino)pyridine chelate. Zero- and applied-field Mossbauer spectroscopic measurements indicate diamagnetic ground states at cryogenic temperatures and established low isomer shifts consistent with highly covalent molecules. For ((PDI)-P-iPr)FeN(2)Ad, Mossbauer spectroscopy also supports spin crossover behavior and allowed extraction of thermodynamic parameters for the S = 0 to S = 1 transition. X-ray absorption spectroscopy and computational studies were also performed to explore the electronic structure of the bis(imino)pyridine alkyl-substituted imides. An electronic structure description with a low spin ferric center (S = 1/2) antiferromagnetically coupled to an imidyl radical (S-imide = 1/2) and a closed-shell, dianionic bis(imino)pyridine chelate (S-PDI = 0) is favored for the S = 0 state. An iron-centered spin transition to an intermediate spin ferric ion (S-Fe = 3/2) accounts for the S = 1 state observed at higher temperatures. Other possibilities based on the computational and experimental data are also evaluated and compared to the electronic structure of the bis(imino)pyridine iron N-aryl imide counterparts.