The preparation and crystal structures of four ortho-carboranyl-nitrogen compounds, PhCboNdouble bond; length as m-dashN(C6H4Me-4) (1), PhCboNHNH(C6H4Me-4) (2), MeCboNHNHPh (3) and PhCboNHOH (4) (Cbo = 1,2-C2B10H10; nitrogen groups at cage carbon C1, Ph or Me at C2), the last as a 1,4-dioxane solvate, are reported. Comparisons of their structures with those of other ortho-carboranyl-nitrogen systems studied earlier reveal further correlations between their cage C–C and exo-C–N bond distances and bond orders. Substituent orientations and bond distances (cage C1–C2, exo-C1–N) in RCboNHR′′ systems (R = Ph or Me at C2) are consistent with dative π-bonding from a nitrogen lone pair into the cage carbon p-AO otherwise responsible for cage C1–C2 σ bonding. Their C1–C2 bond distances are remarkably sensitive to the planar (sp2) or pyramidal (sp3) nature of the NHR′′ group. The Ndouble bond; length as m-dashO and Ndouble bond; length as m-dashNR′ residues in RCboX prefer to be orientated in plane with the cage C1–C2 in contrast to the RCboNHR′′ systems. Correlations between their cage C–C and exo-C–N bond distances and the 11B NMR chemical shifts of their antipodal boron atoms reflect the π-bonding characteristics of the nitrogen substituent.