The synthesis and characterization of several Cr(III) complexes of the constrained macrocyclic ligand 1,4-C-2-cyclam = 1,4,8,11-tetraazabicyclo[10.2.2]hexadecane is reported. The ligand appears to form only trans complexes, and the structure of trans- [Cr(1,4-C-2-cyclam)Cl-2]PF6 is presented. The constraint imposed by the additional C-2 linkage distorts the bond angles significantly away from the ideal values of 90 and 180degrees. The effect of the distortion is to enhance the aquation rate of trans-[Cr(1+C-2-cyclam)Cl-2](+) (k(obs) for trans-[Cr(1,4-C-2-cyclam)(H2O)(2)](3+) formation = 6.5 x 10(-2) s(-1), 0.01M HNO3, 25 degreesC) by over 5 orders of magnitude relative to trans-[Cr(cyclam)Cl-2](+). The complexes trans-[Cr(1,4-C-2-cyclam)Cl-2](+) and trans- [Cr(1,4-C-2-cyclam)(CN)(2)](+) are found to have extinction coefficients four to five times higher than their cyclam analogues, owed to the lack of centrosymmetry caused by the steric constraint, The trans-[Cr(1,4-C-2-cyclam)(CN)(2)](+) complex is a very weak emitter in aqueous solution with a broad room-temperature emission centered at 735 nm (tau = 0.24 mus). Extended photolysis (350 nm, 15 h) of trans-[Cr-(1,4-C-2-cyclam)(CN)(2)](+) in aqueous solution results in CN- ligand loss. This is in stark contrast to its unconstrained cyclam analogue, which is photoinert and has a room-temperature emission lifetime of 335 mus.