The complex fac-[Ru(NO)Cl-2(kappa N-3(4),N-8,N-11(1-carboxypropyl)cyclam)]CI center dot H2O (1-carboxypropyl)cyclam = 3-(1,4,8,11-tetraazacyclotetradecan-1-yl)propionic acid) was prepared in a one pot reaction by mixing equimolar amounts of RuNOCl3 and (1-carboxypropyl)cyclam and was characterized by X-ray crystallography, electrospray ionization tandem mass spectrometry (ESI-MS/MS), elemental analysis, NMR, and electronic and vibrational (IR) spectroscopies. fac-[Ru(NO)Cl-2(kappa N-3(4) 4,N-8,N-11(l-carboxypropyl)cyclam)]Cl center dot H2O crystallizes in the triclinic, space group P (1) over bar, No. 2, with unit cell parameters of a = 8.501 (1) angstrom, b = 9.157(1) angstrom, c = 14.200(1) angstrom, alpha = 72.564(5)degrees, beta = 82.512(5)degrees, gamma = 80.308(5)degrees, and Z = 2. The Ru-N interatomic distance and bond angle in the [Ru-NO] unit are 1.739(2) angstrom and 167.7(2)degrees, respectively. ESI-MS/MS shows characteristic dissociation chemistry that initiates by HCl or NO loss. The IR spectrum displays a v(NO) at 1881 cm(-1) indicating a nitrosonium, character. The electronic spectrum shows absorptions bands at 264 nm (log epsilon = 3.27), 404 nm (log epsilon = 2.53), and 532 nm (log epsilon = 1.88). H-1 and C-13 NMR are in agreement with the proposed molecular structure, which shows a very singular architecture where the cyclam ring N (with the carboxypropyl pendant arm) is not coordinated to the ruthenium resulting in a kappa(3) instead of the expected kappa(4) denticity.