Syntheses of novel 18- and 16-electron monocarbon closo-rhodacarboranes derived from nido-B10H12-CNMe(3) are reported. closo-2,7-(PPh(3))(2)-2-H-2Cl-1-(NMe(3))-2,1-RhCB10H9 (3) and closo-2-(PPh(3))-2-Cl-1-(NMe(3))-2,1-RhCB10H10 (4) were prepared by heating Rh(PPh(3))(3)Cl with nido-B(10)H(12)CNMe(3) in methanol. The molecular structure of 3 was determined by X-ray diffraction and represents the first structurally characterized hydride complex within the family of mononuclear icosahedral monocarbon metallacarboranes.