Treatment of (trimpsi)V(CO)(2)(NO) (trimpsi = (BuSi)-Bu-t(CH2PMe2)(3)) with 1 equiv of PhlCl(2) or C2Cl6 or 2 equiv of AgCl affords (trimpsi)V(NO)Cl-2 (1) in moderate yields. Likewise, (trimpsi)V(NO)Br-2 (2) and (trimpsi)V(NO)\(2) (3) are formed by the reactions of (trimpsi)V(CO)(2)(NO) with Br-2 and l(2), respectively. The complexes (trimpsi)M(NO)l(2)(PMe3) (M = Nb, 4; Ta, 5) can be isolated in moderate to low yields when the (trimpsi)M(CO)(2)(NO) compounds are sequentially treated with 1 equiv of l(2) and excess PMe3. The reaction of (trimpsi)V(CO)(2)(NO) with 2 equiv of CINO forms 1 in low yield, but the reactions of (trimpsi)M(CO)(2)(NO) (M = Nb, Ta) with 1 equiv of CINO generate (trimpsi)M(NO)(2)Cl (M = Nb, 6; Ta, 7). Complexes 6 and 7 are thermally unstable and decompose quickly at room temperature; consequently, they have been characterized solely by IR and P-31{H-1} NMR spectroscopies. All other new complexes have been fully characterized by standard methods, and the solid-state molecular structures of 1.3CH(2)Cl(2), 4.(3/ 4)CH2Cl2, and 5.THF have been established by single-crystal X-ray diffraction analyses. A convenient method of generating (ClNO)-N-15 has also been developed during the course of these investigations.