Synthetic studies are presented addressing the oxidative decarbonylation of molybdenum and tungsten complexes supported by the encumbering m-terphenyl isocyanide ligand CNArDiPP2 (Ar-DiPP2 = 2,6-(2,6-(i-Pr)(2)C6H3)(2)C6H3). These studies represent an effort to access halide or pseudohalide M/CNArDiPP2 species (M = Mo, W) for use as precursors to low-coordinate, low-valent group 6 isocyanide complexes. The synthesis and structural chemistry of the tetra- and tricarbonyl tungsten complexes trans-W(CO)(4)(CNArDiPP2)(2) and trans-W-(NCMe)(CO)(3)(CNArDiPP2)(2) are reported. The acetonitrile adducts trans-M(NCMe)(CO)(3)(CNArDiPP2)(2) (M = Mo, react with I-2 to form divalent, diiodide complexes in which the extent of decarbonylation differs between Mo and W. In the molybdenum example, the diiodide, dicarbonyl complex MoI2(CO)(2)(CNArDiPP2)(2) is generated, which has an S = 1 ground state in solution. Paramagnetic group 6 MX2L4 complexes are rare, and the structure of MoI2(CO)(2)(CNArDiPP2)(2) is discussed in relation to other diamagnetic and Cu-distorted MX2L4 complexes. Diiodide MoI2,(CO)(2)(CNArDiPP2)(2) reacts further with I-2 to effect complete decarbonylation, producing the paramagnetic tetraiodide complex trans-MoI4(CNArDiPP2)(2). The reactivity of the trans-M(NCMe)(CO)(3)(CNArDiPP2)(2) (M = Mo, W) complexes toward benzoyl peroxide is also surveyed, and it is shown that dicarboxylate complexes can be obtained by oxidative or salt-elimination routes. The reduction behavior of the tetraiodide complex trans-MoI4(CNArDiPP2)(2) toward Mg metal and sodium amalgam is studied. In benzene solution under N-2, trans-MoI4(CNArDiPP2)(2) is reduced by Na/Hg to the e-arene-dinitrogen complex, (eta(6)-C6H6)Mo(N-2)(CNArDiPP2)(2). The diiodide-e-benzene complex (eta(6)-C6H6)MoI2(CNArDiPP2)(2) is an isolable intermediate in this reduction reaction, and its formation and structure are discussed in context of putative low-coordinate, low-valent molybdenum iso cyanide complexes.