Reaction of the complex [{CpMo(CO)(2)}(2)(mu,eta(2)-P-2)] (1) with Cu-I halides leads to the quantitative formation of the novel one-dimensional linear polymers [CuX{Cp2Mo2(CO)(4)-(mu,eta(2):eta(1)-P-2)}](infinity) (X-Cl (4). Br (5), I (6)). The same products 4 and 5 were obtained when 1 was treated with CuCl2 and CuBr2, respectively. The solid-state structures are compared and their remarkable influence on the respective P-31 magic angle spinning (MAS) NMR spectra is interpreted with the help of density functional theory (DFT) calculations on the model compounds [{(CuX)(2){Cp2Cr2-(CO)(4)(mu,eta(2):eta(1)-P-2)}(2)}(3)] (X-Cl (4a), Br (5a)) in which the molybdenum atoms are replaced by their lighter homologue chromium.