The aminobis(phosphonite) PhN(P(OC6H4OMe-o)(2))(2) (PNP; 1) reacts with 2 equiv of CuI to give a binuclear complex, Cu-2(mu(2)-I)(2)(NCCH3)(2)(mu-PNP) (2), whereas similar reactions with CuCl and CuBr furnish tetranuclear "ladder"-type complexes, Cu-4(mu(2)-X)(2)(mu(3)-X)(2)(mu-PNP)(2) (3, X = Cl; 4, X = Br), in excellent yield. The complex 2 when heated under vacuum turns into the tetranuclear complex 5 in a reversible fashion. Similarly, the complexes 3 and 4 on dissolution in CH3CN dissociate reversibly into the corresponding binuclear complexes from which the tetrameric complexes can be readily regenerated. Treatment of 2 with excess of pyridine produces the heterosubstituted derivative, Cu-2(mu(2)-I)(2)(C5H5N)(2)(mu-PNP) (6). The interaction of 2 with 2,2'-bipyridine in 1:1 and 1:2 ratios produces the mono- and disubstituted derivatives, Cu-2(mu(2)-I)I(C10H8N2)(mu-PNP) (7) and [Cu-2(mu(2)-I)(C10H8N2)(2)(mu-PNP)]I (8), respectively. The chloro and bromo analogues of 7 are prepared by treating the tetranuclear derivatives 3 and 4 with 2,2'-bipyridine. Reaction of 2 with 4,4'-bipyridine in the presence of AgOTf gives the cationic complex [Cu-4(NCCH3)(4)(C10H8N2)(2)(mu-PNP)(2)](OTf)(4) (9), whereas the complex [Cu-2(NCCH3)(2)(mu-PNP)(2)](OTf)(2) (10) was obtained from the reaction of 2 with 1 equiv of 1 and AgOTf. The reactions of 3 and 4 with 2 equiv of 4,4'-bipyridine in acetonitrile afford one-dimensional copper(I) coordination polymers [Cu-2(mu(2)-X)(2)(mu-PNP)(C10H8N2)](n) (13, X = Cl; 14, X = Br). The molecular structures of 2-4, 6-8, 12, and 14 are confirmed by X-ray crystallography.