Binuclear Pd(II) and Pt(II) complexes supported by rac-dpmppm (bis-[(diphenylphosphinomethyl)phenylphosphino] methane) in a triply-bridged Z-form, [M2Cl4(rac-dpmppm)] (M = Pd (3a), Pt (3b)), readily reacted with 2,6-xylyl isocyanide (XyINC) in the presence of NH4PF6 to afford [M2Cl2(rac-dpmppm)(XyINC)(2)](PF6)(2) (M = Pd (4a), Pt (4b)), in which each metal center accommodates one isocyanide ligand at the trans position to the inner P atom of dpmppm. Similarly, treatment of 3a and 3b with axially chiral (R/S)-1,1'-binaphthyl-2,2'-bisisocyanide (rac-Binac) in the presence of NH4OTf gave cyclic tetranuclear complexes, [{M2Cl2(rac-dpmppm)(rac-Binac)}(2)](OTf)(4) (M = Pd (5), Pt (8)), where two {M2Cl2 (rac-dpmppm)}(2+) fragments are connected by two rac-Binac ligands through chirality sorting of (R*,R*)-dpmppm and (R*)-Binac. Complex 5 could be transformed into the halide exchanged tetranuclear complexes, [{Pd2X2 (rac-dpmppm)(rac-Binac)}(2)](OTf)(4) (X = Br (6), I (7)), to show that the rectangular arrangement of four Pd(II) ions is elongated by repulsive interaction between halide ligands. By using (R)- and (S)-Binac, enantiopure Pd-4 complexes, [{Pd2Cl2 ((R*,R*)-dpmppm)((R*)-Binac)}(2) ](OTf)(4) (5(RR/R) and 5(SS/S)), were successfully isolated as pure crystalline forms, from which enantiopure (R,R)- and (S,S)-dpmppm were obtained by treatment with NaCN aqueous solution. Namely, optical resolution of rac-dpmppm was established through the tetranuclear Pd complexes, which is the first example for methylene- bridged polyphosphines, R2P(CH2PR)(n)CH2PR2 (n > 0). Furthermore, chiral octapalladium chains, [Pd-8((R*,R*)-dpmppm)(4)(N CCH3)(2)](BF4)(4) (2(RR) and 2(SS)), were synthesized by reacting enantiopure P-chiral dpmppm with [Pd-2(CH3CN)(6)](BF4)(2) and [Pd-2(dba)(3)]center dot C6H6 and were characterized by spectroscopic and X-ray crystallographic analyses, to determine the absolute configurational structures. The Pd-8 chains are the longest enantiopure chiral single-metal-atom chains structurally characterized, thus far, and the electronic structures were examined on the basis of DFT calculations of 2(RR).