Chirality control of helixes with the Δ (P) or Λ (M) form is interesting in various fields such as extended metal atom chains (EMACs), in which the metal backbones are helically wrapped by four ligands. Herein, we report two EMACs, Δ-[Ni5((-)camnpda)4] and Λ-[Ni5((+)camnpda)4], whose chiralities are controlled by chiral ligands with naphthyridine and camphorsulfonyl groups. There is a large energy difference (108 kcal mol(-1)) between the two helical structures with one chiral ligand. Furthermore, the electron communication between [Ni2](3+) units is more pronounced than in [Ni5(bna)4Cl2](2+) (bna=binaphthyridylamido). The results demonstrate control of small-scale helical structure and set the stage for future development of chiral controlled base and nanoelectronic devices.

Novel chiral pentadentate ligands with naphthyridine and camphorsulfonyl groups have been designed and used to control the chirality of quadruple helixes of metal strings directly:Δ-Ni5((-)camnpda)4 (1) and Λ-Ni5((+)camnpda)4 (2). Compound 1 is a Δ form metal string complex with H2(-)camnpda and 2 is Λ form one with H2(+)camnpda. By X-ray single-crystal diffraction, The structures of the compound 1 and 2 are both 2,2-trans form in the same monoclinic space group C2 and have the similar unit cell. Further, it demonstrates that two metal strings are chiral isomers each other by CD spectra. In theoretical computation, the local minimum (Λ-Ni5((+)camnpda)4 with the Δ form) becomes energetically unfavourable by about 100 kcal/mol due to the strong steric repulsion introduced by the camphor groups. Finally, the racemic crystal is obtained with a 1:1 mixture of compounds 1 and 2 in triclinic space group P-1. Both the external dinickel distance in 1 and 2, about 2.280 Å, and the SQUID experiment reveal mixed valence [Ni2]3+ characters and the magnetic behaviors are anti-ferromagnetic (J = -55.0 cm-1 for 1 and -63.3 cm-1 for 2). In the electrochemistry, the three reversible oxidation waves in 1 and 2 are -0.13, 0.20 and 0.97 V.