Reactions of [Ni(tren)(H2O)(2)]X(2) (tren = tris(2-aminoethyl)amine; X = Cl (1a), Br (1b); X(2) = SO4 (1c)) with mannose-type aldoses, having a 2,3-cis configuration (D-mannose and L-rhamnose), afforded {bis(N-aldosyl-2- aminoethyl) (2-aminoethyl)amine}nickel(II) complexes, [Ni(N,N’-(aldosyl)(2)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (2a), Br (2b), X(2) = SO4 (2c); aldosyl = L-rhamnosyl, X(2) = SO4 (3c)). The structure of 1c was confirmed by X-ray crystallography to be a mononuclear [(NiN4O2)-N-III] complex with the tren acting as a tetradentate ligand (1c . 2H(2)O : orthorhombic, Pbca, a = 15.988(2) Angstrom, b = 18.826(4) Angstrom, c = 10.359(4) Angstrom, V = 3118 Angstrom(3), Z = 8, R = 0.047, and R(w) = 0.042).Complexes 2a,c and 3c were characterized by X-ray analyses to have a mononuclear octahedral Ni(II) structure ligated by a hexadentate N-glycoside ligand, bis(N-aldosyl-2-aminoethyl) (2-aminoethyl)amine (2a . CH3OH: orthorhombic, P2(1)2(1)2(1), a = 16.005(3) Angstrom, b = 20.095(4) Angstrom, c = 8.361(1) Angstrom, V = 2689 Angstrom(3), Z = 4, R = 0.040, and R(w) = 0.027. 2c . 3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.93(2) Angstrom, b = 21.823(8) Angstrom, c = 9.746(2) Angstrom, V = 3176 Angstrom(3), Z = 4, R = 0.075, and R(w) = 0.080. 3c . 3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.560(4) Angstrom, b = 21.694(5) Angstrom, c = 9.786(2) Angstrom, V = 3091 Angstrom(3), Z = 4, R = 0.072, and R(w) = 0.079). The sugar part of the complex involves novel intramolecular sugar-sugar hydrogen bondings around the metal center. The similar reaction with D-glucose, D-glucosamine, and D-galactosamine, having a 2,3-trans configuration, resulted in the formation of a mono(sugar) complex, [Ni(N-(aldosyl)-tren)(H2O)(2)]Cl-2 (aldosyl = D-glucosyl (4b), 2-amino-2-deoxy-D-glucosyl (5a), and 2-amino-2-deoxy-D-galactosyl (5b)), instead of a bis(sugar) complex. The hydrogen bondings between the sugar moieties as observed in 2 and 3 should be responsible for the assembly of two sugar molecules on the metal center. Reactions of tris(N-aldosyl-2-aminoethyl)amine with nickel(II) salts gave the tris(sugar) complexes, [Ni(N,N’,N"-(aldosyl)(3)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (6a), Br (6b); L-rhamnosyl, X = Cl (7a), Br (7b); D-glucosyl, X = Cl (9); maltosyl, X = Br (10); and melibiosyl, X = Br (11)), which were assumed to have a shuttle-type C-3 symmetrical structure with Delta helical configuration for D-type aldoses on the basis of circular dichroism and C-13 NMR spectra. When tris(N-rhamnosyl)-tren was reacted with NiSO4 . 6H(2)O at low temperature, a labile neutral complex, [Ni(N,N’,N"-(L-rhamnosyl)(3)-tren)(SO4)] (8), was successfully isolated and characterized by X-ray crystallography, in which three sugar moieties are anchored only at the N atom of the C-1 position (8 . 3CH(3)OH . H2O: orthorhombic, P2(1)2(1)2(1), a = 16.035(4) Angstrom, b = 16.670(7) Angstrom, c = 15.38(1) Angstrom, V = 4111 Angstrom(3), Z = 4, R = 0.084, and R(w) = 0.068). Complex 8 could be regarded as an intermediate species toward the C-3 symmetrical tris(sugar) complexes 7, and in fact, it was readily transformed to 7b by an action of BaBr2.