With the new substituted pyrazine ligand pyrazine-2,3-dicarboxylic acid bis[(pyridin-2-ylmethyl)amide], H(2)L, a binuclear complex [Cu(2)(LH)(Cl(3))(H(2)O)].H(2)O (1) and two [2 x 2]G grid complexes, [[Cu(4)(LH)(4)](ClO(4))(4)].5CH(3)OH.4H(2)O (2) and [[Ni(4)(LH)(4)]Cl(4)].5CH(3)CN.13H(2)O (3), have been synthesized and characterized spectroscopically and crystallographically. The ligand H(2)L crystallized in the triclinic space group P1, with a = 4.9882(7) A, b = 12.079(2) A, c = 14.454(2) A, alpha = 107.08(2) degrees, beta = 98.61(2) degrees, gamma = 97.54(2) degrees, V = 808.8(2) A(3), Z = 2, R1 = 0.0747, and R(w) = 0.1829 for 1319 observed reflections [I > 2 sigma(I)]. The molecule is L-shaped with a strong intramolecular bifurcated hydrogen bond in half of the molecule. In the crystal the molecules are linked by an intermolecular hydrogen bond to form a 1D polymer. The binuclear complex [Cu(2)(LH)(Cl(3))(H(2)O)].H(2)O (1) crystallized in the monoclinic space group P2(1)/a, with a = 8.6859(7) A, b = 28.060(2) A, c = 9.5334(9) A, beta = 107.89(1) degrees, V = 2211.2(3) A(3), Z = 4, R1 = 0.039, and R(w) = 0.097 for 1408 observed reflections [I > 2 sigma(I)]. There are two independent copper atoms both having square pyramidal geometry. Both coordinate to a pyrazine, a pyridine, and an amide N atom. Two chlorines complete the coordination sphere of one of the copper atoms, while one chlorine atom and a water molecule complete the coordination sphere of the other. The copper(II) [2 x 2] grid complex [[Cu(4)(LH)(4)](ClO(4))(4)].5CH(3)OH.4H(2)O (2) crystallized in the triclinic space group P1, with a = 17.1515(14) A, b = 17.7507(13) A, c = 19.3333(15) A, alpha = 67.34(1) degrees, beta = 69.79(1) degrees, gamma = 71.50(1) degrees, V = 4980.3(7) A(3), Z = 2, R1 = 0.083, and R(w) = 0.207 for 5532 observed reflections [I > 2 sigma(I)]. The four Cu(II) atoms are octahedrally coordinated by two pyrazine, two pyridine, and two amide N atoms and occupy the corners of a [2 x 2] grid with edge lengths, Cu...Cu, varying from 7.01 to 7.39 A. The nickel(II) [2 x 2] grid complex [[Ni(4)(LH)(4)]Cl(4)].5CH(3)CN.13H(2)O (3) crystallized in the monoclinic space group C2/c, with a = 16.3388(10) A, b = 29.754(2) A, c = 20.857(1) A, beta = 101.845(1) degrees, V = 9923.6(12) A(3), Z = 4, R1 = 0.050, and wR2 = 0.101 for 3391 observed reflections [I > 2 sigma(I)]. Here the complex possesses C(2) symmetry and again each metal atom is octahedrally coordinated to two pyrazine, two pyridine, and two amide N atoms. They occupy the corners of a [2 x 2] grid with an average edge length, Ni.Ni, of 6.97 A. Of the four anions (ClO(4)(-)'s in 2 and Cl(-)'s in 3) required to equilibrate the charges in the grid complexes, two are encapsulated, one above and one below the plane of the four metal atoms. The remaining two anions are located between the "wings" of the ligands. Magnetic susceptibility measurements indicate that the binuclear complex 1 is antiferromagnetic, with a J value of -15.07 cm(-1). This is larger than the J values found for the Cu(II...

The title compounds, C 11 H 10 N 4 O (HL1) and C 11 H 10 N 4 O (HL2), are pyridine 2-ylmethyl and 4-ylmethyl derivatives, respectively, of pyrazine-2-carboxamide. HL1 was measured at 153 K and crystallized in the monoclinic space group P2 1 /c with Z = 4. There has been a report of the same structure measured at room temperature but assumed to crystallize in the triclinic space group P1 with Z = 4 [Sasan et al. (2008). Monatsh. Chem. 139,[773][774][775][776][777][778][779][780]. In HL1, the pyridine ring is inclined to the pyrazine ring by 61.34 (6) , while in HL2 this dihedral angle is 84.33 (12) . In both molecules, there is a short N-HÁ Á ÁN interaction involving the pyrazine carboxamide unit. In the crystal of HL1, molecules are linked by N-HÁ Á ÁN hydrogen bonds, forming inversion dimers with an R 2 2 (10) ring motif. The dimers are linked via bifurcated-acceptor C-HÁ Á ÁO hydrogen bonds, forming sheets lying parallel to (102). The sheets are linked via C-HÁ Á ÁN hydrogen bonds, forming a three-dimensional structure. In the crystal of HL2, molecules are linked by N-HÁ Á ÁN and C-HÁ Á ÁN hydrogen bonds to form chains propagating along [010]. The chains are linked via C-HÁ Á ÁO hydrogen bonds, forming sheets lying parallel to (100). Within the sheets there areinteractions involving neighbouring pyrazine rings [inter-centroid distance = 3.711 (15) Å ]. Adjacent sheets are linked via parallel slipped -interactions involving inversion-related pyridine rings [inter-centroid distance = 3.6395 (17) Å ], forming a three-dimensional structure. Chemical contextThe title compounds form part of a series of ligands synthesized in order to study their coordination chemistry with 3d transition metals (Cati, 2002).They have been used to construct coordination polymers and multi-nuclear compounds, and to study their magnetic ISSN 1600-5368 properties (Cati et al., 2004). Similar ligands have been synthesized by other groups who have studied, for example, the magnetic properties of some copper(II) complexes (Hausmann et al., 2003;Kingele et al., 2007). Structural commentaryThe molecular structure of ligand HL1 is illustrated in Fig. 1. HL1 was measured at 153 K and crystallized in the monoclinic space group P2 1 /c with Z = 4. The angle is 91. 461 (11) and the systematic absences, the R int value (0.0348) and the successful refinement {R1 [I > 2(I)] = 0.0319} clearly show that at 153 K the space group is monoclinic P2 1 /c. The same structure measured at room temperature was reported to crystallize in the triclinic space group P1 with Z = 4 (Sasan et al., 2008). However, the three cell angles are close 90 (2) [ = 91.802 (6), = 89.834 (7), = 91.845 (6) ] and the crystal used was a very narrow needle. The final R1 [I > 2(I)] factor was rather high at 0.0699, hence it is possible that the choice of crystal system and space group are incorrect. However, this could not be confirmed when analysing the coordinates using the AddSymm routine in PLATON (Spek, 2009).In the molecule of HL1 there is a short N-HÁ Á ÁN hydrogen ...

In the complex, bis­[N,N′‐bis­(pyridin‐2‐yl­methyl)­pyrazine‐2,3‐dicarbox­amide]­cobalt(III) tris­(perchlorate) aceto­nitrile 3.5‐solvate, [Co(C18H16N6O2)2](ClO4)3·3.5CH3CN, the result of the reaction of Co(ClO4)2 with the ligand N,N′‐bis­(pyridin‐2‐yl­methyl)­pyrazine‐2,3‐dicarbox­amide, the CoII atom has been oxidized to CoIII and has a slightly distorted octahedral coordination geometry. In each ligand, one amide NH proton has been transferred to a non‐coordinated pyridine ring, thereby producing a zwitterion. This proton is hydrogen bonded to the carbonyl O atom of the adjacent deprotonated (pyridin‐2‐yl­methyl)­amide substiutent involved in coordin­ation.

Key indicatorsSingle-crystal X-ray study T = 153 K Mean '(C±C) = 0.002 A Ê R factor = 0.032 wR factor = 0.079 Data-to-parameter ratio = 10.1For details of how these key indicators were automatically derived from the article, see