Crystal structure of μ-carbonato-bis[diaqua(N,N,N′,N′-tetramethylethylenediamine)nickel(II)] perchlorate, [Ni(C6H16N2)(H2O)2(CO3)0.5]2(ClO4)2

C13H40Cl2N4Ni2O15, orthorhombic, P21212 (no. 18), a = 11.684(2) Å, b = 19.076(3) Å, c = 6.297(1) Å, V = 1403.5 Å, Z = 2, Rgt(F) = 0.043, wRref(F) = 0.107, T = 296 K. Source of material N,N,N',N'-tetramethylethylenediamine (tmen, 1.51 g, 13 mmol) was added to an aqueous solution (30 ml) of Ni(ClO4)2 · 6H2O (3.65 g, 10 mmol), followed by the addition of Na2CO3 (0.71g, 6.7 mmol) dissolved in 10 ml of water and stirred at room temperature for 30 minutes. The resulting green solution was filtered and slowly dried to give the title compound. Recrystallization from ethanol gave blue crystals suitable for X-ray crystallographic analysis. Experimental details All non-hydrogen atoms have been modelled anisotropically using SHELXTL [1] with absorption corrected data, except for carbon (C1) and oxygen (O1) which are located on the crystallographic two-fold axis of symmetry. The carbon hydrogen atoms were fixed at calculated positions [d(C—H) = 0.96 Å for CH3, d(C—H) = 0.97 Å for CH2] after the least squares cycles and the water hydrogens were located in the fourier maps but not refined. The perchlorate molecule was modelled as disordered over two sites (as Cl1, Cl2, etc.) with the respective occupancies equal to 0.51(1) and 0.49(1). Discussion The title crystal structure has been determined, by a single-crystal X-ray analysis, to be a perchlorate derivative of the binuclear complex nickel-containing cation (figure, top). It is noteworthy that the same building blocks result in hexameric cluster complexes when the counter anions are halides such as Br− [2]. The Ni dimer is located on a 2-fold axis of symmetry. The Ni atom is in distorted octahedral coordination. The largest distortion being due to the bidentate coordination of the carbonate anion, i.e. with the (O1−Ni1−O2) angle equal to 62.7(2)°. The water oxygen atoms coordinate at significantly different bond distances, d(Ni1—O3) 2.113(4)Å and d(Ni1—O4) 2.055(4)Å, due to the different trans-influences of N1 and O2, respectively. The tmen nitrogen atoms coordinate with about equal bond distances, i.e. d(Ni1—N1) = 2.118(6)Å and d(Ni1—N2) = 2.105(6)Å. The carbonate anion coordinates to the Ni centers with the different Ni—O distances, d(Ni1—O1) = 2.0651(8) Å and d(Ni1—O2) = 2.163(4)Å, in a similar way to the reported analogous [3,4]. The coordination mode of the carbonate (here) is the most common of the twelve possible modes reported [5]. The hydrogen bond network is shown in the bottom figure making a columnar polymer in the lattice (respective symmetry relations: primed, double primed and asterix are related by: x,y,1+z; {x,y,1+z & −x,−y,z}; and −x,− y,z), in which the water molecules are H-bonded to both neighbouring carbonate oxygen atoms and perchlorate oxygen atoms. The dis tance O2(CO3 ) · · ·O4 ' (H2O) is 2.666(6) Å , O3(H2O)···O5'(ClO4) is 2.91(2) Å and O3(H2O)···O7(ClO4) is 2.92(4) Å. As a result, 12-membered macrocycles (−C1−O2− H4'−O4'−Ni1'−O2'−C1'−O2''−Ni''−O4''−H4''−O2*−) are formed. In addition, two parallel water-perchlorate networks (e.g., −O7−H1−O3−H2−O5'−O7'−H1'−O3'−) run in the horizontal direction (figure bottom). Z. Kristallogr. NCS 224 (2009) 131-132 / DOI 10.1524/ncrs.2009. 0061 131 © by Oldenbourg Wissenschaftsverlag, München