Ca4Ni3C5, a Carbide with an One-Dimensionally Infinite Nickel-Carbon Polyanion, and CaPd3C, a Perovskite Carbide
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چکیده
The new carbides C a4N i3C 5 and C aP d3C were prepared from the elemental com ponents by arc melting and subsequent annealing a t 700 °C. The structure o f C a4N i3C 5 was determ ined from single-crystal X -ray data. It crystallizes in the m onoclinic space group C 2/m , a = 1108.7(3) pm, b = 377.1(1) pm , c = 983.9(2) pm, ß = 112.58(2)°, Z = 2. Pow der data show C aPd3C to have the cubic perovskite structure w ith a 414.1(2) pm. While the carbon atom s in C aPd3C are isolated from each other, they form C2 pairs in Ca4N i3C5 with the typical triple bond C C distance o f 120(2) pm. In addition to the C2 pairs there are isolated carbon atom s in distorted octahedral coordination o f four Ni atom s form ing a square, which is augm ented by two Ca atom s. In the one-dim ensionally infinite polyanion [Ni3C 5]„8"“ these C N i4 squares are condensed by sharing two N i atom s at opposite corners o f the squares. A C2 pair is a t tached to each o f the o ther Ni atom s in an end-on configuration. Chemical bonding within this polyanion is briefly discussed on the basis o f the 18and 8-electron rules for the Ni and C atom s, respectively. C a4N i3C 5 is diam agnetic w ith a susceptibility o f / = -1 2 (± 5 )x 10"9 m 3/ mol.
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