Synthesis and Crystal Structure of novel Mixed Ni2+8-x /Co2+x and Co2+4 Cubanes

<title>Abstract</title> <p> The mixed Co ²⁺ /Ni ²⁺ ) complex, [Ni _8-x Co _x L ₈ (CH ₃ COO) ₄ ] [BPh ₄ ] ₄ ·1.2 H ₂ O ( <bold>1</bold> ) where HL = 4-(salicylaldimine) antipyrine, was isolated as a yellow solid from the reaction of 4-(salicylaldimine)antipyrine, with mixed cobalt (II) acetate and nickel (II) acetate in ethanol. The pure cobalt [Co ₄ L ² ₄ (CH ₃ COO) ₂ ] [BPh ₄ ] ₂ ( <bold>2</bold> ) was isolated as a yellowish-orange solid from the reaction of cobalt (II) acetate and 4(2,4-dihydroxybezaldeimine) antipyrine (L ² H). Those complexes were characterized by Fourier-transform infra-red spectroscopy (FTIR), Ultra-Violet Visible spectroscopy (UV-Vis) and single crystal X-ray diffraction. The asymmetric unit of the crystal structure of the <bold>1</bold> is composed of two cationic [Ni _8-x Co _x L ₄ (CH ₃ COO) ₂ ] ²⁺ units (Z′ = 2) exhibiting a M ₄ O ₄ cubane-like core formed by the phenoxy oxygen atoms from the Schiff base ligand L bridging the metal sites. Three of the eight metal atoms in the asymmetric unit are modelled as partially occupied nickel and cobalt sites with an overall 7:1 ratio of nickel to cobalt. Two of the four-membered M-O-M-O rings in each cation are bridged by acetate groups perpendicular to each other. The structure of <bold>2</bold> crystallises with Z′ =1 and with similar cubane-like core of purely cobalt atoms. </p>