NiIV cubanes: synthesis and characterization of the [Ni4Se4(Se3)5(Se4)]4− and [Ni4Te4(Te2)2(Te3)4]4− anions

摘要: Abstract The compounds [NEt4]4[Ni4Se4(Se3)5(Se4)]·xNEt4Cl (x=0, 1) and [NEt4]4[Ni4Te4(Te2)2(Te3)4] have been prepared from the reaction in DMF of Ni(S2COEt)2 with Li2Se Se or Li2Te Te, respectively. These result spontaneous assembly reactions which NiII centers are oxidized to NiIV concomitant reduction Se- Te-containing species. anion [Ni4Se4(Se3)5(Se4)]4− possesses a Ni4Se4 cubane core has five Se32− chains one Se42− chain bridging Ni atoms on faces. [Ni4Te4(Te2)2(Te3)4]4− Ni4Te4 two Te22− opposite faces four Te32− remaining presence is necessitated by charge balance. As expected for such d6 systems diamagnetic. exhibits sharp, albeit complex, 77Se NMR spectrum fifteen resonances at δ 103, 134, 289, 361, 387, 401, 411, 470, 660, 680, 726, 749, 773, 789 804 ppm. simpler 125Te −632, −324, 65, 325 766 In anions each atom distorted octahedral environment, being coordinated three Te framework that bridge other atoms. While appear produce little strain core, distorts it, as evidenced NiNi distances, SecubSecub distances bond angles. contrast, distort TecubTecub angles; less strain. [NEt4]4[Ni4Se4(Se3)5(Se4)]·NEt4Cl crystallizes monoclinic space group C52h-P21/n a=21.817(4), b=14.319(1), c=26.421(5) A, β=112.69(2)°, V=7615 A3 Z=4 (−120 °C). triclinic Ci1-P 1 a=14.399(2), b=15.153(2), c=18.069(3) α=70.97(1), β=79.05(1), γ=74.20(1)°, V=3564 Z=2 (−167