Ni3Se(o-C6H4{CH2Se}2)3]2- und [Ni4(SeiC3H7)8], die ersten höherkernigen NickeI(II)-Komplexe mit vollständiger Selen-Ligandensphäre [Ni3Se(o-C6H4{CH2Se}2)3]2- and [Ni4(SeiC3H7)8], the First Polynuclear Nickel(II) Complexes with Complete Selenium Ligand Spheres

Abstract

Reaction of nickel(II) chloride with disodium ο-xylenediselenolate in methanol yields the trinuclear mixed selenide-selenolate complex anion [Ni3Se(ο-C6H4{CH2Se}2)3]2- (3) which was isolated both as tetramethylammonium and mixed sodium/tetraethylammonium salt of formula [Me4N]2[Ni3Se(ο-C6H4{CH2Se}2)3] · MeOH (1) and [Et4N]3Na[Ni3Se-(ο-C6H4{CH2Se}2)3]2- · 3MeOH · 3H2O (2), respectively. Crystals of 1 are triclinic, space group P1̄, a = 9.065(2), b = 13.281(3); c = 18.019(4) Å , α = 92.81(2), β = 97.55(2), γ = 105.09(2)° and Z = 2. 2 crystallizes in the rhom bohedral space group R3c with a = 20.305(5), c = 41.709(9) Å and Z = 6. The structures were refined to R = 0.0705 (1) and 0.0794 (2), respectively. Both compounds contain the complex anion [Ni3Se- (ο-C6H4{CH2Se}2)3]2- (3), which possesses the same principal structural features as the corresponding thiolato derivatives. Reaction of nickel(II) chloride with sodium iso-propane selenolate in methanol leads to the cyclic tetranuclear complex [Ni4(SeiC3H7)8] (4), which crystallizes in the monoclinic space group P2/n with a = 13.161(3), b = 10.464(2), c = 14.603(2) Å , β = 94.42(1)° and Z = 2. The structure refinement converged to R = 0.0541. 4 is isostructural with the corresponding thiolato compound. The introduction of selenium instead of sulfur ligands reduces the midpoint potential of the reversible metal-centered oxidation from +595 to +285 mV.