Post-synthetic modification of divalent nickel acetate cubanes with carboxylatesFootnote

Dedicated to Professor Rudi van Eldik on the occasion of his 70th birthday.

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• NiII complexes [Ni4(HL)4(O2CC3H7)2(OAc)2]·[Ni4(HL)4(OAc)4] crystallize as green blocks. Crystal data: C38H48N4Ni4O16, Mr = 1051.64 gmol−1; crystal dimensions 0.16×0.12×0.12 mm3; monoclinic, space group C2/c, a = 17.498(2), b = 13.948(1), c = 16.863(2) Å, α = γ = 90, β = 91.998(1)°, V = 4112.9(5) Å3; Z = 4; F(000) = 2176, ρcalcd = 1.698 gcm−3; Bruker Kappa APEX 2 /μS Duo diffractometer, MoKα radiation (λ = 0.71073 Å); T = 100(2) K; QUAZAR focusing Montel optics; θ range 5.8 ≤ 2θ ≤ 55.8°; section of the reciprocal lattice: –22 ≤ h ≤ 22, –18 ≤ k ≤ 18, –22 ≤ l ≤ 20. A semiempirical absorption correction based on multiple scans was applied (SADABS 2008/1 [28]; Tmin = 0.696, Tmax = 0.746); of 36722 measured reflections, 4902 were independent and 4319 had (Fo ≥ 4.0σ(F)); linear absorption coefficient 1.881 mm−1. The structure was solved by direct methods using SHELXTL NT 6.12 and refinement was performed with all data (298 parameters) by blocked matrix least-squares on F2 using SHELXL 2014/6 [27]. All non-hydrogen atoms were refined anisotropically; R1 = 0.0281 for I > 2σ(I) and wR2 = 0.0759 (all data); largest peak (0.525 eÅ−3) and hole (–0.359 eÅ−3). The positions of the O bound hydrogen atoms were taken from a difference fourier synthesis and their positional parameters were refined. All other hydrogen atoms were placed in positions of optimized geometry. The isotropic displacement parameters of all H atoms were tied to those of their corresponding carrier atoms by a factor of 1.2 or 1.5. The crystal contained the two compounds [Ni4(HL)4(O2CC3H7)2(O2CCH3)2]·[Ni4(HL)4(O2CCH3)4] in a 1:1 ratio with the terminal C3H7 groups of the asymmetric unit being occupied by only 50%. The complex molecule is situated on a crystallographic twofold rotation axis (Wyckoff position 4e) and possesses C2 molecular symmetry.
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