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Copper(I) 1,1-dithiolate cluster transformations. Synthesis of [Bu4N]6[Cu6(S,i-MNT)6], i-MNT=[S2CC(CN)2]−, from [Bu4N]4[Cu8(i-MNT)6] with sulfur. Reaction of the cyclic hexanuclear complex with phosphine to give the tetrahedral [Bu4N]4[Cu4(i-MNT)4] which oxidizes in solution to give the homocubane [Bu4N]4[Cu8(i-MNT)6] and [Bu4N]2[Cu(i-MNT)2]

1998; Elsevier BV; Volume: 174; Issue: 1 Linguagem: Inglês

10.1016/s0010-8545(98)00049-6

1873-3840

C. W. Liu, Richard J. Staples, John P. Fackler,

Metal-Organic Frameworks: Synthesis and Applications

The novel sulfur-rich cluster anion, [Cu6(S,i-MNT)6]6−, 2, is obtained from the reaction of the homocubane, [Cu8(i-MNT)6]4−, 1, and powdered sulfur in acetonitrile solution under basic conditions. Compound 2 crystallizes in the R bar 3 space group with a=33.519(5) Å, b=33.519(5) Å, c=11.748(2) Å, γ=120°, and V=11431(3) Å3. The molecule contains six trigonally coordinated copper atoms linked together into a 12 membered ring by the six sulfur atoms of the bridging sulfur-rich i-MNT ligands. Six CuI atoms are located at the vertices of a nearly regular hexagon. The mean distance between the two planes of alternating CuI atoms is 0.345(2) Å. When 2 reacts with triphenylphosphine, a sulfur atom is removed from the disulfide containing ligands to give [Cu4(i-MNT)4]4−, isolated as the [nBu4N]+ salt, 4. This tetranuclear species also can be synthesized directly from [Cu(CH3CN)4][PF6] and [nBu4N]2[i-MNT] in acetonitrile. Compound 4 crystallizes in the C2/c space group with a=38.351(6) Å, b=38.468(8) Å, c=32.685(5) Å, β=124.94(1)°, and V=39527(12) Å3. The anion reveals discrete units of four copper atoms at the vertices of a distorted tetrahedron, bound to four i-MNT groups acting as “tridentate” (μ1, μ2) ligands. The cluster anion also is found as [BzEt3N][nBu4N]3 [Cu4(i-MNT)4], 5. Compound 5 crystallizes in the C2/c space group with a=27.306(7) Å, b=14.127(3) Å, c=27.868(6) Å, β=121.22(2)°, and V=9193(4) Å3. In solution the tetranuclear species transforms with oxidation into the Cu8 homocubane, 1, and the paramagnetic anion [CuII(i-MNT)2]2−, isolated as the [nBu4N]+ salt, 3. Spectroscopic evidence, including UV–Vis and 13C−NMR, for the cluster transformation is presented. Compound 3 crystallizes in the P21/n space group with a=10.036(1), b=16.724(2), c=14.234(1), β=91.37(9), and V=2388(0). The anion in 3 is planar with the copper atom located on the center of symmetry. Pertinent 13C chemical shifts (ppm) and absorption maxima (nm) with extinction coefficients in parentheses are as follows: 1, 14, 20, 24, 59, 79.8, 116.5, 197.7; 404 (ϵ=86 000 M−1 cm−1), 320 (ϵ=60 000 M−1 cm−1). 2, 14, 20, 24, 59, 61.7, 118.5, 119.5, 158; 380 (ϵ=85 000 M−1 cm−1), 350 sh (ϵ=74 000 M−1 cm−1). 3, 450 (ϵ=15 000 M−1 cm−1), 350 (ϵ=80 000 M−1 cm−1), 340 sh (ϵ=43 000 M−1 cm−1), 315 sh (ϵ=25 000 M−1 cm−1). 4, 14, 20, 24, 59, 70.8, 120, 209.5; 380 (ϵ=92 000 M−1 cm−1).