Synthesis and characterization of some group 1 and 2 metal derivatives of the crowding terphenyl thiolate and selenolate ligands -EC6H3-2,6-Trip2 (E=S or Se; Trip=2,4,6-i-Pr3C6H2-)

Article abstract of DOI:10.1016/s0020-1693(97)05657-0

The synthesis and characterization of the monomeric magnesium thiolate Mg {SC₆H₃-2,6-Trip₂}₂ (1) (Trip=2,4,6-i-Pr₃C₆H_2-), the new selenol HSeC₆H₃-2,6-Trip₂ (2), three of its alkali metal derivatives (MSeC₆H₃-2,6-Trip₂) (M=K, 3·PhMe, 3·Et₂O, Rb, 4·PhMe) and the heterometallic thiolate RbAlMe₂(SC₆H₃-2,6-Trip₂)₂ (5) are described. Compound 1 was synthesized by the reaction of commercially available 'MgBu₂' with 2 equiv. of HSC₆H₃-2,6-Trip₂. The new selenol 2 was obtained from the reaction of elemental selenium with LiC₆H₃-2,6-Trip₂. The potassium and rubidium derivatives 3 and 4 were isolated by direct reaction of the metals with the selenol whereas 5 is formed by an exchange reaction between the corresponding rubidium thiolate and AlMe₃. The compounds were characterized by ¹H, ¹³C and ⁷⁷Se NMR and IR spectroscopy, and by X-ray crystallography. Compound 1 crystallizes as a unique monomer with an S-Mg-S angle of 166.8(2)°. Compounds 3·PhMe and 4·PhMe crystallize as isomorphous dimers with M₂Se₂ cores. In these compounds each potassium or rubidium interacts in a π-fashion with two ortho aryl groups as well as σ-bonding to the chalcogens. The π-interaction is retained even in the presence of donor solvents. Thus, the ether solvate 3·Et₂O is obtained by recrystallization of 3·PhMe from diethyl ether. Metal aryl interactions also are observed in the rubidium aluminate 5 which crystallizes with a planar RbAlS₂ core. Crystal data at 130 K are as follows: Mg(SC₆H₃-2,6-Trip₂)₂ (1), a=10.417(1), b=11.644(1), c=14.545(2) A?, α=69.536(8), δ=75.91(1), γ=80.26(1)°, V=1596.2(3) A?³, space group P1?, Z=1, R₁=0.043; (KSeC₆H₃-2,6-Trip₂)₂·PhMe (3·PhMe), a=13.842(3), b=15.124(3), c=17.776(3) A?, α=83.04(2), β=85.62(2), γ=89.64(2)°, V=3683(1) A?³, space group P1?, Z=2, R₁=0.090; (RbSeC₆H₃-2,6-Trip₂)₂·PhMe (4·PhMe), a=13.959(2), b=15.179(1), c=17.713(2) A?, α=97.636(7), β=93.320(8), γ=90.462(8)°, V=3713.3(6) A?³, space group P1?, Z=2, R₁=0.050; RbAlMe₂(SC₆H₃-2,6-Trip₂) ₂·C₆H¹⁴ (5), a=26.610(5), b=13.142(1), c=21.575(5) A?, β=99.37(2)°, V=7444(3) A?³, space group C2/c, Z=4, R₁=0.047.