Synthesis and X-ray crystal structures of the mono- and binuclear arylmanganate complexes [{Li(Et2O)2}2Mn2Ph6], [Li(THF)4]2[Mn2Ph6], and [Li(THF)4][MnMes3]

Article abstract of DOI:10.1021/om00098a018

The synthesis and X-ray crystal structures of the arylmanganate complexes [{Li(Et₂O)₂}₂Mn₂Ph₆] (1), [Li(THF)₄]₂[Mn₂Ph₆] (2), and [Li(THF)₄][MnMes₃] (3) are reported. They are the first X-ray structural characterizations of compounds of the type LiMnR₃ which are, in conjunction with neutral organomanganous species, of growing importance in organic synthesis. The complex LiMnPh₃ , derived from a manganese dihalide and 3 equiv of PhLi, crystallizes as a centrosymmetric dimer in the case of both 1 and 2. The structure of 1 may be described as a linear array of the four metals LiMnMnLi. Each metal is located at the centers of four edge-sharing distorted tetrahedra. Thus, both manganese atoms are surrounded by four bridging phenyls, and the two outer lithiums are coordinated to two bridging phenyls and two ethers. The ionic complex 2 has a similar structure except that the more strongly coordinating THF's effect separation of the lithium ions as [Li(THF)₄]⁺ leaving the free dimeric [Mn₂Ph₆]^2- ion with a core structure similar to that seen in 1. Use of the bulkier mesityl group affords the mononuclear ionic species [Li(THF)₄][MnMes₃] (Mes = 2,4,6-Me₃C₆H₂) featuring a trigonal-planar structure for the [MnMes₃]^- ion. Crystal data with Mo Kα (λ = 0.71069 A?) radiation at 130 K are as follows: 1, a = 14.764 (6) A?, b = 15.496 (6) A?, c = 21.889 (8) A?, Z = 4, orthorhombic, space group Pbca, R = 0.059; 2, a = 10.494 (5) A?, b = 15.746 (8) A?, c = 19.659 (9) A?, β = 97.17 (4)°, Z = 2, monoclinic, space group P2₁/n, R = 0.081; 3, a = 15.089 (5) A?, b = 16.288 (5) A?, c = 17.249 (6) A?, Z = 4, orthorhombic, space group P2₁2₁2₁, R = 0.073.