Utility of Arylamido Ligands in Yttrium and Lanthanide Chemistry1

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Abstract
The reactivity of KNHAr reagents (Ar = C6H5, C6H3Me2-2,6, C6H3iPr2-2,6) with lanthanide and yttrium trichlorides has been investigated. With the larger metals Nd and Sm and the smaller 2,6-dimethyl-substituted ligand, the bimetallic dianionic complexes [K(THF)6]2[Ln(μ-NHC6H3Me2-2,6)(NHC6H3Me2-2,6)3]2 (Ln: Sm, 1a; Nd, 1b) are isolated as the potassium salts. Under the same reaction conditions YCl3 forms a bimetallic anion which retains chloride: [K(DME)2(THF)3][Y2(μ-NHC6H3Me2-2,6)2(μ-Cl)(NHC6H3Me2-2,6)4(THF)2], 2. With the larger 2,6-diisopropyl ligands, neutral complexes are isolated in both solvated monometallic and unsolvated bimetallic forms. With Nd, a distorted octahedral trisolvate, Nd(NHC6H3iPr2-2,6)3(THF)3, 3, was obtained, whereas with Yb and Y the trigonal bipyramidal disolvates, Ln(NHC6H3iPr2-2,6)3(THF)2 (Ln: Yb, 4a; Y, 4b), were isolated. THF-free complexes of the NHC6H3iPr2-2,6 ligand are available by reacting the amine NH2C6H3iPr2-2,6 with Ln[N(SiMe3)2]3 complexes. By this route, the dimers [Ln(μ-NHC6H3iPr2-2,6)(NHC6H3iPr2-2,6)2]2 (Ln: Yb, 5a; Y, 5b) were isolated. The reaction of the unsubstituted arylamido salt KNHC6H5 with NdCl3 produced an insoluble material which was characterized as [Nd(NHC6H5)3(KCl)3], 6. 6 reacted with Al2Me6 in hexanes and produced a heteroleptic mixed-metal complex {[Me2Al(μ-Me2)]2Nd(μ3-NC6H5)(μ-Me)AlMe}2, 7, and the trimeric aluminum arylamido complex [Me2Al(μ-NHC6H5)]3, 8. The solvent of crystallization and relevant crystallographic data for the compounds identified by X-ray analysis follow: 1a, THF, 156 K, P21/n, a = 12.985(2) Å, b = 27.122(5) Å, c = 17.935(3) Å, β = 100.19(1)°, V = 6216(1) Å3, Z = 2, 6148 reflections (I > 3σ(I)), RF = 7.1%; 1b, THF, 156 K, P21/n, a = 12.998(2) Å, b = 27.058(3) Å, c = 17.962(2) Å, β = 99.74(1)°, V = 6225(1) Å3, Z = 2; 2, DME/hexanes, P21/n, a = 23.335(2) Å, b = 12.649(1) Å, c = 27.175(3) Å, β = 96.36(1)°, V = 7971(1) Å3, Z = 4, 2788 reflections (I > 3σ(I)), RF = 9.5%; 3, THF, P21, a = 12.898(1) Å, b = 16.945(1) Å, c = 13.290(1) Å, β = 118.64(2)°, V = 2549.3(3) Å3, Z = 2, 3414 reflections (I > 3σ(I)), RF = 4.3%; 4a, hexanes, P21, a = 9.718(2) Å, b = 19.119(3) Å, c = 12.640(2) Å, β = 112.08(1)°, V = 2176.3(6) Å3, Z = 2, 2933 reflections (I > 3σ(I)), RF = 4.3%; 4b, hexanes, 158 K, a = 9.729(2) Å, b = 19.095(5) Å, c = 12.744(1) Å, β = 112.11(1)°, V = 2193.4(6) Å3; 5b, hot toluene, 158 K, P21, a = 19.218(9) Å, b = 9.375(3) Å, c = 19.820(5) Å, β = 110.25(2)°, V = 3350(2)Å3, Z = 2, 1718 reflections (I > 2σ (I)), R1 = 9.7%; 7, hexanes, 156 K, P1̄, a = 9.618(3) Å, b = 12.738(4) Å, c = 9.608(3) Å, α = 99.32(1)°, β = 108.87(1)°, γ = 94.23(1)°, V = 1089.1(6) Å3, Z = 2, 2976 reflections (I > 3σ(I)), RF = 3.9%; 8, hexanes, 156 K, Pcab, a = 23.510(5) Å, b = 25.462(5) Å, c = 8.668(2) Å, V = 5188(1) Å3, Z = 8, 1386 reflections (I > 3σ(I)), RF = 5.7%.

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