Utility of Arylamido Ligands in Yttrium and Lanthanide Chemistry(1)

The reactivity of KNHAr reagents (Ar = C(6)H(5), C(6)H(3)Me(2)-2,6, C(6)H(3)(i)Pr(2)-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(&mgr;-NHC(6)H(3)Me(2)-2,6)(NHC(6)H(3)Me(2)-2,6)(3)](2) (Ln: Sm, 1a; Nd, 1b) are isolated as the potassium salts. Under the same reaction conditions YCl(3) forms a bimetallic anion which retains chloride: [K(DME)(2)(THF)(3)][Y(2)(&mgr;-NHC(6)H(3)Me(2)-2,6)(2)(&mgr;-Cl)(NHC(6)H(3)Me(2)-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(NHC(6)H(3)(i)Pr(2)-2,6)(3)(THF)(3), 3, was obtained, whereas with Yb and Y the trigonal bipyramidal disolvates, Ln(NHC(6)H(3)(i)Pr(2)-2,6)(3)(THF)(2) (Ln: Yb, 4a; Y, 4b), were isolated. THF-free complexes of the NHC(6)H(3)(i)Pr(2)-2,6 ligand are available by reacting the amine NH(2)C(6)H(3)(i)Pr(2)-2,6 with Ln[N(SiMe(3))(2)](3) complexes. By this route, the dimers [Ln(&mgr;-NHC(6)H(3)(i)Pr(2)-2,6)(NHC(6)H(3)(i)Pr(2)-2,6)(2)](2) (Ln: Yb, 5a; Y, 5b) were isolated. The reaction of the unsubstituted arylamido salt KNHC(6)H(5) with NdCl(3) produced an insoluble material which was characterized as [Nd(NHC(6)H(5))(3)(KCl)(3)], 6. 6 reacted with Al(2)Me(6) in hexanes and produced a heteroleptic mixed-metal complex {[Me(2)Al(&mgr;-Me(2))](2)Nd(&mgr;(3)-NC(6)H(5))(&mgr;-Me)AlMe}(2), 7, and the trimeric aluminum arylamido complex [Me(2)Al(&mgr;-NHC(6)H(5))](3), 8. The solvent of crystallization and relevant crystallographic data for the compounds identified by X-ray analysis follow: 1a,THF, 156 K, P2(1)/n, a = 12.985(2) Å, b = 27.122(5) Å, c = 17.935(3) Å, beta = 100.19(1) degrees, V = 6216(1) Å(3), Z = 2, 6148 reflections (I > 3sigma(I)), R(F)() = 7.1%; 1b,THF, 156 K, P2(1)/n, a = 12.998(2) Å, b = 27.058(3) Å, c = 17.962(2) Å, beta = 99.74(1) degrees, V = 6225(1) Å(3), Z = 2; 2,DME/hexanes, P2(1)/n, a = 23.335(2) Å, b = 12.649(1) Å, c = 27.175(3) Å, beta = 96.36(1) degrees, V = 7971(1) Å(3), Z = 4, 2788 reflections (I > 3sigma(I)), R(F)() = 9.5%; 3, THF, P2(1), a = 12.898(1) Å, b = 16.945(1) Å, c = 13.290(1) Å, beta = 118.64(2) degrees, V = 2549.3(3) Å(3), Z = 2, 3414 reflections (I > 3sigma(I)), R(F)() = 4.3%; 4a, hexanes, P2(1), a = 9.718(2) Å, b = 19.119(3) Å, c = 12.640(2) Å, beta = 112.08(1) degrees, V = 2176.3(6) Å(3), Z = 2, 2933 reflections (I > 3sigma(I)), R(F)() = 4.3%; 4b, hexanes, 158 K, a = 9.729(2) Å, b = 19.095(5) Å, c = 12.744(1) Å, beta = 112.11(1) degrees, V = 2193.4(6) Å(3); 5b, hot toluene, 158 K, P2(1), a =19.218(9) Å, b = 9.375(3) Å, c = 19.820(5) Å, beta = 110.25(2) degrees, V = 3350(2)Å(3), Z = 2, 1718 reflections (I > 2sigma (I)), R1 = 9.7%; 7, hexanes, 156 K, P&onemacr;, a = 9.618(3) Å, b = 12.738(4) Å, c = 9.608(3) Å, alpha = 99.32(1) degrees, beta = 108.87(1) degrees, gamma = 94.23(1) degrees, V = 1089.1(6) Å(3), Z = 2, 2976 reflections (I > 3sigma(I)), R(F)() = 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) Å(3), Z = 8, 1386 reflections (I > 3sigma(I)), R(F)() = 5.7%.