Synthesis, Properties, and X-ray Structures of the Lanthanide .eta.6-Arene-Bridged Aryloxide Dimers Ln2(O-2,6-i-Pr2C6H3)6 and Their Lewis Base Adducts Ln(O-2,6-i-Pr2C6H3)3(THF)2 (Ln = Pr, Nd, Sm, Gd, Er, Yb, Lu) (original) (raw)

1994, Inorganic Chemistry

Reaction of 3 equiv of 2,6-diisopropylphenol with Ln[N(SiMe,)z]s (Ln = Nd, Sm, Er) in refluxing toluene and subsequent crystallization yield pale blue (Nd), deep yellow (Sm), or light pink (Er) crystals of the tris complexes Lnz(0-2,6-i-PrzCsH3)6 (Ln = Nd (l), Sm (2), Er (3)) in good yield. X-ray crystallographic studies of 1 and 2 reveal centrosymmetric, dimeric units bridged by −r−areneinteractionsofauniquearyloxideligand.Ln−Obondlengthsaverage2.122(9)(1,Nd)and2.101(6)A(2,Sm)forterminalligandsand2.21168)(1)and2.198(5)A(2)forbridgingaryloxideligands.-r-arene interactions of a unique aryloxide ligand. Ln-O bond lengths average 2.122(9) (1, Nd) and 2.101(6) A (2, Sm) for terminal ligands and 2.21168) (1) and 2.198(5) A (2) for bridging aryloxide ligands. −r−areneinteractionsofauniquearyloxideligand.Ln−Obondlengthsaverage2.122(9)(1,Nd)and2.101(6)A(2,Sm)forterminalligandsand2.21168)(1)and2.198(5)A(2)forbridgingaryloxideligands.-Arene bridges hold the dimeric units together with an average Ln-C distance of 3.035 A for 1 and 2.986 and 3.016 A for the two independent molecules in the asymmetric unit of 2. Compounds 1-3 react with T H F in toluene solution to give the T H F bisadducts Ln(O-2,6-i-P&6H3)3(THF)2 (Ln = Nd (4), Sm (5), Er (6)) in essentially quantitative yield. In a related fashion, LU(O-~,~-~-P~~C~H~)~(THF) (7) was prepared following the reaction of Lu[N(SiMe3)2]3 with 3 equiv of diisopropylphenol in the presence of THF. The anhydrous trichlorides of Sm, Pr, Gd, and Yb react with 3 equiv of potassium 2,6-diisopropylphenoxide in T H F solution to give the 5-coordinate T H F bisadducts L~(O-~,~-~-~ZC~H~)~(THF)Z (Ln = Sm (5), Pr (8), Gd (9), Yb (10)). X-ray crystal structures have been obtained for LII(O-~,~-~-P~ZC~H~)~(THF)~ (Ln = Er (a), Lu (7), Pr (8), Gd (9)). The four compounds are isostructural, and the molecular structure consists of a distorted trigonal bipyramidal lanthanide metal center with two axialTHF and threeequatorial aryloxide ligands. Ln-O distances for the aryloxide ligands average 2.078 (6, Er), 2.044 (7, Lu), 2.172 (8, Pr), and 2.130 (9, Gd) while Ln-O distances for the T H F ligands average 2.346 (6), 2.296 (7), 2.482 (8), and 2.394 A (9). Solution IH and 13C N M R data, together with solution IR data, strongly support the proposal that the r-arene-bridged dimeric structures of 1-3 are maintained in both benzene and toluene solutions at room temperature. Crystal data for 1 (at -162 "C): monoclinic space group B 1 / a , a = 9.536(2) A, b = 21.219(6) A, c = 17.162(5) A, 0 = 104.43(1)", V = 3363.0 A3, Z = 2, dale = 1.335 g ~m -~, R(F) = 0.0518, R,(F) = 0.0522. Crystal data for 2 (at -70 "C): monoclinic space group n l / c , a = 9.555(2) A, b = 21.301(2) A, c = 33.220(4) A, /3 = 91.50(3)", V = 6759 A3, Z = 2 (2 molecules per asymmetric unit), dale = 1.341 g cm-3, R(F) = 0.0447, R,(F) = 0.0640. Crystal data for 6 (at -170 OC): monoclinic space groupP21, a = 9.693(1) A, b = 19.141(3) A, c = 12.083(1) A, /3 = 109.48(1)", V = 2113.50 A3, dale = 1.325 g ~m -~, Z = 2, R(F) = 0.047, R,(F) = 0.063. Crystal data for 7 (at -70 "C): monoclinic space group nl, a = 9.632( 1) A, b = 19.269(2) A, c = 12.164(1) A, /3 = 109.52(1)", V = 2127.9 A3, dale = 1.328 g cm-3, Z = 2, R(F) = 0.021, R,(F) = 0.031. Crystal data for 8 (at -70 "C): monoclinic space group P21, a = 9.857(2) A, b = 19.408(4) A, c = 12.085(3)&/3= 109.81(2)", V=2175.1A3,dcalc= 1.247g~m-~,Z=2,R(F)=O.O45,R,(F) =0.061. Crystal data for 9 (at -70 "C): monoclinic space group El, a = 9.755(1) A, b = 19.377(2) A, c = 12.184(1) A, /3 = 109.65(1)", V = 2168.1 A3, dalc = 1.276 g ~m -~, Z = 2, R(F) = 0.054, R,(F) = 0.073. Abstract published in Advance ACS Abstracts, July 1, 1994. (1) (a) CST-3. Present addreas: Department of Chemistry, University of Washington, BG-IO, Seattle, WA 98185. (b) CST-3, Mail Stop G739. (c) CST-3, Mail Stop C346. (d) Molecular Structure Center, Indiana University. (e) NMT-6, Mail Stop E510. (2) Bradley, D. C.; Cbudzynska, H.; Hursthouse, M. B.; Motevalli, M. ( 5 ) Coan, P. S.; McGcary, M. J.; Lobkovsky, E. B.; Caulton, K. G. Inorg. (6) McGeary, M. J.; Coan, P. S.; Folting, K.; Streib, W. E.; Caulton, K. (7) Evans, %' . J.; Deming,'T. J.; Olofson, J. M.; Ziller, J. W. Inorg. Chem. 1989. 28. 4027. (8) Ponffilet,'O.; Hubert-Pfalzgraf, L. G. Polyhedron 1989, 8, 2183.