The Use of Heterometallic Bridging Moieties To Generate Tractable Lanthanide Complexes of Small Ligands

COMMUNICATIONS P. L. Pauson. Z>rruhi,dron 1985. 41. 5855-5860, N. E. Schore. Org. ReucI. S. Shamhayati, W. E. C r o w . S. L. Schreiber, Tetrahedron L ~ I I 1990.3t. 5292. M. Thorninen, P. Gerber. R. Keese. Chbnia 1991. 45, 21 -24: N. Jeong, Y. K. Chung. B. Y Lee, S. H. Lee. S:E. Yoo, Sjnkerl 1991. 204-206: M. E. Kraflt. I . L. Scott, R. H. Romero. S. Feibelmann, C. E. Van Pelt, J. A m . Chrm. S i x . 1993. 115. 7199 7207. A. 7. Balabaii. M. Banciu, V. Ciorha, Annulenrs, Bunzo-, Helero-, Homo- D c r i w r i w s und rhrir fiilenre lsonwr. 3 u ( F ) were considered independent: R = 0.125, R, = 0.120. 9: Monoclinic, P2,!n, ( I = 685.X(2). h = 1796 7(4). c = 662.1(1) pm. [i = 90.08(2); 2090 measured re- llections. of which 1080 with F > 3 u ( F ) were considered Independent: R = 0.055. R , = 0.041. Further details of the crystal structure investigations ma) be obtained from the Fachinformationszentrum Karlsruhe, D-76344 Eg- genstein-Leopoldshafen ( F R G ) on quoting the depository numbers CSD- 400696 (8) and CSD-400697 (9). H. Irngartinger. K. L. Lukas. Angrw. Chrm. 1979. 91,750: Angriv. Chrm. Inr. Ed. D i R I . 1979. 18. 694-695: M. N. Paddon-Row, K. N. Houk, P. Dowd, P. Gamer, R Schappert, Erruhedron Lclf. 1981. 22, 4799 -4812; M. Eisenstein, F. L . Hirshfeld. Aclu CruluNogr. S K ~ . B 1983, 39. 61 -75: P. G. Gassman. M. 1.. Greenlee. D. A. Dixon, S. Richtsmeier. J. 2. Gougoutas, J Am. Chrm. sot,. 1983. ~ ( J J 5865-5874. R. Hoffrnaiin. fitrukrdron Lrrf. 1970. 2907-2909; H. Gunther. ihid. 1970, H . Irngarringer. W. Reimann. R. Lang, M. Christl, .4cru Cry3/a//ogr. Sect. B 1990. 46. 234-238. and references therein. T. J. Kati. E. J. Wang, N. Acton, J. Am. Chrm. Soc. 1971. 93, 3782-3783; T. J. Kati. R. J. Roth. N. Acton. E J. Carnahan. Org. S y l h . 1973, 53, 157. For many years it has been known that trialkylaluminum complexes will add to lanthanide complexes containing bulky stabilizing co-ligands to form bridged heterometallic species such as those given in Scheme 1 . Recently, we have shown that AIMe, will also bridge and stabilize metal ligand combinations such as Y(OCMe,), in [ y { ( p - OCMe,)(p-Me)A1Me,},][91 and [(C5H,SiMe,)Y(OCMe3),1 in [(C5H,SiMe,)Y{(p-OCMe,)(p-Me)A1Me,),l .[' I We now report that AIMe, will not only react with soluble reagents containing bulky ligands, but that it will also react with and solubilize the insoluble materials formed from reactions of lanthanide halides with small anionic hgands. The reaction of anhydrous NdCI, with three equivalents of LiNMe, (Z = NMe,) in THF at room temperature formed a blue material which was identified as 1 a [Eq. (a)]. Reaction of AIMe, or GaMe, with a suspension of 1 a in hexane yielded the hexane- soluble products 2a (violet-blue) and 2 b (blue), respectively. NdCI, + 3 LiNMe, la The Use of Heterometallic Bridging Moieties To Generate Tractable Lanthanide Complexes of Small Ligands ** William J. Evans,* Reiner Anwander, Robert J. Doedens, and Joseph W. Ziller Dedicated to Professor M . Frederick Hawthorne on the occasion of his 65th birrhduy Lanthanide chemistry is dominated by large, anionic ligands which meet the steric and electronic demands of these large electropositive metals. On the other hand, the chemistry of simple lanthanide complexes of general formula LnZ, in which Z is a small anionic ligand such as methanide, methanolate, ethanolate. or dimethylamido. is poorly developed since these complexes are either unstable or insoluble.[',21 The only ho- moleptic lanthanide complexes with small ligands which are tractable enough to be definitively characterized by X-ray crys- tallography are the hexamethyl ate complexes [LnMe,13- of the late lanthanides Ho, Er, and L u . [ ~ ] We describe here a method for the synthesis of isolable, sol- uble lanthanide complexes of small ligands Z (Z = NMe,, Me) which also provides a convenient route to heterometallic com- plexes which have component combinations of interest with respect to polymerization and the formation of ma- terials from molecular precursors.[41 We also report details of the first structurally characterized molecular complexes con- taining a lanthanide metal and gallium.[51 [*I Prof W. J. Evans, Dr. R. Anwander. Prof. R. J. Doedens, Dr. J. W. Ziller Department of Chemistry, University of California Irwne. CA 92717 (USA) Telef:,ix. Int. code [**I We thank the Division of Chemical Sciences of the Office of Basic Energy Sciences of the Department of Energy for support for this research and the Deutsche Forschungsgemeinschaft for a Postdoctoral Fellowship (to R. A.j. Angeii,. Chmi. i n / . Ed. EngI. 1994. 33. No. 15/16 3 MMe, [Nd(NMe,),(LiCI),] [Nd(NMe,),(MMe,),] 2a, M Al; 2 b , M + 3 LiCl (a) Ga The intensely colored solutions of 2 are stable at room temper- ature. Evaporation of the solvent results in oily residues which solidify at - 35 C. These solids slowly decompose at room tem- perature to form large colorless crystals of [{ Me,NMMe,} 2] (M = Al, Ga (4))[ ] which sublime to the top of the container. Compounds 2 a and 2 b can be isolated in 80 % yield by crystal- lization of the initially isolated solids from hexane at - 35 C; the molecular structure of 2 b is shown in Figure 1 .[' 21 Qc2 Fig. 1. Molecular structure o f 2 b ; the numbering isidentical to that ofisostructural 2a. Thermal ellipsoids are drawn at the 50% probability level. Selected distances [.I Ndl-N1- M1 94.7(2) [96.0(1)], Ndt-Ct-M1 84.3(2) (85.7(1)], Nl-Ndl-C1 77.3(2) [74.7(1)], Nl-MI-CI 103.0(3) [102.5(2)], Ndl-N2-M2 94.5(4) [92.6(3)]. mc, VCH Verlugs~~,.sellschufl mhH, 0-69451 Weinheim, 1994 0570-0R33/94if51j-l64f $ iO.OO+ .2.i!O