J . A m . Chem. SOC.1988, 110, 5924-5925
5924
Uranium Alkoxide Chemistry. 1. Synthesis and the Novel Dimeric Structure of the First Homoleptic Uranium(II1) Aryloxide Complex W. G. Van Der Sluys,la C. J. Burns,la J. C. Huffman,Ib and A. P. Sattelberger*qia
C6
Inorganic and Structural Chemistry Group (INC-4) Isotope and Nuclear Chemistry Division Los Alamos National Laboratory Los Alamos New Mexico 87545 The Molecular Structure Center, Department of Chemistry Indiana University, Bloomington Indiana 47405 Received March 18. 1988 A number of homoleptic uranium alkoxide complexes have been reported, and the structurally characterized examples include [U( 0-2,6-Pri2C6H3) 5]-, [U2(OBu')J, U2( OBU')~, U2(OPr') o, and U(OMe)6.2-7 Conspicuous in their absence are any examples of homoleptic uranium(II1) alkoxide complexes.* These would be valuable starting materials for further investigations of nonaqueous uranium( 111) chemistry and for uranium alkoxide cluster syntheses via comproportionation reactions with higher oxidation state uranium alkoxides2s3and oxo-alkoxide~.~In addition, there is also a possibility that alkoxide-ligated uranium(II1) centers might be coaxed into homodinuclear relationship^.^^ Here we describe the successful syntheses of two uranium( 111) aryloxide complexes. Addition of 3.1 equiv of HO-2,6-R2C6H3(R = But or Pr') to concentrated hexane solutions of U[N(SiMe3)2]310 at room temperature causes a rapid color change from bright red to dark brown and precipitation of a dark green (R = But, 1) or dark purple (R = Pr', 2) solid. After 4 h, the U(O-2,6-R2C6H3)3complexes are isolated (50% yield) by filtration, washed with cold hexane, and dried in vacuo (eq 1). Both compounds are ether- and hydrocarbon-soluble and very air-sensitive." The ' H N M R spectra of 1 and 2, recorded at 25 OC in benzene-d6, show only one type of phenoxide R group.12
+
c&14
U[N(SiMe3)2]3 3HO-2,6-R2C6H, U(O-2,6-R2C6H3), + 3HN(SiMe3)2 (1) 1, R = But 2, R = Pr' Single crystals of 2 were grown from a concentrated hexane solution at -40 OC, and the structure was determined from X-ray diffraction data collected at -1 55 OC.I3 In the solid state, 2 adopts (1) (a) Los Alamos National Laboratory. (b) Indiana University. (2) Bradley, D. C.; Mehrotra, R. C.; Gaur, D. P. Metal Alkoxides; Academic Press: London, 1978. (3) Mehrotra, R. C.; Kapoor, P. N.; Batwara, J; M. Coord. Chem. ReE. 1980, 31, 67. (4) Blake, P. C.; Lappert, M. F.; Taylor, R. G.; Atwocd, J. L.; Zhang, H. Inorg. Chim. Acta 1987, 139, 13. (5) (a) Cotton, F. A,; Marler, D. 0.;Schwotzer, W. Inorg. Chem. 1984, 23, 421 I . (b) Cotton. F. A,; Marler, D. 0.;Schwotzer, W. Inorg. Chim. Acta 1984, 85, L3 1. (6) Bursten, B. E.; Casaria, M.; Ellis, D. E.; Fragala, 1.; Marks, T. J. Inorg. Chem. 1986, 25, 1257 and references therein. (7) Van Der Sluys, W. G.; Sattelberger, A. P., in preparation (a review of lanthanide and actinide alkoxide chemistry). (8) Zozulin, A. J.; Moody, D. C.; Ryan, R. R. Inorg. Chem. 1982, 21, 3083. This paper describes an unsuccessful attempt to prepare U(OC,H,),. (9) New uranium(V1) oxo-alkoxide complexes, U0,(OCMe3)2(0PPh,)2 and U02(0CMe3)2[0U(OCMe3),12, have been synthesized and structurally characterized at Los Alamos. Burns, C. J.; Sattelberger, A. P., submitted for publication. (10) Andersen, R. A. Inorg. Chem. 1979, 18, 1507. ( 1 1 ) Anal. Calcd (Found) for U03C42H63:C, 59.06 (58.43); H, 7.45 (7.48); N , 0.00 (
