SYNTHESIS AND STRUCTURE OF LANTHANIDE COMPLEXES DERIVED FROM THE O,N-CHELATING, BIS(METHYLPYRIDINE)-SUBSTITUTED ALCOHOL HOC(CME(3))(2-CH(2)NC(5)H(3)ME-6)(2)

Hydrolysis of the product formed by reacting 2 equiv of 2-(lithiomethy lene)-6-methylpyridine with trimethylacetyl chloride gives the alcohol HOC(CMe(3))(2-CH(2)NC(5)H(3)ME-6)(2), 1 (HOR), in 44% yield. Three eq uivalents of 1 reacts with Yb[N(SiMe(3))(2)](3) to form Yb(OR)(3), 2a. The analogous 2 equiv reaction generates Yb(OR)(2)[N(SiMe(3))(2)], 3. X-ray diffraction studies were successful on 3 and on 2b, the Sm anal og of 2a. Two of the alkoxide ligands in Sm(OR)(3), 2b, are bidentate such that each has an uncomplexed nitrogen donor atom oriented away fr om the metal. These chelates occupy basal positions in the distorted s quare pyramidal geometry around the metal center in 2b such that the o xygen donors are trans. The axial position is occupied by the third al koxide which is monodentate through its oxygen donor atom. This leaves a total of four unattached pyridine functionalities available for fur ther coordination. The ligand arrangement in 3 is very similiar to tha t in 2b except that the monodentate alkoxide in 2b is replaced by a N( SiMe(3))(2) group. A ligand fragmentation product, (R'O)(2)Sm(mu-OR)(2 )Na, 4, containing the chelating bidentate pyridine enolate ligand [OC (CMe(3))(=2-CHNC(5)H(3)Me-6)] (OR'), formed by loss of a 2,6-dimethylp yridine group from OR, was also isolated in the course of these studie s. Each OR ligand in 4 has its oxygen atom bridging Sm and Na, one pyr idine nitrogen coordinated to Na, and one pyridine nitrogen which is n ot connected to any metal. The samarium center in 4 has a distorted oc tahedral geometry generated by two chelating R'O groups and the two br idging oxygens from the OR groups. The nitrogen donor atoms of the R'O groups have a cis orientation and are trans to the bridging ligands. The sodium atom has a distorted tetrahedral geometry. 2b crystallizes from toluene in space group P2(1) with a = 11.5464(7) Angstrom, b = 10 .7865(5) Angstrom, c = 22.5041(9) Angstrom, beta = 98.930(4)degrees, V = 2768.8(2) Angstrom(3), and Z = 2. Least squares refinement of the m odel based on 5804 reflections (\F-0\ > 4.0 sigma(\F-0\)) converged to a final R(F) = 2.7%. 3 crystallizes from hexane in space group P (1) over bar with a = 11.109(2) Angstrom, b = 15.135(3) Angstrom, c = 16.1 97(3) Angstrom, alpha = 96.482(12)degrees, beta = 106.952(10)degrees, gamma = 110.838(10)degrees, V = 2362.0(8) Angstrom(3), and Z = 2. Leas t squares refinement of the model based on 5596 reflections (\F-0\ > 3 .0 sigma(\F-0\)) converged to a final R(F) = 3.8%. 4 crystallizes from hexane in space group P2(1)/n with a = 15.229(4) Angstrom, b = 24.826 (4) Angstrom, c = 15.662(3) Angstrom, beta = 97.70(2)degrees, V = 5868 (2) Angstrom(3), and Z = 4. Least squares refinement of the model base d on 6124 reflections (\F-0\ > 3.0 sigma(\F-0\)) converged to a final R(F) = 5.5%.