3717
Znorg. Chem. 1984, 23, 3717-3720
Contribution from the Departments of Chemistry and Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, and IBM San Jose Research Laboratory, IBM Corporation, San Jose, California 95193
Synthesis of Isotopic Forms of Dilithiomethane [(CH26Li2),and (CD2Li2),]and Preliminary Structural Information Obtained by X-ray Powder and Solid-Phase 13C N M R Techniques JOHN A. GURAK: JOHN W. CHINN, JR.? RICHARD J. LAGOW,*+HUGO STEINFINK,*$ and COSTANTINO S.YANNONI*l Received March 20, 1984
New synthetic methods have been developed to alter the Ziegler procedure' for synthesis of dilithiomethane of various isotopic compositions. [CH2(6Li2)],has been prepared to facilitate solid I3C NMR spectra. (CD2Li2),has been prepared, and preliminary X-ray powder pattern data are reported. The first solid-state 13CNMR spectrum on any organolithium compound has been obtained. The I3C NMR spectra of solid samples of [CH3(6Li)]4and [CH2(6Liz)],are discussed.
Introduction There is unusual interest in the structures of polylithium compounds such as dilithi~methane?-~Although it may soon be possible to grow crystals of dilithiomethane, its limited solubility has made this initially very difficult. Also, it is possible to observe 'Li resonance in certain solvents for dilithiomethane. At the present time no satisfactory solvents have been found such that natural-abundance 13Cspectra are possible for unsubstituted polylithium compounds. Quite interestingly the experimental conditions for the synthesis of isotopically substituted dilithiomethane differ substantially in reaction conditions from those that we have reported for substituted-hydrogen and substituted-lithium-7 dilithi~methane:~ dilithiomethane
-+ 223-226 ' C
(CH3*Li)4 (CH2*Li2), 95-96%
(C2*Li2), 1-2%
*Li = 7Li or
+ (C3*Li4), + (CH3*Li)4 0.5-1%
2-3%
isotope
dilithiomethane-d2
(CD2Li2), 95-96571
+ (C2Li2), + (C3Li4)"+ (CD3Li)4 1-2%
