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At least 19 recordsLinked to original sources
PubMed2004

Perturbation of conjugation in allylic lithium compounds due to stereochemical control of internal lithium coordination: crystallography, NMR, and calculational studies.

Several allylic lithium compounds have been prepared with ligands tethered at C(2). These are with (CH(3)OCH(2)CH(2))(2)NCH(2)-, 6, 1-TMS 5, 1,3-bis(TMS) 8, and 1,1,3-tris(TMS) 9. Allylic lithiums with (CH(3)OCH(2)CH(2))(2)NCH(2)C(CH(3))(2)-, are 10, 1-TMS 11, and 1,3-bis(TMS), 12 compounds with -C(CH(3))(2)CH(2)N-((S)-(2-methoxymethyl)-pyrrolidino) at C(2) 13, 1-TMS 14, and 1,3-bis(TMS) 15. In the solid state, 8-10 and 12 are monomers, 6 and 13 are Li-bridged dimers, and 5 and 7 are polymers. In solution (NMR data), 5, 7-12, 14, and 15 are monmeric, and 6 is a dimer. All samples show lithium to be closest to one of the terminal allyl carbons in the crystal structures and to exhibit one-bond (13)C-(7)Li or (13)C(1)-(7)Li spin coupling, for the former typically ca. 3 Hz and for the latter 6-8 Hz. In every structure, the C(1)-C(2) allyl bond is longer than the C(2)-C(3) bond, and both lie between those for solvated delocalized and unsolvated localized allylic lithium compounds, respectively, as is also the case for the terminal allyl (13)C NMR shifts. Lithium lies 40-70 degrees off the axis perpendicular to the allyl plane at C(1). These effects are variable, so the trend is that the differences between the C(1)-C(2) and C(2)-C(3) bond lengths, (13)delta(3)-(13)delta(1) values, and the (13)C(1)-(7)Li or (13)C-(6)Li coupling constants all increase with decreasing values of the torsional angle that C(1)-Li makes with respect to the allyl plane.

Journal Article↗
PubMed1979

Lithium compound treatment and psoriasis.

Observations were made of 12 cases of psoriasis that developed and three cases of psoriasis that became exacerbated during treatment with lithium compounds. Only two patients had a family history of psoriasis, and results of a search for increased frequencies of the histocompatibility antigens seen in psoriasis vulgaris were negative. The clinical features were identical to severe psoriasis vulgaris and the diagnosis was confirmed by histologic examination performed in six cases. However, the skin changes disappeared or returned to pretreatment level after withdrawal of lithium compounds. A positive provocation test result was obtained in two cases, the secondary latency time being shorter than the primary. We suggest that the psoriasis was induced or exacerbated by lithium compounds.

Adult↗
PubMed2002

A study on the structures of the substituted (aminomethyl)lithium and (thiomethyl)lithium compounds.

KEYWORDS: The structures of substituted (aminomethyl)lithium and (thiomethyl)lithium compounds have been examined. Geometric parameters, charge densities, bond orders, dipole moments and heats of formation for all the members of the two series of monomers and dimers of the units LiCN(R)2 and LiCSR where R=H, CH3(Me), C6H5(Ph) have been calculated. The structures of the three complex compounds containing the same units; [[Li(CH2SMe)(THF)]X], [Li2(CH2SPh)2(THF)4] and [Li2(CH2NPh2)2(THF)3] have also been modeled. Geometry optimizations have been performed with the semiempirical PM3 method. The molecular orbital calculations have been carried out by a self-consistent field method using the restricted Hartree-Fock formalism. Comparisons have been made with the corresponding properties of methyl lithium monomer and dimer. The results show that in all of the nitrogen-containing monomers, the C-Li bonds weaken and the Li-C-H(N) angles decrease due to the coordination of lithium with nitrogen. Substitution of hydrogen atoms by methyl or phenyl groups decreases the Li-N coordination. In the sulfur-containing compounds, sulfur behaves similarly to nitrogen but the changes are smaller because the 3p lone-pair orbital of sulfur is higher in energy than the 2p lone-pair of nitrogen. All the dimers of nitrogen/sulfur-containing methyl lithium derivatives form six-membered rings in which the Li-N(S) coordination is greater than the one in the corresponding monomers. Dimerization reactions have been found to be exothermic and the formation of all the dimers is favored. The results obtained for the three complex structures are comparable to the experimental results reported in the literature.

Amines↗
PubMed1995

Mutagenicity, carcinogenicity and teratogenicity of lithium compounds.

This paper reviews the information available concerning the mutagenic, teratogenic and carcinogenic effects of lithium. Such effects would be highly unlikely in an occupational setting but might be a risk to the considerable percentage of the population treated for manic-depressive disorders. It is concluded that lithium compounds have no significant clastogenic and, based on studies on microorganisms, only a doubtful mutagenic activity. Information on teratogenic effects is contradictory. While some observations in man and a few animal studies suggest that lithium in concentrations in the order of those given to patients may cause malformations, other observations do not support this claim and the risk with a carefully controlled therapy is probably small. Until more information becomes available from ongoing lithium data registries, it is probably prudent to exercise caution in treating pregnant women with lithium during the period of cardiac organogenesis. No information is available on cancer caused by treatment with lithium, and it is highly unlikely that lithium is carcinogenic.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

[Efficacy of the lithium compound with prolonged action during "reserpine depression"].

A single administration of the new lithium compound with prolonged action formed on the basis of lithium oxyburate produces an antiblepharoptosis effect in rats with reserpine depression for 24 to 48 h. It optimally prevents the development of "reserpine-desynchronization" in rats when prescribed in the morning at intervals of 48 h.

Animals↗
PubMed2006

Perturbation of conjugation in internally solvated allylic lithium compounds: variation of ligand structure. NMR and X-ray crystallography.

Several allyic lithium compounds were prepared with different potential ligands tethered at C2. These are with CH3OCH2CH2NCH3CH2-, 5 and 1-TMS 6, with (CH3)2NCH2CH2NCH3CH2-, 1-TMS 7, and with ((CH3)2NCH2CH2)2NCH2-, 8 and 1-TMS 9. In all these compounds Li is fully coordinated to the pendant ligand and is sited off the axis perpendicular to the allyl plane at one of the allyl termini as indicated by a combination of X-ray crystallography and NMR spectra. Compounds 5 and 8 are Li-bridged dimers as shown by X-ray crystallography and also dimeric in benzene solution as determined from freezing point determinations. Compounds 6, 7, and 9 are monomeric in THF-d8 or diethyl ether-d10 solution and exhibit one bond 13C1, 6Li scalar coupling at low temperature. Taken together the crystallographic and NMR data indicate that all of these compounds incorporate partially delocalized allylic moieties. Compounds 5 and 8 undergo fast 1,3-Li-sigmatropic shifts that are proposed to take place within low concentrations of monomers in fast equilibrium with prevalent dimers. Averaging with increasing temperature of the one-bond 13C, 6Li coupling constant in 6, 7, and 13 provided the dynamics of bimolecular C-Li exchange with Delta H++ values of 6.7, 12, and 13 kcal x mol(-1), respectively. Averaging of the diastereotopic N(CH3)2 13C resonances of 7 is indicative of fast transfer of coordinated ligand between faces of the allyl plane Delta H++ = 5.3 kcal x mol(-1) combined with slower inversion at nitrogen. Compound 8 exhibits similar effects. It is concluded that variation of the ligand structure changes dynamic behavior of the compounds but has little influence of their degrees of delocalization.

Journal Article↗
PubMed2004

NMR studies of structure and reorganization dynamics of an [6Li]-allylic lithium compound complexed to [14N,15N]-N,N,N',N'-tetramethylethylenediamine: inversion and ligand lithium exchange.

Proton, 13C, 6Li, and 15N NMR line-shape studies of exo,exo-1-trimethylsilyl-3-(dimethylethylsilyl)allyllithium-6Li complexed to [14N,15N]-N,N,N',N'-tetramethylethylenediamine (TMEDA) 2 as a function of temperature and of added diamine reveal the dynamics of three fast equilibrium reorganization processes. These are (with DeltaH values in kilocalories per mole and DeltaS values in entropic units): mutual exchange of lithium between two 2 molecules (6.3, -21), exchange of TMEDA between its free and complexed states (5.0 and -22), and first-order transfer of complexed ligand between the allyl faces (7.0 and -20). Intermediates that are dimeric in TMEDA are proposed for the first two of these reorganization processes.

Journal Article↗
PubMed2004

A DFT computational study on electrophilic substitutions upon alpha-oxy-substituted benzylorganolithium compounds: lithium catalysis is the hidden piece of the puzzle.

A detailed DFT (B3LYP/6-31+G*) study upon alpha-oxybenzylorganolithium compounds such as alpha-carbamoyloxybenzyllithium 1 has revealed two relevant issues concerning the outcome of electrophilic substitutions (1) lithium salts catalyze these reactions, and (2) some pi lithium complexes can provide an extra position to which electrophiles can anchor and thus drive invertive (at the carbanionic carbon) processes. Calculations have shown that carboxylation, alkylation, and acylation should take place with inversion at the original C-Li bond.

Journal Article↗
PubMedDate not supplied

Effects of acute oral administration of lithium compounds on multiple schedule performance in rats.

Adult male Sprague-Dawley rats were given acute oral administrations of lithium carbonate or lithium chloride at concentrations of 100, 200, and 300 mg/kg. Barpressing performance on a multiple fixed ratio 20/fixed interval 5 minute schedule was measured daily. The 200 and 300 mg/kg administrations of lithium chloride produced significant decreases in barpressing performance and all levels of lithium carbonate produced significant changes in performance. A 24 hour delay in the maximal behavioral effect of the 300 mg/kg dose of lithium carbonate paralleled previous findings showing delays in peak brain lithium levels after oral administration of lithium carbonate.

Administration, Oral↗
PubMed2001

A theoretical prediction of potentially observable lithium compounds with planar tetracoordinate carbons.

Several potentially experimentally accessible lithiated heterocyclic and heteroatom compounds with planar tetracoordinate carbons (ptC) have been predicted computationally. These utilize the strong electron-donating ability and the bridging proclivity of lithium to achieve the ptC preferences. As the p orbitals on the central carbons are only partially occupied, their electronic structures are similar to those of the related carbenes, e.g. imidazole-2-ylidene, rather than to the other ptC compounds such as dilithiocyclopropane.

Journal Article↗
PubMed2004

The role of intermolecular polarization for the stability of lithium intercalation compounds of alpha- and beta-perylene.

Lithium intercalation compounds of alpha- and beta-perylene are investigated by photoelectron spectroscopy. Spectroscopic data together with a Born-Haber cycle provide information on the formation enthalpy of those materials. This approach allows understanding the amount of charge transferred from the alkali metal atoms to the pi system, and illuminates the role of molecular versus solid-state properties in the formation of the intercalation compounds. In the bulk of alpha-perylene material, molecular dimerization survives upon intercalation which reduces the Madelung energy of the intercalation compound but increases the electron-accepting capability of the organic system and facilitates the ionization of lithium atoms in the molecular solid environment. The lower ionization potential results in a larger charge transfer (about two electrons per molecule) in alpha-perylene compared to the monomeric system, beta-perylene.

Journal Article↗
PubMed2006

Amino-functionalised diarylphosphide complexes of the alkali metals and lanthanum.

The secondary phosphines Ar(C6H4-2-CH2NMe2)PH [Ar = mes (3), Tripp (4)] may be isolated in good yields from reactions between Li(C6H4-2-CH2NMe2) and the respective dichlorophosphine, followed by reduction with LiAlH4 [mes = 2,4,6-Me3C6H2, Tripp = 2,4,6-Pri3C6H2]. Metalation of either 3 or 4 with BunLi gives the corresponding lithium compound; the lithium derivative of 3 was isolated as the separated ion pair complex [Li(12-crown-4)2][(mes)(C6H4-2-CH2NMe2)P].THF (5). The lithium complexes Ar(C6H4-2-CH2NMe2)PLi undergo metathesis reactions with either NaOBut or KOBut to give the heavier alkali metal phosphides {Ar(C6H4-2-CH2NMe2)P}M.1/2OEt2 [Ar = mes, M = Na (8), K (9); Ar = Tripp, M = K (10)]. Metathesis reactions between 9 and LaI3(THF)4 give only intractable products; in contrast, a metathesis reaction between 10 and LaI3(THF)4 yields the heteroleptic complex {(Tripp)(C6H4-2-CH2NMe2)P}2LaI (11). Compound 11 reacts cleanly with K{N(SiMe3)2} to give {(Tripp)(C6H4-2-CH2NMe2)P}2La{N(SiMe3)2} (14). Compounds 3-5, 8-11 and 14 have been characterised by multi-element NMR spectroscopy; in addition, compounds 5, 11 and 14 have been studied by X-ray crystallography.

Journal Article↗
PubMed2002

Structure and phase stability of binary zintl-phase compounds: lithium-group 13 intermetallics and metal-doped group 14 clathrate compounds.

The structure/bonding relationship in a series of intermetallic phases of Li with Al, Ga, and In was investigated by density functional theory and complemented by a model based on tight-binding theory and the method of moments. The combination of these two approaches provides a simple scheme which allows for both a comprehensive understanding of structural trends and the ability to predict low-energy structures for a given composition. This analysis gives a straightforward picture of phase stability in terms of local geometric features such as triangular, square, and hexagonal arrangements of atoms. The approach was extended to examine the structural properties of metal-doped clathrate compounds of C, Si, Ge, and Sn. Clathrate-type phases based on the frameworks Si172, Ge172, Si40, and Ge40 are not only likely to be energetically favorable but may also exhibit high thermoelectric efficiency.

Journal Article↗
PubMed2003

Bridgehead enolates: substitution and asymmetric desymmetrization of small bridged carbonyl compounds by lithium amide bases.

[reaction: see text] Contrary to expectations, a number of bridged carbonyl compounds undergo facile bridgehead metalation with lithium amide bases. Diketone, lactone, lactam, and imide functions are all demonstrated to participate in this type of "bridgehead enolate" chemistry, leading to a range of substituted products. Meso compounds can also be desymmetrized in very high ee by asymmetric bridgehead metalation.

Journal Article↗