TMEDA Molecule Research Articles

Synthesis, crystal structure, thermal studies, and antimicrobial activity of benzene-1,4-dicarboxylate-copper(II) based coordination polymer incorporating N,N,N′,N′-tetramethylethylenediamine

The synthesis, crystal structure and properties of [Cu(tmeda)(bdc)(H2O)2] n (1), where bdc2- (C8H4O4 2-) is the benzene-1,4-dicarboxylate dianion and tmeda is N,N,N′,N′-tetramethylethylenediamine, are reported. The metal ion in 1 is coordinated by a chelating tmeda molecule, two monodentate bdc2- ions and two water molecules to generate a tetragonally-elongated cis-CuN2O4 octahedron. Each bdc2- ion bridges two adjacent Cu(II) ions to generate zigzag polymeric chains and the packing is consolidated by O − H···O hydrogen bonds. Spectroscopic and thermal studies of 1 are consistent with the crystal structure. Complex 1 shows excellent activity against four bacterial strains, Bacillus spizizenii, Escherichia coli, Klebsiella pneumonia and Staphylococcus aureus.

An X-ray diffraction study of oriented lithium-N,N,N′,N′-tetramethyl-ethane-1,2-diamine intercalated graphite

The intercalation of N,N,N′,N′-tetramethyl-ethane-1,2-diamine (tmeda) into C6Li derived from papyex, a partially oriented graphite foil, results in the co-presence of two ternary phases having out-of-plane (c-axis) identity periods of 11.5 and 9.1Å. As we reported for the powdered sample prepared using a natural graphite source, these distances are associated with two tmeda orientations. The tmeda orientation had no significant effect on the in-plane lattice. The orientated texture of the sample gave in-plane (a-b plane) unit cell dimension, a=4.3Å, close to the √3ao distance of the stage I C6Li precursor unit cell and allowed changes in the in-plane packing to be detected by extending the reflux time of the reaction between C6Li and tmeda or by using the stage II binary C12Li as the precursor. An expansion of the in-plane lattice spacing to 4.6Å occurred for part of the sample. The ideal stoichiometry of the unexpanded ternary compound based on the unit cell volume and having the maximum number of tmeda molecules within the P6/mmm unit cell was estimated to be C6Li (tmeda)1. However, a structure factor analysis indicated that tmeda occupancy within the unit cell is fractional.

Preparations of Metal Trichalcogenophosphonates from Organophosphonate Esters

A new method for the preparation of metal trichalcogenophosphonates is presented wherein organophosphonate esters are first reduced with LiAlH(4) and subsequently treated with an organometallic reagent and elemental sulfur or selenium to give the desired trichalcogenophosphonate complex. Using this synthetic protocol with (n)BuLi as the organometallic reagent, the lithium trithiophosphonate complexes [Li(2)(S(3)PCH(2)Ph)(THF)(TMEDA)](2) (1) and [Li(4)(S(3)P(n)Pr)(2)(TMEDA)(3)](∞) (3), where THF = tetrahydrofuran and TMEDA = N,N,N',N'-tetramethylethylenediamine, have been prepared. In both cases, the formation of byproducts is also evident, including, for 1, the tetrathiohypodiphosphonate complex [(PhCH(2)P(S(2)))(2)Li(2)(THF)(4)] (2), which has been structurally characterized. Replacement of (n)BuLi with (n)Bu(2)Mg as the metallating agent led to much cleaner products and improved yields, with the new trithio- and triselenoorganophosphonate complexes [Mg(S(3)PCH(2)Ph)(TMEDA)](2) (4) and [Mg(Se(3)P(n)Pr)(TMEDA)](2) (5) reported. All trichalcogenophosphonate complexes have been structurally characterized in the solid state: 1 adopts a dimer structure in which the [PhCH(2)PS(3)](2-) ligand exhibits a unique μ(3)-η(2),η(2),η(2)-coordination mode; 3 is polymeric comprising of [Li(4)(S(3)P(n)Pr)(2)(TMEDA)(2)] dimers linked via additional bridging bis(monodentate) TMEDA molecules; 4 and 5 both adopt dimeric motifs with μ(2)-η(2),η(2) coordination of the magnesium centers.

The Intercalation of N,N,N′,N′-Tetramethyl-ethane-1,2-diamine (tmeda) into C6Li and C12Li

Liquid N,N,N',N'-tetramethyl-ethane-1,2-diamine (tmeda) was intercalated into preprepared C(6)Li or C(12)Li. X-ray diffraction from the ternary compound indicates an identity period of 11.5 Å. The (13)C NMR line shifts show that tmeda molecules form a screen between the graphene planes and the lithium ions. Small-angle X-ray scattering showed that no higher structural ordering was present but revealed a progressive roughening of the surfaces with successive intercalation of lithium and amine into the graphite galleries.

Structural Elucidation of tmeda‐Solvated Alkali Metal Diphenylamide Complexes

AbstractLithium, sodium and potassium salts of diphenylamine have been prepared by using a deprotonative route and characterised in both, solid state (by X‐ray crystallography) and solution (by NMR spectroscopic studies). In each case the metal atom's coordination sphere is completed by coordination to the synthetically important co‐ligand N,N,N′,N′‐tetramethylethylenediamine (tmeda). Complexes 1 and 2 [{(tmeda)M(NPh2)}2] (M = Li for 1, Na for 2) can be prepared by treating 1 mol.‐equiv. of the parent amine with an equimolar quantity of nBuM and tmeda in hexane solution. In the solid state, 1 and 2 are essentially isostructural, being dimeric with a four‐atom M–N–M–N framework. The coordination sphere of each M atom is completed by a bidentate tmeda molecule. Complex 3 [{(tmeda)3/2K(NPh2)}2] has been prepared in a similar way to 1 and 2 except that benzylpotassium has been utilised as the metallating agent. In addition, 4 mol‐equiv. of tmeda is required to fully solubilise the heavy alkali metal amide mixture. In the solid state, 3 exists as a polymeric array of dinuclear K–N–K–N rings. Akin to 1 and 2, the K atom is coordinated to a bidentate tmeda molecule; however, each K atom is also bound to another tmeda molecule that acts as a monodentate bridge, thus producing the coordination polymer. Crystalline 1 and 2 are soluble in C6D6; hence, NMR spectroscopic studies could be performed. These show that the solid‐state structure appears to stay intact in arene solution. On the other hand, 3 is not soluble in C6D6; so solution studies have been performed in [D8]thf. These studies reveal that 3 readily looses tmeda during in‐vacuo isolation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Contacted Ion-Pair Lithium Alkylamidoaluminates: Intramolecular Alumination (Al−H Exchange) Traps for TMEDA and PMDETA

Exploring the reactivity of mixed-metal synergic bases, it is found that the lithium TMP aluminate iBu3Al(TMP)Li functions as a dual TMP/alkyl base, exhibiting 2-fold AMMAl (alkali-metal-mediated alumination) toward TMEDA to yield the heterobimetallic bis-(deprotonated TMEDA) derivative [Li{Me2NCH2CH2N(Me)CH2}2Al(iBu)2] (2). In contrast, the amide enriched aluminate iBu2Al(TMP)2Li acts as only a single-fold amido base toward TMEDA or PMDETA to afford the amine-deprotonated derivatives [Li{Me2NCH2CH2N(Me)CH2}(TMP)Al(iBu)2] (4) and [Li{Me2NCH2CH2N(Me)CH2CH2N(Me)CH2}(TMP)Al(iBu)2] (5), respectively. On their own, the aluminum compounds iBu3Al or iBu2Al(TMP) are not sufficiently strong bases to metalate TMEDA or PMDETA, so in 2, 4, and 5, the α-deprotonations of TMEDA and PMDETA are synergic in origin, as the intramolecular communication between Li and Al appears to activate the TMP and iBu bases. This special behavior can be attributed to intramolecular proximity effects between the active base component (TMP or iBu) and the ligating TMEDA or PMDETA molecule. X-ray crystallography studies reveal 2 is a contacted ion-pair ate containing two α-aluminated TMEDA ligands, which chelate the lithium cation which is linked to the distorted tetrahedral Al center by two N bridges from the metalated junction of the TMEDA molecules. In contrast, 4 and 5 have a mixed NCH2-TMP bridging ligand set, completed by two terminal iBu ligands on Al and a chelating metalated TMEDA or PMDETA ligand attached to Li, respectively. In addition, the 1H, 7Li, and 13C{1H} spectra of 2 (recorded in C6D6 solutions), 4, and 5 (recorded in cyclohexane solutions-d12) are disclosed.

Thermodynamically Favored Anion Rearrangements in Li and Na Complexes of (S)-N-α-(Methylbenzyl)allylamine

Metalation of the chiral amine (S)-N-α-(methylbenzyl)allylamine with nBuM (M = Li, Na) leads to the formation of complexes with three distinct isomeric anion forms: allylamide [(PhC(H)CH3NCH2CH═CH2)]−, 1-aza-allyl [(PhC(H)CH3NC(H)CHCH3)]−, and aza-enolate [(PhC(═CH2)N(CH2CH2CH3)]−. The anionic form is dependent on the metal, the Lewis donor, and the thermal history of the complex. From their use in asymmetric syntheses and a previously described hmpa (hexamethylphosphoramide) complex, the allylamide form predominates with Li at room temperature in the presence of monodentate donors. The use of the bidentate donor tmeda (N,N,N′,N′-tetramethylethylenediamine) results in the crystallization and characterization of the 1-aza-allylic complex (S)-{[(PhC(H)CH3NC(H)CHCH3)Li}2·tmeda]∞, in which the allylamide moiety has undergone a 1,3-sigmatropic rearrangement. In the crystal structure, the tmeda molecules bridge rather than chelate the Li cations. The tridentate donor pmdta (N,N,N′,N′,N′′-pentamethyldiethylenetr...

Von N,N′‐Bis(1,1,3‐trisila‐2‐aza)‐ethylen‐diaminen zu N,N′‐Bis(1,3‐disila‐2‐lithiumamido)‐ethylensilylaminen – Synthesen, Kristallstrukturen, Reaktionen

AbstractFrom N,N′‐Bis(1,1,3‐trisila‐2‐aza)‐ethylene‐diamines to N,N′‐Bis(1,3‐disila‐2‐lithiumamido)‐ethylenesilylamines – Syntheses, Crystal Structures, ReactionsEthylenediamine reacts with the chloro‐functional tris(silyl)amines ClSiMe2N(SiMe3)SiMe2R in a molar ratio of 1:2 to give the N,N′‐bis(1,1,3‐trisila‐2‐aza)‐ethylenediamines, [CH2‐NH‐SiMe2‐N(SiMe3)SiMe2R]2, R = Me (1) and CMe3 (2). A structural isomer of 2 (CH2‐NSiMe2CMe3‐SiMe2‐NHSiMe3 = 3) is formed thermally, via 1,3‐silyl group migration from the Me3CSiMe2‐N‐SiMe3 group, at 200 °C. 1 reacts with butyllithium at 0 °C in a molar ratio of 1:2, forming the diamide 4, which was characterized as the monomer [CH2–NSiMe3–SiMe2–N(SiMe3)Li]2. Again two silyl groups migrate from the N(SiMe3)2 groups to the ethyleneamine nitrogen atoms. The lithium ions are coordinated by both amido groups forming a planar four‐membered ring. With THF as a solvent, each lithium ion of 4 coordinates one THF molecule. [CH2–NSiMe3–SiMe2–N–(SiMe3)Li–THF]2 (5) is obtained. With TMEDA as the donor base the cage structures of 4 and 5 are broken up to give an open‐chain dilithium salt [CH2–NSiMe3–SiMe2–N(SiMe3)Li–TMEDA]2 (6) with each lithium ion coordinated by one TMEDA molecule. Halosilanes and haloboranes react with 4, 5, and 6 to give an N,N′‐bis(1,1,3‐trisila‐2‐aza)‐ethylenesilylamine [CH2–NSiMe3–SiMe2–N(SiMe3)R]2, R = SiF2CMe3 (7), and N,N′‐bis(1‐bora‐1,3‐disila‐2‐aza)‐ethylenesilylamines, R = B(F)N(SiMe3)2 (8), B(F)[N(CMe2CH2)2CH2] (9).

A Structural and Computational Study of Synthetically Important Alkali‐Metal/Tetramethylpiperidide (TMP) Amine Solvates

Two heavy alkali-metal salts of the sterically demanding amine, 2,2,6,6-tetramethylpiperidine (TMPH), have been prepared using different methodologies. Complex 1, [((tmeda)Na(tmp))2] (TMEDA=N,N, N',N'-tetramethylethylenediamine), can be synthesized by a deprotonative route. This is achieved by reacting butylsodium with TMPH in the presence of excess TMEDA in hexane. The potassium congener [((tmeda)K(tmp))2] (2), can be prepared by treating KTMP (made using a metathesis reaction between LiTMP and potassium tert-butoxide) with an excess of TMEDA in hexane. In the solid state, 1 and 2 are essentially isostructural. They are discretely dimeric and their framework consists of a four-membered M-N-M-N ring (M=Na or K, N=TMP). Due to the high steric demand of the TMP ligand, the TMEDA molecules bind to the metal centers in an asymmetric manner. In 2, each of the coordination spheres of the metals is completed by an agostic K...CH3(TMP) interaction. DFT calculations at the B3 LYP/6-311G** level give an insight into why 1 and 2 adopt dramatically different structures from their previously reported, "open-dimeric", lithium counterpart. The theoretical work also focuses on the TMEDA-free parent amide complexes and reveals that the energy difference for the formation of [(M(tmp))x] (in which, M=Li or Na, x=3 or 4; and M=K, x=2, 3 or 4) are small.

Gas‐Phase Study on the CC Coupling of Naphthol Catalyzed by CuII⋅TMEDA: Evidence for the Key Role of Binuclear Clusters

The mechanism of oxidative coupling of two naphthol molecules to form binaphthol catalyzed by Cu(OH)ClTMEDA (TMEDA=N,N,N',N'-tetramethylethylenediamine) was approached by means of a gas-phase model system. Concise evidence is provided that the coupling reaction proceeds in clusters with two Cu(II) centers, whereby the intermediacy of free naphthoxy radicals in the coupling step is avoided. In the absence of TMEDA, the cluster is bound via a bridging counterion and the coupling reaction is followed by cluster cleavage. The coordination of one or two TMEDA molecules to the reactive complex results in more efficient coupling of naphthol molecules, and moreover, the binuclear cluster is also conserved after the reaction is completed. The effect of TMEDA is twofold: First, it supports clustering of copper and, second, as a ligand bound to a copper center in the reactive complex, it weakens the bond between copper and the naphtholato ligand such that the naphtholato unit is more prone to undergo C--C coupling. Furthermore, a pronounced counterion effect is found that correlates well with condensed-phase data: weakly bridging counterions (e.g., NO3(-)) yield less stable dicopper clusters and the coupling reaction hardly occurs, whereas better bridging counterions (e.g., Cl(-) or Br(-)) provide more stable clusters that make the coupling reaction more efficient.

Co-complexes of ortho-dilithiated thiophenol or 2-trimethylsilylthiophenol with lithiated TMEDA molecules: synthesis, crystal structures and theoretical studies (TMEDA = N,N,N′,N′-tetramethylethylenediamine)

When an excess of nBuLi was used in the ortho-dilithiation of thiophenol or 2-trimethylsilylthiophenol in the presence of TMEDA (TMEDA = N,N,N',N'-tetramethylethylenediamine), deprotonation of TMEDA occurred and crystals of [Li3{(2-S-C6H4)(CH2MeNCH2CH2NMe2)(TMEDA)}]2 (1) or [Li4{(2-S-3-SiMe3-C6H3)(CH2MeNCH2CH2NMe2)2(TMEDA)}] (2) were obtained. Molecular orbital calculations on gas-phase 1 and 2 at the DFT B3LYP/6-31G(d) level reproduce the experimental structures fairly well. In spite of the short Li...Li distances, total electron density representations do not support the existence of Li...Li interactions.

The Structural Chemistry of N‐Monolithium Borazines

AbstractTrimethylborazine (Me3B3N3H3, 1) reacts with RLi (R = nBu, tBu) in hexane solution by alkyl group exchange to give a mixture of borazines Me3–nRnB3N3H3. In contrast, deprotonation of 1 to Me3B3N3H2Li (2) occurs upon treatment with MeLi in diethyl ether solution or RLi (R = nBu, tBu) complexed with tetramethylethylenediamine (TMEDA), pentamethyldiethylentriamine (PMDTA), or trimethylhexahydrotriazine (TMTA) in hexane solution, to give solvates of 2. [(Me3B3N3H2)Li(OEt2)] (2a), [(Me3B3N3H2)Li(tmta)] (2c), and [(Me3B3N3H2Li)4(tmeda)3] (2b) contain dimeric units of 2. In the case of 2b two of these dimers are bridged by one tmeda molecule, while the other two are coordinated to a lithium atom of one of its dimeric units, respectively. This molecule therefore contains tri‐ and tetracoordinated Li atoms. In contrast, [(Me3B3N3H2)Li(pmdta)] (2c) is monomeric. The N‐lithiation leads to a distortion of the planar B3N3 ring system: the B–N bonds at the metallated N atoms are short, the next opposite B–N pair is the longest, followed by a shorter B–N bond involving the B atom in the para position. However, all B–N bonds are longer than in the parent compound 1. Reaction of tBu3B3N3H3 (3) with tBuLi in the presence of triisopropylhexahydrotriazine (TIPTA) in hexane leads to the salt [(tipta)2Li][tBu4B3N3H3] (4), while deprotonation occurs with tBuLi(tmta) to give monomeric [(tBu3B3N3H2)Li(tmta)] (5) after refluxing the reaction mixture. Similarly, (Me2N)3B3N3H3 (6) can be deprotonated with RLi in the presence of TMTA to give monomeric [{(Me2N)3B3N3H2}Li(tmta)] (7b). The N‐lithiation has almost no influence on the shielding of the boron nucleus of the borazine nuecleus. Attempts to obtain di‐ and trilithiated 1 as pure compounds failed: alkyl group exchange and borate formation as well as destruction of the borazine ring were detected by NMR spectroscopy. However, treatment of these reaction mixtures with MeBr gave Me3B3N3NH3–nMen (n = 0–3). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Di-mu-cyanato-bis[(cyanato-kappaN)(tetramethylethylenediamine-kappa2N,N')copper(II)] and catena-poly[[mu3-cyanato-kappa3O:N:N-bis[(cyanato-kappaN)(1,3-diaminopropane-kappa2N,N')copper(II)]]-mu3-cyanato-kappa3N:N:O

The two title Cu(II) complexes, [Cu(2)(NCO)(4)(tmeda)(2)] (tmeda is tetramethylethylenediamine, C(6)H(16)N(2)), (I), and [Cu(NCO)(2)(pn)](n) (pn is 1,3-diaminopropane, C(3)H(10)N(2)), (II), have been synthesized and their crystal structures determined. In (I), which lies about an inversion centre, each Cu centre possesses a distorted tetragonal-pyramidal geometry with four basal N atoms from two cyanate anions [Cu-N = 1.945 (2) and 1.948 (3) A] and one tmeda molecule [Cu-N = 2.053 (2) and 2.071 (2) A], and one axial O atom [Cu-O = 2.737 (3) A] from another cyanate anion. The two neighbouring Cu atoms in (I) are joined by a pair of cyanates in an end-to-end fashion, forming a dimer. In (II), each Cu centre adopts a distorted square-bipyramidal geometry, with four equatorial N atoms from two cyanates [Cu-N = 1.988 (2) and 2.007 (3) A] and a pn ligand [Cu-N = 1.996 (3) and 2.011 (3) A], and one apical N atom [Cu-N = 2.437 (3) A] and an apical O atom [Cu-O = 2.900 (3) A] from two cyanates. In contrast with (I), the two neighbouring Cu atoms in (II) are bridged by two cyanates in an end-on fashion, to form a centrosymmetric dimeric unit. These units are further crosslinked, forming a two-dimensional network structure, via weak interactions between the bridging cyanate O atom and a neighbouring Cu atom, plus interactions of the amine H atoms with the cyanate O atoms and the terminal cyanate N atom.

Aggregation patterns in alpha,alpha'-stabilized carbanions: assembly of a sodium cage polymer by slip-stacking of dimers.

The alpha,alpha'-stabilized carbanion complexes [PhSO(2)CHCNNa.THF], 3, [t-BuSO(2)CHCNNa], 4, [PhSO(2)CHCNK], 5, [t-BuSO(2)CHCNK], 6, and [MeSO(2)CHCNLi.TMEDA], 7, have been synthesized via the metalation of the parent (organo)sulfonylacetonitriles by BuLi, BuNa, or BnK in THF solution (or THF/TMEDA in the case of 7). In addition, complexes 3 and 7 have been characterized by single-crystal X-ray analyses and have been found to adopt related structures in the solid state. Complex 7 is a molecular dimer containing a central 12-membered (OSCCNLi)(2) ring core, with each metal rendered tetracoordinate by binding to a chelating TMEDA molecule. As found in related complexes, no direct carbanion to lithium contacts are present in the structure of 7. Complex 3 forms a polymeric cage structure composed of associated "dimeric" (OSCCNNa)(2) rings, similar to those found in 7. The larger sodium cations, and the presence of only one THF molecule/metal, allow additional contacts with the anions, leading to hexacoordination at the metal centers. These contacts include long-range transannular Na-N interactions (2.8042(14) A) across the central dimeric ring and "interdimer" Na-C connections (2.8718(15) A). Dissolution of complexes 3-6 and their lithiated derivatives [PhSO(2)CHCNLi.TMEDA], 1, and [t-BuSO(2)CHCNLi.THF], 2, in DMSO-d(6) results in almost identical chemical shifts for each type of ligand. This suggests that charge-separated complexes of the form [RSO(2)CHCN](-)[M(DMSO-d(6))(n)()](+) are formed in highly polar solution.

Solution and solid‐state structures of lithiated cyclic phosphonates

Spectroscopic analysis of lithiated cyclic phospho-nates belonging to the 1,3,2-dioxaphosphorinane 2-oxide class have been examined by NMR spectroscopy in THF and by single-crystal X-ray crystallography. Lithio P-benzyl-1,3,2-dioxaphosphorinane 2-oxide (Li+7−) and lithio P-isopropyl-1,3,2-dioxaphosphorinane 2-oxide (Li+8−) are characterized by freely rotating, sp2-hybridized anions devoid of lithium–carbon contacts. The anions are most likely dimers linked through oxygen-lithium bridges. The P-isopropyl compound crystallized from TMEDA/THF as a C-lithiated dimer in which each lithium bridges a carbon and an oxygen and is solvated by one TMEDA molecule. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:209–218, 1998

Solution and solid-state structures of lithiated cyclic phosphonates

Spectroscopic analysis of lithiated cyclic phospho-nates belonging to the 1,3,2-dioxaphosphorinane 2-oxide class have been examined by NMR spectroscopy in THF and by single-crystal X-ray crystallography. Lithio P-benzyl-1,3,2-dioxaphosphorinane 2-oxide (Li+7−) and lithio P-isopropyl-1,3,2-dioxaphosphorinane 2-oxide (Li+8−) are characterized by freely rotating, sp2-hybridized anions devoid of lithium–carbon contacts. The anions are most likely dimers linked through oxygen-lithium bridges. The P-isopropyl compound crystallized from TMEDA/THF as a C-lithiated dimer in which each lithium bridges a carbon and an oxygen and is solvated by one TMEDA molecule. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:209–218, 1998

(TM EDA)2Li4Cl4(H2O)2]·2 TMEDA: stabförmige vierkernige Li-Komplexe verknüpft durch TMEDA / [(TM EDA)2Li4Cl4(H2O)2]·2 TMEDA: Stick-Like Tetranuclear Li Complexes Connected by TMEDA

Abstract The title compound 1 was synthesized by the reaction of LiCl with TM EDA (N,N,N′,N′- tetramethylethylendiamine) and water at 120 °C in boiling TM EDA. 1 was crystallized at - 30 °C as colorless crystals and characterized by NMR and IR spectroscopy as well as by an X-ray structure determination. 1 is a polymer in the solid state, built up by an alternating arrangement of stick-like tetranuclear Li complexes and two TMEDA molecules. The complexes and the TMEDA molecules are connected by hydrogen bridges in infinite chains.

Röntgenstrukturuntersuchung von α‐(Trimethylsilyl)benzyllithium·Tetramethylendiamin [C6H5CH(SiMe3)Li·TMEDA] und α‐(Phenylthio)‐benzyllithium·3 Tetrahydrofuran [C6H5CH(SPh)Li·(THF)3] – zwei zentral‐chirale Benzyllithium‐Verbindungen

Crystal Structure of α‐(Trimethylsilyl)benzyllithium·Tetramethylethylendiamin [C6H5CH(SiMe3)Li·TMEDA] und α‐(Phenylthio)‐benzyllithium·3 Tetrahydrofuran [C6H5CH(SPh)Li – (THF)3] – Two Benzyllithium Compounds with Central ChiralityThe crystal structure analyses of [C6H5CH(SiMe3)Li·TMEDA] (6) and of [C6H5CH(SPh)Li·(THF)3] (7, in which the positions of the benzylic hydrogen atoms have been determined experimentally, reveal compounds with pyramidal benzylic carbon atoms. In 6 lithium is λ2‐bound to Cipso and α of the substituted benzylic anion which leads, together with the TMEDA molecule, to a tetra‐coordinated lithium atom. In 7 only one Li – C bond is formed, namely that to Cα. Additional coordination with three THF molecules results also in a tetracoordinated lithium atom, The extent of the pyramidalization in 6 and 7 is qualitatively in agreement with quantum‐mechanical ab initio calculations [G86, MP2/6‐311+ + G(d,p)].

Crystal structures of bis(cyclopentadienyldicarbonyliron)sodium tetrahydrofuran and (cyclopentadienyldicarbonyliron)sodium tetramethylethylenediamine complexes

The extremely air-sensitive intermediate product [C 5H 5Fe(CO) 2] 2Na·4THF (I) and final product [C 5H 5Fe(CO) 2]Na·TMEDA (II) have been obtained by the reduction of [C 5H 5Fe(CO) 2] 2 by Na/Hg. Their crystal structures have been determined at low temperature. The crystals belong to the monoclinic space group P2 1/ n with a 10.155(5), b 17.121(4), c 18.667(6) Å, and β 97.61(3)° for I, and to the orthorhombic space group P2 12 12 1 with a 6.001(4), b 10.644(6) and c 24.214(11) Å for II, respectively. Complex I has a linear chain structure with dimer anion [C 5H 5Fe(CO) 2] 2 − and complex cation (Na·4THF) + connected alternately by NaO(CO) bonds. Complex II has a spiral chain structure in which Na + with a TMEDA molecule and (C 5H 5Fe) − are bridged by carbonyl groups. A possible reaction mechanism based on the crystal structure is proposed.

Preparation and crystal structure of a novel lithium thiolate cluster: [Li14(SCH2Ph)12S(TMEDA)6](TMEDA = tetramethylethylenediamine)

The title compound, simply prepared from benzyl mercaptan, n-butyl-lithium, and TMEDA in toluene (TMEDA = tetramethylethylenediamine), crystallises as an unusual type of cluster, in which a central S atom is surrounded by a distorted cube of Li atoms, each edge of which is bridged by a benzyl thiolate group such that the twelve S atoms form a cubo-octahedron; a further six Li atoms form a large outer octahedron, each one sitting above an S–S edge, with tetrahedral co-ordination completed by a TMEDA molecule.