Tetramethylethylenediamine Ligands Research Articles

Formation of N,N,N',N'-tetramethylethylenediamine via coupling of the two charge reversed C-N bonds of Me3NO in the presence of an Eu(II) bis(trimethylsilyl)amide complex.

An N,N,N',N'-tetramethylethylenediamine (TMEDA) complex of Eu(II) was synthesized via an unprecedented self-aminomethylation of Me3NO in the presence of Eu[N(SiMe3)2]2(THF)2. The neutral TMEDA ligand is formed via the coupling of two charge reversed carbon centres from the same precursor Me3NO. In contrast, the reactions of LnII[N(SiMe3)2]2(THF)2 (Ln = Yb, Sm) with Me3NO led to the oxygen-bridged dinuclear complexes of Ln(III).

Bis(acetylacetonato-κ2 O,O′)(N,N,N′,N′-tetramethylethylenediamine-κ2 N,N′)magnesium(II)

The title complex, [Mg(C5H7O2)2(C6H16N2)], has been synthesized from magnesium acetylacetonate [Mg(acac)2] and tetramethylethylenediamine (TMEDA) in n-hexane. The monomeric complex consists of a central magnesium(II) atom, which is surrounded nearly octahedrally by two chelating acetylacetonato ligands and one chelating TMEDA ligand. [Mg(C5H7O2)2(C6H16N2)] is isotypic with its Zn analogue.

(Invited) Ligand Addition for Thermal Atomic Layer Etching of Metals

Thermal atomic layer etching (ALE) is typically defined by sequential surface reactions. Thermal ALE can be viewed as the reverse of atomic layer deposition (ALD). Thermal ALE is usually performed with two steps: modification of the surface and removal of the modified surface. The modification can be oxidation, fluorination, or chlorination. The removal step is often a ligand-exchange reaction, creating stable volatile species that leave the surface, leading to a net removal of material. For example, aluminum oxide can be etched using thermal ALE with HF to fluorinate the surface and trimethylaluminum (TMA) to exchange methyl ligands for surface fluoride ligands, resulting in volatile Al(CH3)xFy species.Thermal ALE of metals is particularly challenging because the oxidation state of the metal must be changed to match the oxidation state of the volatile metal etch product. This oxidation is performed in the modification step of thermal ALE. After changing the oxidation state, the metal then produces a stable complex during the volatile release reaction. In this work, Ni and Co ALE are developed by modifying the metal via chlorination using SO2Cl2. Subsequently, the metal is removed by addition of an L ligand to the metal center to create a stable, volatile etch product, MClxLy (Figure 1). The L ligands explored in this work were PMe3 and tetramethyl ethylenediamine (TMEDA).The chlorination and ligand-addition approach for metal ALE is based on the Covalent Bond Classification (CBC) method. X ligands are one-electron donors like Cl and other halogens. L ligands are two-electron donors like PMe3. TMEDA is a bidentate ligand. One TMEDA ligand acts as two L ligands since TMEDA binds to the metal center through the lone electron pairs on the two nitrogen groups. According to the CBC method, nickel complexes typically have NiX2L3 or NiX2L2 configurations. Likewise, cobalt complexes are typically found in the CoX2L4, CoX2L2, or CoX3L3 configurations. The goal for Ni or Co ALE is to create these volatile metal compounds using sequential SO2Cl2 and L ligand surface reactions.Both Ni and Co ALE have been studied with in situ quartz crystal microbalance (QCM) and X-ray reflectivity (XRR) to determine the etch rates. Quadrupole mass spectrometry (QMS) was also employed to determine the volatile metal-containing etch species. Using SO2Cl2 and PMe3, Ni etch rates varied from 0.1-3 Å/cycle at temperatures from 75-200 °C. QMS measurements also identified NiCl2(PMe3)2 (NiX2L2) as the stable volatile etch product. Cobalt ALE using SO2Cl2 and TMEDA displayed etch rates from 1-12 Å/cycle at temperatures from 175-300 °C. QMS measurements also detected CoCl2(TMEDA) (CoX2L2) as the stable volatile etch product. In addition, cobalt can be etched using SO2Cl2 and PMe3 from 70-200 °C, with etch rates between 2-4 Å/cycle. These two Co ALE pathways with TMEDA and PMe3 are complementary with TMEDA useful at higher temperatures and PMe3 useful at lower temperatures.Many other X and L ligands could be used for the halogenation and ligand-addition reactions during metal thermal ALE. The CBC method can be used as a guide to develop the X ligands for surface modification and the L ligands for volatile release. This approach should lead to various other metal ALE processes. Selective metal thermal ALE should also be possible using different X and L ligands. Figure 1

Structure of a subnanometer-sized semiconductor Cd14Se13 cluster

Structure of a subnanometer-sized semiconductor Cd14Se13 cluster

Crystal structure and Hirshfeld surface analysis of a copper(II) complex containing 2-nitro-benzoate and tetra-methyl-ethylenedi-amine ligands.

The reaction of copper(II) sulfatepentahydrate with 2-nitro-benzoic acid and N,N,N',N'-tetra-methyl-ethylenedi-amine (TMEDA) in basic solution produces the complex bis-(2-nitro-benzoato-κO)(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')copper(II), [Cu(C7H4NO4)2(C6H16N2)] or [Cu(2-nitro-benzoate)2(tmeda)]. Each carboxyl-ate group of the 2-nitro-benzoate ligand is coordinated by CuII atom in a monodentate fashion and two TMEDA ligand nitro-gen atoms are coordinate by the metal center, giving rise to a distorted square-planar coordination environment. In the crystal, metal complexes are linked by centrosymmetric C-H⋯O hydrogen bonds, forming ribbons via a R 2 2(10) ring motif. These ribbons are linked by further C-H⋯O hydrogen bonds, leading to two-dimensional hydrogen-bonded arrays parallel to the bc plane. Weak π-π stacking inter-actions provide additional stabilization of the crystal structure. Hirshfeld surface analysis, dnorm and two-dimensional fingerprint plots were examined to verify the contributions of the different inter-molecular contacts within the supra-molecular structure. The major inter-actions of the complex are O⋯H/H⋯O (44.9%), H⋯H (34%) and C⋯H (14.5%).

Crystal structure and Hirshfeld surface analysis of one-dimensional copper(II) coordination polymer incorporating succinate and tetra-methyl-ethylene-diamine ligands.

The reaction of copper nitrate with succinic acid (succH) and N,N,N',N'-tetra-methyl-ethylenedi-amine (TMEDA) in basic solution produces the complex catena-poly[[[(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')copper(II)]-μ-succinato-κ2 O 1:O 4] tetra-hydrate], {[Cu(C4H4O4)(C6H16N2)]·4H2O} n or {[Cu(succ)(tmeda)]·4H2O} n . Each carboxyl-ate group of the succinate ligand coordinates to a CuII atom in a monodentate fashion, giving rise to a distorted square-planar geometry. The succinate ligands bridge the CuII centres, forming one-dimensional polymeric chains. Hydrogen bonds between the ligands and water mol-ecules link these chains into sheets that lie parallel to the ac plane. Hirshfeld surface analysis, d norm and two-dimensional fingerprint plots were examined to verify the contributions of the different inter-molecular contacts within the supra-molecular structure.

Syntheses and crystal structures of three [M(acac)2(TMEDA)] complexes (M = Mn, Fe and Zn).

The complexes bis-(acetyl-acetonato-κ2 O,O')(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')manganese(II), [Mn(C5H7O2)2(C6H16N2)], bis-(acetyl-acetonato-κ2 O,O')(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')iron(II), [Fe(C5H7O2)2(C6H16N2)], and bis-(acetyl-acetonato-κ2 O,O')(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')zinc(II), [Zn(C5H7O2)2(C6H16N2)], were synthesized from the reaction of the corresponding metal acetyl-acetonates [M(acac)2(H2O)2] with N,N,N',N'-tetra-methyl-ethylenedi-amine (TMEDA) in toluene. Each of the complexes displays a central metal atom which is nearly octa-hedrally surrounded by two chelating acac and one chelating TMEDA ligand, resulting in an N2O4 coordination set. Despite the chemical similarity of the complex units, the packing patterns for compounds 1-3 are different and thus the crystal structures are not isotypic.

Crystal structure of (4-fluoro-phenyl-κC (1))iodido-(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ(2) N,N')palladium(II).

In the title compound, [Pd(C6H4F)I(C6H16N2)], the PdII atom is coordinated by two N atoms from the N,N,N′,N′-tetra­methyl­ethylenedi­amine ligand, a C atom of the 4-fluoro­phenyl group and an iodide ligand in a distorted square-planar geometry, with an average deviation from the least-squares plane through the ligand donor atoms of 0.0159 (2) Å. The angles about the PdII atom range from 83.35 (16) to 178.59 (11)°. In the crystal, weak C—H⋯F and C—H⋯I hydrogen bonds link the mol­ecules into sheets in the bc plane.

Cis-Diiodido(N,N,N′,N′-tetramethylethylenediamine-κ2N,N′)palladium(II)

In the title complex, cis-[PdI2(C6H16N2)], the PdII atom lies on a crystallographic twofold rotation axis and is four-coordinated by the two N atoms of a chelating N,N,N′,N′-tetra­methyl­ethylenediamine ligand [Pd—N = 2.125 (3) Å] and two I atoms [Pd—I = 2.5833 (4) Å], displaying a distorted square-planar geometry (r.m.s. deviation = 0.005 Å), imposed by the small bite of the chelating ligand [N—Pd—N angle = 84.68 (18)°].

Effects of Metal-Organic Chemical Vapour Deposition grown seed layer on the fabrication of well aligned ZnO nanorods by Chemical Bath Deposition

Well aligned, long and uniform ZnO nanorods have been reproducibly fabricated adopting a two-steps Metal-Organic Chemical Vapour Deposition (MOCVD) and Chemical Bath Deposition (CBD) fabrication approaches. Thin (< 100 nm) ZnO buffer layers have been seeded on silicon substrates by MOCVD and ZnO layers have been subsequently grown, in form of well textured nanorods, using CBD. It has been found that the structure and thickness of the seed layer strongly influence the final morphology and the crystal texturing of ZnO nanorods as well as the CBD growth rate. There is, in addition, a strong correlation between morphologies of CBD grown ZnO nanorods and those of the seed layer underneath. Thus, nanorods deposited over low temperature MOCVD buffer layers are less homogeneous in lateral dimensions and poorly vertically oriented. On the contrary, higher temperature nano-dimensional ZnO seeds favour the CBD growth of almost mono-dimensional homologue nanorods, with an adequate control of the lateral transport of matter. The nanorod aspect ratio values decrease upon increasing the deposition temperatures of the seed layers. Moreover, the nanorods length can be tailored either by adjusting the CBD growth time or by changing concentration of the N,N,N′,N′-tetramethylethylenediamine ligand used in the CBD process. In particular, at high concentrations, the CBD process is faster with a greater global aspect ratio in agreement with a preferential one-dimensional growth of the ZnO nanostructures. Finally, these ZnO nanorod arrays possess good optical quality in accordance to the photoluminescence properties.

ChemInform Abstract: Structure and Reactivity of Lithium Diisopropylamide in the Presence of N,N,N′,N′-Tetramethylethylenediamine.

Lithium diisopropylamide (LDA) crystallizes from N,N,N',-tetramethylethylenediamine (TMEDA)/hexane mixtures as an infinite array of dimers linked by bridging (nonchelating) TMEDA ligands. 6Li and I5N NMR spectroscopic studies reveal that LDA in neat TMEDA exists as a cyclic dimer bearing a single $-coordinated TMEDA ligand on each lithium. The equilibrium of solvent-free LDA and the TMEDA-solvated dimer shows a very strong temperature dependence. TMEDA coordinates readily only at low temperature. High TMEDA concentrations are required to saturate the lithium coordination spheres at ambient temperatures. One equivalent of THF readily displaces TMEDA from the coordination sphere to produce the dimeric LDA/THF solvate characterized previously. Kinetics of metalation of 2-methylcyclohexanone N,N-dimethylhydrazone monitored by Fourier-transform infrared (FT-IR) spectroscopy are consistent with a rapid, spectroscopically undetectable dimer-monomer preequilibrium followed by rate-limiting proton transfer. The reaction rate is independent of the TMEDA concentration. Related spectroscopic and rate studies using dimethylethylamine lacking the capacity to chelate show strong parallels with the TMEDA data. We conclude that TMEDA chelates of LDA are of no measurable consequence throughout the reaction coordinate. MNDO calculations of THF and TMEDA solvates of Me,NLi and LDA monomers and dimers qualitatively support the conclusions derived from the experimental data.

Coordination polymers of Mn(II) and Cu(II) orotate with 2-methylimidazole and N, N, N′, N′-tetramethylethylenediamine ligands: Syntheses, spectroscopic and thermal analyses and crystal structures of mer-[Mn(μ-HOr)(H 2O)(2-meim) 2] n and thermochromic {[Cu(μ-HOr)(tmen)] · 1.5H 2O} n complexes

The syntheses, FT-IR and UV–Vis spectra, thermal analyses and crystal structures of Mn(II) and Cu(II) orotate coordination polymers with 2-methylimidazole (2-meim) and N,N,N′ ,N′-tetramethylethylenediamine (tmen) ligands are described. The orotate ligand acts as a bridging ligand with two different coordination modes, the { mer-[Mn(μ-HOr)(H 2O)(2-meim) 2]} n ( 1) complex displays an linear chain structure in which each Mn(II) ion exhibits a distorted octahedral coordination by a tridentate orotate, two 2-meim and one aqua ligand. In {[Cu(μ-HOr)(tmen)] · 1.5H 2O} n ( 2), the Cu(II) ion is coordinated by a tridentate orotate and one bidentate tmen ligand, and exhibits a square pyramidal geometry. These polymer chains are linked by hydrogen-bond interactions forming a three-dimensional network. Complex 2 exhibits an irreversible thermochromic effect. After dehydration, the color of the complex changes from blue to green.

Synthesis and reactions of heterodinuclear organopalladium complex having an unsymmetrical PN ligand

Novel heterodinuclear organopalladium complexes having an unsymmetrical PN ligand (Et 2NC 2H 4PPh 2-κ 2 N, P)RPd–ML n (ML n = Co(CO) 4; R = Me ( 2a), Ph ( 2b), ML n = MoCp(CO) 3; R = Ph ( 3b)) are synthesized by metathetical reactions of PdRX(Et 2NC 2H 4PPh 2-κ 2 N, P) (X = I, NO 3) with Na +[ML n ] −. Reversible dissociation of the Pd–N bond in 3b is revealed by variable temperature NMR studies. Reactions of 2a and 2b with CO yield corresponding acyl complexes (Et 2NC 2H 4PPh 2-κ 2 N, P)(RCO)Pd–Co(CO) 4 (R = Me ( 5a), Ph ( 5b)). Rate of CO insertion for 2a and 2b is significantly faster than those for mononuclear methylpalladium complex, PdMeI(Et 2NC 2H 4PPh 2-κ 2 N, P) ( 1a), and methylpalladium–cobalt complex with a 1,2-bis(diphenylphosphino)ethane (dppe) ligand, (dppe-κ 2 P, P′)MePd–Co(CO) 4 ( 6a). 5a smoothly reacts with nucleophiles such as diethylamine, methanol and benzenethiol to give corresponding amide, ester and thioester, respectively. These reactions of 5a are also significantly faster than those of corresponding mononuclear analogues and the similar heterodinuclear complexes with symmetrical bidentate ligands such as 1,2-bis(diphenylphosphino)ethane or N, N, N′, N′-tetramethylethylenediamine ligand.

Catena-Poly[[bis(μ-2,6-dimethylpiperidinido-N:N)dilithium]-μ-(N,N,N',N'-tetramethylethylenediamine-N:N')

The title compound, [Li-2(C7H14N)(2)(C6H16N2)](n), is a chain polymer in which strictly planar Li2N2 rings incorporating 2,6-dimethylpiperidinido ligands are linked by N,N,N',N'-tetramethylethylenediamine ligands in a rare bridging role. The Li atom is planar three-coordinate. The internal ring angles are obtuse [107.89(11)degrees] at lithium and acute [72.11(11)degrees] at nitrogen, as is commonly found for lithium amide ring structures.

Binding of Diamines to n-Butyllithium Dimers: Relative Solvation Energies and Evidence of Correlated Solvation

Polyamines such as N,N,N′,N′-tetramethylethylenediamine (TMEDA) have had an enormous impact within organolithium chemistry.1,2 However, despite extensive structural and mechanistic studies,2,3 it is still not clear how chelating ligands influence organolithium structure and reactivity.3 As part of an effort to understand structure-reactivity relationships in organolithium chemistry, we have been investigating the role of TMEDA and related chelating ligands.4 We describe herein spectroscopic investigations of n-butyllithium (n-BuLi) solvated by an assortment of vicinal diamines.5,6 These studies reveal highly liganddependent solvation energies and correlated solvation effects.

Tetrachlorobis(N,N,N',N'-tetramethylethylenediamine-N,N')thorium(IV)

The title compound, [ThCl4(C6H16N2)2], displays an approximate dodecahedral geometry in the solid state, with the Th atom binding to four Cl ligands and to the four N atoms of two tetramethylethylenediamine ligands. The Th—Cl and Th—N distances are in the ranges 2.683 (3)–2.692 (3) Å and 2.800 (7)–2.825 (9) Å, respectively.

(2-Thioxo-1,3-dithiole-4,5-dithiolato)(N,N,N',N'-tetramethylethylenediamine)nickel(II)

The title compound, [Ni(C3S5)(C6H16N2)], contains a four-coordinate Ni atom which is bonded to two S atoms from the 2-thioxo-1,3-dithiole-4,5-dithiolate (dmit) ligand and to the two N atoms of the N,N,N',N'-tetramethylethylenediamine ligand. The mean Ni—S and Ni—N bond lengths are 2.169 (4) and 2.003 (9) Å, respectively.

1‐Lithio‐2,2‐diphenyl‐1‐(phenylsulfonyl)ethen: Synthese und Kristallstruktur

Syntheses and Crystal Structure of 1‐Lithio‐2,2‐diphenyl‐1‐(phenylsulfonyl)etheneCrystals of [1‐lithio‐2,2‐diphenyl‐1‐(phenylsulfonyl)ethene]– N,N,N′,N′ ‐tetramethylethylenediamine (2/2) (2) were prepared by addition of BuLi to 1,1‐diphenyl‐2‐(phenylsulfonyl)ethene (1) in the presence of N,N,N′,N′ ‐tetramethylethylenediamine (TMEDA) at low temperature. The X‐ray structure analysis shows a centrosymmetric dimer bridged over an eight‐membered (LiOSO)2 ring. There are no Li–C contacts to the C(α) atoms. Both Li cations are tetracoordinated via the sulfonyl O‐atoms and the N‐atoms of the TMEDA ligand. The X‐ray structure analysis of 1,1‐diphenyl‐2‐(phenylsulfonyl)ethene (1) also was determined to compare interatomic distances and angles.

Dynamic Behaviour of Tetramethylethylene Diamine (TMEDA) Ligands in Solid Organolithium Compounds: A Variable Temperature 13C and I5N CP/MAS NMR Study

Abstract The dynamic behaviour of tetramethylethylene diamine (TMEDA) ligands in three organometallic complexes, dimeric phenyllithium, [Li(tmeda)μ-Ph]2 (1), lithium cyclopentadienide, [Li(tmeda)]C5H5 (2), and dilithium naphthalendiide, trans-[Li(tmeda)]2C10H8 (3), has been studied by CP/MAS 13C and 15N as well as 7Li MAS NMR spectroscopy of powdered samples. Two dynamic processes with free activation enthalpies of 40 and 68 kJ mol-1, respectively, were detected for 1. The first one can be assigned to ring inversion of the five-membered Li-TMEDA rings, while the second is caused by a complete rotation of the TMEDA ligands or a ring inversion of the central four-membered C-Li-C-Li metallacycle. Fast rotation of the ligands on the NMR time scale was found for 2, while 3 shows 180° ring flips of the Li-TMEDA groups, which are characterized by an energy barrier ΔG" (317) of 64 kJ mol-1

X-ray crystal, magnetic and spectroscopic studies of dicopper mixed-ligand complexes containing bridged bis(β-diketonate) and tetramethylethylenediamine ligands

Two dicopper(II) complexes, [Cu 2(tae)(tmed) 2]X 2, where tae = 1,1,2,2-tetra-acetylethanediide, tmed = tetramethylethylenediamine and X = NO − 3, BPh − 4, were synthesized. The X-ray crystal structure of the nitrate salt was determined. The two square planar basal planes containing the copper ions make a dihedral angle of 84.6° with each other. The nitrate ion is coordinated to each of the copper ions at the apex of a square pyramid. Variable temperature magnetic susceptibility measurements on the two complexes gave J values of − 17.6 (NO − 3) and −8.7 (BPh − 4) cm −1. The ESR and visible spectra of the tetraphenylborate salt are dependent on the solvent basicity.