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Lloyd T.J. Evans

Bio: Lloyd T.J. Evans is an academic researcher from University of Sussex. The author has contributed to research in topics: Amide & Lithium amide. The author has an hindex of 4, co-authored 6 publications receiving 36 citations.

Papers
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Journal ArticleDOI
TL;DR: A series of mono-and bis-amide scandium and yttrium compounds incorporating the furyl-substituted disilazide ligand, [N{SiMe2R}2] {i} (where R = 2-methylfuryl) have been synthesized as mentioned in this paper.

10 citations

Journal ArticleDOI
TL;DR: The catalytic activity of selected complexes in the polymerization of ethylene is reported, and the molecular structures of 1a, 1b, [3a]2, 4b, 5b and 6b have been solved using single-crystal X-ray diffraction techniques, indicating varying nuclearity of the complexes and hapticities for the amide ligands in the solid-state.
Abstract: The stoichiometric reaction between the previously described lithium amide salts, LiN(SiMe2R)2 [Li{i}, R = furyl, Li{ii}, R = 2-methylfuryl] and titanium(IV)chloride at low temperature afforded the mono-amide compounds Ti{i}Cl3 (1a) and Ti{ii}Cl3 (1b). The analogous zirconium derivatives Zr{i}Cl3 (3a) and Zr{ii}Cl3 (3b) were accessed via the reaction of excess trimethylsilylchloride with the mixed tetra-amide species, Zr{i}(NMe2)3 (2a) and Zr{ii}(NMe2)3 (2b). The bis-amide complexes Ti{ii}2Cl2 (4b), Zr{i}2Cl2 (5a) and Zr{ii}2Cl2 (5b) were synthesized in a straightforward salt metathesis reaction employing two equivalents of Li{i} or Li{ii} with the metal salts, MCl4(THF)2. The reactivity of the halide compounds 1 and 3–5 with a variety of alkylating agents was studied, with ligand transfer from the transition-element to the main group metal-alkyl reagent being the predominant reaction pathway. The reaction of 4b with MeLi was, however, partially successful affording the titanium(III) complex, Ti{ii}2X (X = Cl/Me, 6b′); this compound was subsequently made as the pure chloride 6b from the reaction of two equivalents of Li{ii} with TiCl3(THF)3. The targeted dialkyl species, Ti{ii}Me2 (7b), was successfully isolated from the reaction between the dichloride 4b and dimethylmagnesium. The molecular structures of 1a, 1b, [3a]2 [3b]2, 4b, 5b and 6b have been solved using single-crystal X-ray diffraction techniques, indicating varying nuclearity of the complexes and hapticities for the amide ligands in the solid-state. The catalytic activity of selected complexes in the polymerization of ethylene is reported.

8 citations

Journal ArticleDOI
TL;DR: In this paper, a range of furyl-substituted silylamides of the group 1 metals have been isolated and structurally characterized, in which the ability of the furyl group to coordinate to the metal is related to the size of the substituent in the 2-position.

7 citations

Journal ArticleDOI
TL;DR: In this article, the lithium salt of the bis-furyl substituted disilazide anion, Li{i] [{i} = N(SiMe2R)2 where R = 2-methylfuryl] has been examined as a ligand transfer reagent for the synthesis of group 2 (magnesium) and group 13 (aluminium) compounds.

6 citations

Journal ArticleDOI
TL;DR: The hexaphosphapentaprismane cage, (P6C4Bu4)-Bu-t ("Jaws"), can be readily opened by reaction with iodine at room temperature to afford the di-iodo derivative (I2P 6C4 Bu4)-bu-t which can be converted to the dimethyl derivative (Me2P6c4Bu 4)-Bu -t by treatment with LiMe.

5 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a review summarizes advances in the chemistry of bis(alkyl) rare-earth complexes and the methods of synthesis, structures, reactivity and catalytic activity of species complexes are considered.

77 citations

Journal ArticleDOI
TL;DR: The simultaneous presence of methyl groups at the C(2) and N(1) atoms of 2-acetylthiophene-N(1)-methylthiosemicarbazone (HattscN-Me) have facilitated the binding of triphenylphosphine in three-coordinate copper(i) halide complexes, which represent an unusual donor set of ligands, namely, triphensylph phosphine, sulfur of a thio-ligand and
Abstract: The influence of substituents at the C2carbon of N1-substituted thiosemicarbazones, {C4H3X–C2(CH3)N3–N2H–C1(S)N1HR2} (X = O, S) on the geometry of nickel(II) complexes has been investigated. The presence of a methyl group at the C2 position of 2-acetylfuran-N1-substituted thiosemicarbazones {(C4H3O)–C2(CH3)N3–N2H–C1(S)N1HR2, R2 = CH3, HaftscN–Me; C2H5, HaftscN–Et; C6H5, HaftscN–Ph} induces unusual coordination by the furan ring and yielded high spin octahedral nickel(II) complexes, [Ni(κ3-O, N3, S-aftscN–R2)2], CH31, C2H52, and 2[Ni((κ3-O, N3, S-aftscN–Ph)2] 3 (μeff = 2.98, 1; 2.96, 2; 2.92, 3). With 2-acetylthiophene-N1-substituted thiosemicarbazones, {(C4H3S)-C2(CH3)N3-N2H–C1(S)N1HR2, R2 = CH3, HattscN–Me; C2H5, HattscN–Et; C6H5, HattscN–Ph}, N3, S chelated low spin trans square planar complexes, {[Ni(κ3-O, N3, S-attscN–R2)2], R2 = CH3, 4; C2H5, 5; C6H5, 6} with pendant thiophene rings have been obtained. The bigger sized sulfur atoms of the thiophene rings form short intramolecular contacts with the deprotonated hydrazinic nitrogen atoms (S⋯N2) inhibiting its lability for possible coordination to nickel(II). Complexes have one independent molecule (1) or two independent molecules (2, 3) in their respective crystal lattices. The simultaneous presence of methyl groups at the C2 and N1 atoms of 2-acetylthiophene-N1-methylthiosemicarbazone (HattscN–Me) have facilitated the binding of triphenylphosphine in three-coordinate copper(I) halide complexes, [CuX(η1-S-HattscN–Me)(Ph3P)] (X, Br, 7; Cl, 8), which represent an unusual donor set of ligands, namely, triphenylphosphine, sulfur of a thio-ligand and a halide.

44 citations

Journal ArticleDOI
TL;DR: The reaction between a dialkyl-substituted alumanyl anion and [Y(CH 2 SiMe 3 ) 2 (thf) 3 ][BPh 4 ] resulted in the formation of (dialkylalumanyl)yttrium complex 2, which exhibits the first 2-center-2-electron (2c-2e) Al-Y bond.
Abstract: The reaction between a dialkyl-substituted alumanyl anion and [Y(CH2 SiMe3 )2 (thf)3 ][BPh4 ] resulted in the formation of (dialkylalumanyl)yttrium complex 2, which exhibits the first 2-center-2-electron (2 c-2 e) Al-Y bond. The 1 H and 13 C NMR spectra of 2 together with an X-ray crystallographic analysis indicated a C2v symmetrical structure. DFT calculations on 2 revealed that its LUMO consists of overlapping 3 p- and 4 d-orbitals of the Al and Y atoms, respectively, and that the HOMO-LUMO gap is narrow. The UV/Vis spectrum of 2 exhibited a visible absorption at 432 nm, which suggests that the strong σ-donating and π-accepting character of the three-coordinate dialkylalumanyl ligand generates a colored d0 -complex that does not contain any π-electrons.

24 citations

Journal ArticleDOI
TL;DR: In this article, a single-crystal structural characterization of the ytterbium(II) complex is presented, which suggests triple deprotonation of the macrocyclic ligand on metalation.

22 citations

Journal ArticleDOI
TL;DR: The structural chemistry of eleven donor complexes of the important Brønsted base potassium 1,1,2-diaminocyclohexane (KHMDS), depending on the donor, adopted one of five general structural motifs.
Abstract: The structural chemistry of eleven donor complexes of the important Bronsted base potassium 1,1,1,3,3,3-hexamethyldisilazide (KHMDS) has been studied. Depending on the donor, each complex adopted one of five general structural motifs. Specifically, in this study the donors employed were toluene (to give polymeric 1 and dimeric 2), THF (polymeric 3), N,N,N′,N′-tetramethylethylenediamine (TMEDA) (dimeric 4), (R,R)-N,N,N′,N′-tetramethyl-1,2-diaminocyclohexane [(R,R)-TMCDA] (dimeric 5), 12-crown-4 (dimeric 6), N,N,N′,N′-tetramethyldiaminoethyl ether (TMDAE) (tetranuclear dimeric 8 and monomeric 10), N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) (tetranuclear dimeric 7), tris[2-dimethyl(amino)ethyl]amine (Me6TREN) (tetranuclear dimeric 9) and tris{2-(2-methoxyethoxy)ethyl}amine (TMEEA) (monomeric 11). The complexes were also studied in solution by 1H and 13C NMR spectroscopy as well as DOSY NMR spectroscopy.

18 citations