Metal complexes as potential ligands : the deprotonation of aminephenolate metal complexes

The cationic nickel, copper and zinc complexes of tris-(2-hydroxybenzyl)-aminoethylamine (H6TrenSal) have been deprotonated using potassium hydroxide. The nickel complex can be sequentially deprotonated to form a series of compounds namely, [(H6TrenSal)Ni]+, [(H6TrenSal)Ni] and "[(H6TrenSal)Ni]K". The latter is isolated as a mixture of species namely [{(H6TrenSal)Ni}K(EtOH)]2, [{(H6TrenSal)Ni}K(EtOH)2-μ-OH2]2 and [{(H6TrenSal)Ni}K(EtOH)2-μ-EtOH]2, which co-crystallise in a roughly 50:27.5:22.5 ratio. In contrast the deprotonation of [(H6TrenSal)M]+ (M = Cu, Zn) results in the formation of tetrameric complexes [({(H6TrenSal)Ni}K(OH2)2)4(μ4-OH2)]

N-heterocyclic germylenes: structural characterisation of some heavy analogues of the ubiquitous N-heterocyclic carbenes

The X-ray crystal structures of three N-heterocyclic germylenes (NHGes) have been elucidated including the previously unknown 1,3-bis(2,6-dimethylphenyl)diazagermol-2-ylidene (1). In addition, the X-ray crystal structures of the previously synthesised 1,3-bis(2,4,6-trimethylphenyl)diazagermol-2-ylidene (2) and 1,3-bis(2,6-diisopropylphenyl)diazagermol-2-ylidene (3) are also reported. The discrete molecular structures of compounds 1 to 3 are comparable, with Ge-N bond lengths in the range 1.835-1.875 Å, while the N-Ge-N bond angles range between 83.6 and 85.2°. Compound 2 was compared to the analogous N-heterocyclic carbene species, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes). The major geometrical difference observed, as expected, was the bond angle around the divalent group 14 atom. The N-Ge-N bond angle was 83.6° for compound 2 versus the N-C-N bond angle of 101.4° for IMes. The Sn equivalent of (1), 1,3-bis(2,6-dimethylphenyl)diazastannol-2-ylidene (4), has also been synthesised and its crystal structure is reported here. In order to test their suitability as ligands, compounds 1 to 3 were reacted with a wide range of transition metal complexes. No NHGes containing metal complexes were observed. In all cases the NHGe either degraded or gave no reaction

Methyl 2-amino-5-iso­propyl-1,3-thia­zole-4-carboxyl­ate

The title compound, C8H12N2O2S, forms a supramolecular network based on N-HN hydrogen-bonded centrosymmetric dimers that are linked in turn by N-HO contacts

Diisopropylamide and TMP turbo-grignard reagents : a structural rationale for their contrasting reactivities

A neutral dimeric molecule in crystal form, the diisopropylamido turbo-Grignard reagent "(iPr2N)MgCl⋅LiCl" (see structure; blue N, red O, green Mg, yellow Cl, black C) separates into several charged ate species in dynamic exchange with each other in THF solution as determined by a combination of EXSY and DOSY NMR studies

Multistep self-assembly of heteroleptic magnesium and sodium-magnesium benzamidinate complexes

Reaction of the magnesium bis-alkyl Mg(CH2SiMe3)(2) and the sodium amide NaHMDS (where HMDS = N(SiMe3)(2)) with benzonitrile yields the homometallic heteroleptic complex [PhC(NSiMe3)(2)Mg{mu-NC(CH2SiMe3)Ph}](2) (1). It appears that at least six independent reactions must have occurred in this one-pot reaction to arrive at this mixed benzamidinate ketimido product. Two benzonitrile solvated derivatives of Mg(CH2SiMe3)(2) (5a and 5b) have been synthesized, with 5a crystallographically characterized as a centrosymmetric (MgC)(2) cyclodimer. When, the components of 5a are allowed to react for longer, partial addition of the Mg-alkyl unit across the C N triple bond occurs to yield the trimeric species (Me3SiCH2)(2)Mg-3[mu-N=C(CH2SiMe3)Ph](4)center dot 2N CPh (6), with bridging ketimido groups and terminal alkyl groups. Finally, using the same starting materials as that which produced 1, but altering their order of addition, a magnesium bis-alkyl unit is inserted into the Na-N bonds of a benzamidinate species to yield a new sodium magnesiate complex, PhC(NSiMe3)(2)Mg(mu-CH2SiMe3)(2)Na center dot 2TMEDA (7). The formation of 7 represents a novel (insertion) route to mixed-metal species of this kind and is the first Such example to contain a bidentate terminal anion attached to the divalent metal center. All new species are characterized by H-1 and C-13 NMR spectroscopy and where appropriate by IR spectroscopy. The solid-state structures of complexes 1, 5a, and 7 have also been determined and are disclosed within

Formation of a nonanuclear copper(II) cluster with 3,5-dimethylpyrazolate starting from an NHC complex of copper(I) chloride

The complete nonanuclear cluster in bis[1,3-bis(2,6-dimethylphenyl)imidazolium] di--chlorido-tetrachloridooctakis(-3,5-dimethylpyrazolato)hexa-3- hydroxido-nonacopper(II) chloroform disolvate, [HIXy]2[Cu9(-pz*)8(3- OH)6(2-Cl)2Cl4]2CHCl3 or (C19H21N2)2[Cu9(C5H7N2)8Cl6(OH)6]2CHCl3, where pz* is the 3,5-dimethylpyrazolyl anion, C5H7N2 , and HIXy is the 1,3- bis(2,6-dimethylphenyl)imidazolium cation, C19H21N2 +, is generated by a crystallographic centre of symmetry with a square-planar CuII ion bound to four 3-OH ions lying on the inversion centre. Of the four remaining unique CuII atoms, three adopt CuN2O2Cl square-pyramidal coordination geometries with the chloride ion in the apical position and one has a distorted CuN2OCl tetrahedral geometry. The dianionic nonanuclear core can be described as a 24-membered [CuNN]8 ring that contains a Cu9O6Cl6 core. The cluster features three intramolecular O—H Cl hydrogen bonds. In the crystal, weak C— H N and C—H Cl interactions link the components. Polynuclear paramagnetic clusters of this type are of considerable interest due to their relevance to both the bioinorganic and single-molecule magnets research fields

2-Amino­ethanaminium iodide

The title salt, [NH3CH2CH2NH2]+·I−, has an array structure based on strong inter­molecular N—H⋯N hydrogen bonding formed between the ammonium and amine groups of adjacent cations. This inter­action gives a helical chain of cations that runs parallel to the b axis. The four remaining NH group H atoms all form hydrogen bonds to the iodide anion, and these iodide anions lie in channels parallel to the cation–cation chains

The hydrochloride and hydrobromide salt forms of (S)-amphetamine

(S)-Amphetamine hydrochloride, C9H14ClN, has a Z′ = 6 structure with six independent cation, anion pairs. That these are indeed crystallographically independent is supported by different packing orientations of the cations and by observation of a wide range of cation conformations generated by rotation about the phenyl–CH2 bond. The supramolecular contacts about the anions also differ such that both a wide variation in the geometry of the three N–H···Cl hydrogen bonds formed by each chloride anion and differences in C–H···Cl contacts are apparent. (S)-Amphetamine hydrobromide, C9H14BrN, is broadly similar to the chloride in terms of cation conformation, the existance of three N–H···X hydrogen bond contacts per anion and the overall 2 dimensional hydrogen bonded sheet motif. However, only the chloride structure features organic bilayers and Z′ > 1

Trans-metal-trapping meets FLP chemistry : Ga(CH2SiMe3)3 induced C-H functionalizations

Merging two topical themes in Main Group chemistry, namely cooperative bimetallics and FLP activity, this Forum Article focuses on the cooperativity-induced outcomes observed when the tris(alkyl)gallium compound GaR3 (R= CH2SiMe3) is paired with lithium amide LiTMP (TMP=2,2,6,6-tetramethylpiperidide) or the sterically hindered NHC ItBu (ItBu = 1,3-bis(tert-butyl)imidazol-2-ylidene). Drawing together some previously published work with new results, unique tandem reactivities are presented which are driven by the steric mismatch between the individual reagents of these multicomponent reagents. Thus the LiTMP/GaR3 combination, which on its own fails to form a co-complex, functions as a highly regioselective base (LiTMP)-trap (GaR3) partnership for metalation of N-heterocycles such as diazines, 1,3 benzo-azoles and 2-picoline in a trans-metal-trapping (TMT) process that stabilizes the emerging sensitive carbanions. Taking advantage of related steric incompatibility, a novel monometallic FLP system pairing GaR3 with ItBu has been developed for activation of carbonyl compounds (via C=O insertion) and other molecules with acidic hydrogen atoms such as phenol and phenylacetylene. Shedding new light on how these non-cocomplexing partnerships operate and showcasing the potential of Ga reagents to engage in metalation reactions or FLP activations, areas where the use of this Group 13 metal is scant, this Forum Article aims to stimulate more interest and activity towards the advancement of organogallium chemistry

Tetradentate Schiff base beryllium complexes

The structure of (BeSalen)2 is reported. The incompatibility of the geometry of the beryllium with the inflexibility of the Salen ligand gives rise to a rare dimeric bis-didentate motif