Synthesis of 1,2-diaminotruxinic δ-cyclobutanes by BF-controlled [2 + 2]-photocycloaddition of 5(4)-oxazolones and stereoselective expansion of δ-cyclobutanes to give highly substituted pyrrolidine-2,5-dicarboxylates.

The irradiation of ()-4-arylidene-5(4)-oxazolones 1a-1u with blue light (465 nm) in the presence of the photosensitizer [Ru(bpy)](BF) (2.5 mol%) and the Lewis acid BF·OEt (2 equiv.) in deoxygenated methanol at room temperature affords the corresponding 1,2-diaminotruxinic cyclobutane bis-amino esters 2a-2u stereoselectively as the δ-isomer.

Chemistry of a Nitrosyl Ligand κ:η-Bridging a Ditungsten Center: Rearrangement and N-O Bond Cleavage Reactions.

The novel nitrosyl-bridged complex [WCp(μ-PBu)(μ-κ:η-NO)(CO)(NO)](BAr) [Ar = 3,5-CH(CF)] was prepared in a multistep procedure starting from the hydride [WCp(μ-H)(μ-PBu)(CO)] and involving the new complexes [WCp(μ-PBu)(CO)](BF), [WCp(μ-PBu)(CO)(NO)](BAr), and [W(μ-κ:η-CH)Cp(μ-PBu)(CO)(NO)] as intermediates, which follow from reactions with HBF·OEt, NO, and MeNO·2HO, respectively. The nitrosyl-bridged cation easily added chloride upon reaction with [N(PPh)]Cl, with concomitant NO rearrangement into the terminal coordination mode, to give [WClCp(μ-PBu)(CO)(NO)], and underwent N-O and W-W bond cleavages upon the addition of CNBu to give the mononuclear phosphinoimido complex [WCp(NPBu)(CNBu)](BAr). Another N-O bond cleavage was induced upon photochemical decarbonylation at 243 K, which gave the oxo- and phosphinito-bridged nitrido complex [WCp(N)(μ-O)(μ-OPBu)(NO)](BAr), likely resulting from a N-O bond cleavage step following decarbonylation.

Water and 2,2,6,6-tetra-methyl-piperidine: an odd couple make a solid match.

Commentary is given on a paper [Butler (2022). , , 364-369] reporting the crystallization of two room-temperature liquids, water and 2,2,6,6-tetra-methyl-piperidine, to form a crystalline solid with a water-lined channel potentially capable of proton transport.

Stability of Ag towards Halides in Organosilver(III) Complexes.

The involvement of silver in two-electron Ag /Ag processes is currently emerging. However, the range of stability of the required and uncommon Ag species is virtually unknown. Here, the stability of Ag towards the whole set of halide ligands in the organosilver(III) complex frame [(CF ) AgX] (X=F, Cl, Br, I, At) is theoretically analyzed.

Building C(sp ) Molecular Complexity on 2,2'-Bipyridine and 1,10-Phenanthroline in Rhenium Tricarbonyl Complexes.

The reactions of [Re(N-N)(CO) (PMe )]OTf (N-N=2,2'-bipyridine, bipy; 1,10-phenanthroline, phen) compounds with tBuLi and with LiHBEt have been explored. Addition to the N-N chelate took place with different site-selectivity depending on both chelate and nucleophile. Thus, with tBuLi, an unprecedented addition to C5 of bipy, a regiochemistry not accessible for free bipy, was obtained, whereas coordinated phen underwent tBuLi addition to C2 and C4.

Tetra--butyl-ammonium orotate monohydrate: knowledge-based comparison of the results of accurate and lower-resolution analyses and a non-routine disorder refinement.

The title hydrated mol-ecular salt (systematic name: tetra--butyl-ammonium 2,6-dioxo-1,2,3,6-tetra-hydro-pyrimidine-4-carboxyl-ate monohydrate), CHN·CHNO ·HO, crystallizes with N-H⋯O and O-H⋯O hydrogen-bonded double-stranded anti-parallel ribbons consisting of the hydro-philic orotate monoanions and water mol-ecules, separated by the bulky hydro-phobic cations. The hydro-phobic and hydro-philic regions of the structure are joined by weaker non-classical C-H⋯O hydrogen bonds. An accurate structure analysis conducted at = 100 K is compared to a lower-resolution less accurate determination using data measured at = 295 K.

Slow magnetic relaxation in Ni-Ln (Ln = Ce, Gd, Dy) dinuclear complexes.

Three new isomorphous complexes [Ni(o-van-en)LnCl(HO)] [H(o-van-en) = N,N'-ethylene-bis(3-methoxysalicylaldiminate; Ln = Ce (1), Gd (2), Dy (3)] were prepared by a stepwise reaction using mild conditions and were structurally characterised as dinuclear molecules in which Ni and Ln are coordinated by the compartmental Schiff base ligand (o-van-en) and doubly bridged by O atoms. While the nickel(ii) centre is diamagnetic within the NO square-planar coordination of the Schiff base ligand, the lanthanide atoms are octa-coordinated to give an {LnClO} chromophore with a fac-arrangement of the chlorido ligands. AC magnetic measurements revealed that all three complexes, including the nominally isotropic Gd(iii) system, show field induced slow magnetic relaxation with two or three relaxation channels: at T = 1.

Polymorphism of the dinuclear Co-Schiff base complex [Co(o-van-en)]·4CHCN (o-van-en is a salen-type ligand).

Reactions of Co(OH) with the Schiff base bis(2-hydroxy-3-methoxybenzylidene)ethylenediamine, denoted H(o-van-en), under different conditions yielded the previously reported complex aqua[bis(3-methoxy-2-oxidobenzylidene)ethylenediamine]cobalt(II), [Co(CHNO)(HO)], 1, under anaerobic conditions and two polymorphs of [μ-bis(3-methoxy-2-oxidobenzylidene)ethylenediamine]bis{[bis(3-methoxy-2-oxidobenzylidene)ethylenediamine]cobalt(III)} acetonitrile tetrasolvate, [Co(CHNO)]·4CHCN, i.e. monoclinic 2 and triclinic 3, in the presence of air.

Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands.

Trinuclear cobalt paddlewheel complexes, [Co3(dpa)4X2] (dpa = the anion of 2,2'-dipyridylamine, X = Cl-, Br-, -NCS-, -CN-, (NC)2N-), are known to demonstrate a thermally-induced spin-crossover (SCO). Despite a wealth of structural and magnetic information about such complexes, the role of the axial ligand on the characteristic SCO temperature (T1/2) remains ambiguous. The situation is complicated by the observation that the solid state geometry of the complexes, symmetric or unsymmetric, with respect to the central cobalt ion, also appears to influence the SCO behavior.

Exceptionally slow magnetic relaxation in cobalt(ii) benzoate trihydrate.

Cobalt(ii) benzoate trihydrate prepared by the reaction of CoCO with benzoic acid (HBz) in boiling water followed by crystallization has been structurally characterized as a chain-like system with the formula unit [Co(Bz)(HO)]Bz·HO where the Co(ii) atoms are triply linked by one bridging syn-syn benzoato (Bz) and two aqua ligands; additional benzoate counter ions and solvate water molecules are present in the crystal structure. DC magnetic measurements reveal a sizable exchange coupling of a ferromagnetic nature between the Co(ii) atoms. At T = 5.

Crystalline transformers: more within than meets the eye.

Studies of phase transitions in molecular crystals are becoming more commonplace as improvements in instrumentation and technique enable more efficient exploration of the behavior of samples with varying external conditions, usually temperature. This scientific commentary provides contextual background on this type of study, with reference to an article on transformations in a ferrocenyl-acetylide-gold(I) complex [Makal (2018). Acta Cryst.

A phase transition caught in mid-course: independent and concomitant analyses of the monoclinic and triclinic structures of (BuN)[Co(orotate)(bipy)]·3HO.

The preparation and characterization of the BuN salts of two bis-orotate(2-) complexes of cobalt, namely bis(tetra-n-butylammonium) diaquabis(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κN,O)cobalt(II) 1.8-hydrate, (CHN)[Co(CHNO)(HO)]·1.8HO, (1), and tetra-n-butylammonium (2,2'-bipyridine-κN,N')bis(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κN,O)cobalt(III) trihydrate, (CHN)[Co(CHNO)(CHN)]·3HO, (2), are reported.

(CF ) Au as a Highly Acidic Organogold(III) Fragment.

The Lewis acidity of perfluorinated trimethylgold (CF ) Au was assessed by theoretical and experimental methods. It was found that the (CF ) Au unit is much more acidic than its nonfluorinated analogue (CH ) Au, and probably sets the upper limit of the acidity scale for neutral organogold(III) species R Au. The significant acidity increase on fluorination is in line with the CF group being more electron-withdrawing than CH .

A hexanuclear gold carbonyl cluster.

The hexanuclear gold carbonyl cluster [PPh][Au(CF)Br(CO)] () has been obtained by spontaneous self-assembly of the following independent units: CFAuCO () and [PPh][Br(AuCF)] (). The -Au aggregate , in which the components are held together by unassisted, fairly strong aurophilic interactions (Au···Au ∼310 pm), exhibits a cyclohexane-like arrangement with chair conformation. These aurophilic interactions also result in significant (CO) lowering: from 2194 cm in the separate component to 2171 cm in the mixed aggregate .

Synthesis, crystal structure and magnetic properties of (acetato-κ²O,O')bis(5,5'-dimethyl-2,2'-bipyridine-κ²N,N')nickel(II) perchlorate monohydrate.

The title hydrated ionic complex, [Ni(CH3COO)(C12H12N2)2]ClO4·H2O or [Ni(ac)(5,5'-dmbpy)2]ClO4·H2O (where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate-5,5'-dmbpy-KClO4 system. Within the complex cation, the Ni(II) atom is hexacoordinated by two chelating 5,5'-dmbpy ligands and one chelating ac ligand. The mean Ni-N and Ni-O bond lengths are 2.

Fitting the pieces of the puzzle: the δ bond.

The development of our understanding of the δ bond and its role in quadruple metal-metal bonding is described in terms of the conceptual advances and experimental and theoretical results achieved through a 50-year period beginning with the seminal report by Cotton and co-workers in 1964. The work behind the original discovery is described, along with the qualitative orbital description of the components of the quadruple bond. The effect of torsion about the metal-metal axis on the metal-metal bond length is described, together with the conclusion that this accords with a progressive loss of the δ component of the metal-metal bond.

A discrete neutral transition-metal citrate cubane with an M₄O₄ core; coordinative versatility of the [M(II)₄(citrate)₄]⁸⁻ fragment.

The neutral cluster [Mn(II)8(citrate)4(H2O)18] is formed by the [M4(citrate)4](8-) fragment, with an Mn4O4 cubane core, which bonds four peripheral aquomanganese units--two [Mn(H2O)4](2+) and two [Mn(H2O)5](2+)--through a total of six metal-ligand bonds, giving a discrete neutral compound. The compound presents a unique coordination mode in which the citrate cubane acts as a chelate to each of the two peripheral [Mn(H2O)4](2+) (tetra-aquo) units. A detailed analysis of the central and peripheral geometries is given in terms of the tetrahedral distortions of key structural features.

Synthesis, characterization and crystal structure of the new pentahydrate of bis(2,2'-bipyridine-κ(2)N,N')(oxalato-κ(2)O(1),O(2))nickel(II).

The reaction of NiCl2, K2C2O4·H2O and 2,2'-bipyridine (bpy) in water-ethanol solution at 281 K yields light-purple needles of the new pentahydrate of bis(2,2'-bipyridine)oxalatonickel(II), [Ni(C2O4)(C10H8N2)2]·5H2O or [Ni(ox)(bpy)2]·5H2O, while at room temperature, deep-pink prisms of the previously reported tetrahydrate [Ni(ox)(bpy)2]·4H2O [Román, Luque, Guzmán-Miralles & Beitia (1995), Polyhedron, 14, 2863-2869] were gathered. The asymmetric unit in the crystal structure of the new pentahydrate incorporates the discrete molecular complex [Ni(ox)(bpy)2] and five solvent water molecules. Within the complex molecule, all three ligands are bonded as chelates.

Gold(I) and gold(III) trifluoromethyl derivatives.

Trifluoromethylation of AuCl3 by using the Me3 SiCF3 /CsF system in THF and in the presence of [PPh4 ]Br proceeds with partial reduction, yielding a mixture of [PPh4 ][Au(I) (CF3 )2 ] (1') and [PPh4 ][Au(III) (CF3 )4 ] (2') that can be adequately separated. An efficient method for the high-yield synthesis of 1' is also described. The molecular geometries of the homoleptic anions [Au(I) (CF3 )2 ](-) and [Au(III) (CF3 )4 ](-) in their salts 1' and [NBu4 ][Au(III) (CF3 )4 ] (2) have been established by X-ray diffraction methods.

Crystal structure and thermal properties of a square-planar Ni(II) complex of cyanide and a tricyclic bis-amidine ligand formed in situ under solvothermal conditions.

The reaction of N(1),N(1')-(ethane-1,2-diyl)bis(propane-1,3-diamine) (bapen), K2[Ni(CN)4]·H2O and dimethylformamide in the presence of Gd(NO3)3·6H2O under solvothermal conditions yielded yellow crystals of dicyanido(2,3,4,6,7,9,10,11-octahydropyrimido[2',1':3,4]pyrazino[1,2-a]pyrimidine)nickel(II) hemihydrate, [Ni(CN)2(C10H16N4)]·0.5H2O, (I), the crystal structure of which is composed of [Ni(CN)2(pdpm)] molecules (pdpm is 2,3,4,6,7,9,10,11-octahydropyrimido[2',1':3,4]pyrazino[1,2-a]pyrimidine) on general positions linked by O-H···N hydrogen bonds to water molecules located on twofold axes. This structural unit is further linked by nonclassical C-H···N interactions to form a warped two-dimensional net perpendicular to the unit-cell b axis.

Luminescent di- and polynuclear organometallic gold(I)-metal (Au2, {Au2Ag}n and {Au2Cu}n) compounds containing bidentate phosphanes as active antimicrobial agents.

The reaction of new dinuclear gold(I) organometallic complexes containing mesityl ligands and bridging bidentate phosphanes [Au(2)(mes)(2)(μ-LL)] (LL=dppe: 1,2-bis(diphenylphosphano)ethane 1a, and water-soluble dppy: 1,2-bis(di-3-pyridylphosphano)ethane 1b) with Ag(+) and Cu(+) lead to the formation of a family of heterometallic clusters with mesityl bridging ligands of the general formula [Au(2)M(μ-mes)(2) (μ-LL)][A] (M=Ag, A=ClO(4)(-), LL=dppe 2a, dppy 2b; M=Ag, A=SO(3)CF(3)(-), LL=dppe 3a, dppy 3b; M=Cu, A=PF(6)(-), LL=dppe 4a, dppy 4b). The new compounds were characterized by different spectroscopic techniques and mass spectrometry The crystal structures of [Au(2)(mes)(2)(μ-dppy)] (1b) and [Au(2)Ag(μ-mes)(2)(μ-dppe)][SO(3)CF(3)] (3a) were determined by a single-crystal X-ray diffraction study. 3a in solid state is not a cyclic trinuclear Au(2)Ag derivative but it gives an open polymeric structure instead, with the {Au(2)(μ-dppe)} fragments "linked" by {Ag(μ-mes)(2)} units.

A square two-dimensional polymer of cobalt citrate cubanes.

The structure of the title complex, poly[dicaesium(I) hexaaquacobalt(II) [octaaquatetra-μ-citrato-hexacobalt(II)] dodecahydrate], {Cs(2)[Co(H(2)O)(6)][Co(6)(C(6)H(4)O(7))(4)(H(2)O)(8)]·12H(2)O}(n), at 100 (1) K is formed by layers of a square two-dimensional polymer composed of Co(II) citrate cubanes bridged by magnetically active six-coordinate Co(II) cations. The polymer has plane symmetry p4mm in the c-axis projection. The cubanes reside on sites of crystallographic symmetry 4, while the bridging Co(II) centres lie on twofold axes.