Synthesis and Characterisation of WVI Complexes of Phosphane Oxide Ligands, [WO2X2(OPR3)2] (X = F, Cl or Br; R = Me or Ph), and of the [MoO2F2(OPR3)2]

Tetrel bond in the triphenyltin(IV) chloride-cyclo-hexyl-diphenyl-phosphane oxide (1/1) cocrystal

The single-crystal X-ray diffraction structure of the title compound, [SnCl(C6H5)3]·C18H21OP, is reported. The 1:1 cocrystal features a short and directional tetrel bond between tin and oxygen. The tin-oxygen distance is 2.346 (4) Å, representing 62% of the sum of the van der Waals radii of Sn and O. The Cl-Sn⋯O angle is 174.0 (1)° and this nearly linear arrangement is consistent with a tetrel bond formed via a σ-hole opposite the tin-chlorine covalent bond. Some weak C-H⋯Cl inter-actions are noted between adjacent mol-ecules.

Group 3 metal trihalide complexes with neutral N-donor ligands - exploring their affinity towards fluoride

Fluorination of [ScCl3(Me3-tacn)] (Me3-tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) and [ScCl3(BnMe2-tacn)] (BnMe2-tacn = 1,4-dimethyl-7-benzyl-1,4,7-triazacyclononane) by Cl/F exchange with 3 mol. equiv. of anhydrous [NMe4]F in CH3CN solution yields the corresponding [ScF3(R3-tacn)] (R3 = Me3 or BnMe2). These are the first examples of scandium fluoride complexes containing neutral co-ligands. The fluorination occurs stepwise, and using a deficit of [NMe4]F produced [ScF2Cl(Me3-tacn)]. Attempts to fluorinate [YCl3(Me3-tacn)], [YI3(Me3-tacn)], [LaCl3(Me3-tacn)(OH2)] or [MCl3(terpy)] (M = Sc, Y or La; terpy = 2,2':6'2''-terpyridyl) using a similar method were unsuccessful, due to the Cl/F exchange being accompanied by loss of the neutral ligand from the metal centre. Fluorination of [ScCl3(Me3-tacn)] or [ScCl3(terpy)] with Me3SnF was also successful. The products were identified as the very unusual heterobimetallic [Sc(Me3-tacn)F2(μ-F)SnMe3Cl] and [Sc(terpy)F(μ-F)2(SnMe3Cl)2], in which the Me3SnCl formed in the reaction behaves as a weak Lewis acid towards the scandium fluoride complex, linked by Sc-F-Sn bridges. [Sc(terpy)F(μ-F)2(SnMe3Cl)2] decomposes irreversibly in solution but, whilst multinuclear NMR data show that [Sc(Me3-tacn)F2(μ-F)SnMe3Cl] is dissociated into the [ScF3(Me3-tacn)] and Me3SnCl in CH3CN solution, the bimetallic complex reforms upon evaporation of the solvent. The new scandium fluoride complexes and the chloride precursors have been characterised by microanalysis, IR and multinuclear NMR (1H, 19F, 45Sc) spectroscopy as appropriate. X-ray crystal structures provide unambiguous evidence for the identities of [Sc(Me3-tacn)F2(μ-F)SnMe3Cl], [ScF2Cl(Me3-tacn)], [YI3(Me3-tacn)], [{YI2(Me3-tacn)}2(μ-O)], [ScCl3(terpy)], [YCl3(terpy)(OH2)], and [{La(terpy)(OH2)Cl2}2(μ-Cl)2]. Once formed, the [ScF3(R3-tacn)] complexes are stable in water and unaffected by a ten-fold excess of Cl- or MeCO2-, although they are immediately decomposed by excess F-. The potential use of [ScF3(R3-tacn)] type complexes as platforms for 18F PET (positron emission tomography) radiopharmaceuticals is briefly discussed. Attempts to use the Group 3 fluoride "hydrates", MF3·xH2O, as precursors were unsuccessful; no reaction with R3-tacn or terpy occurred either on reflux in CH3CN or under hydrothermal conditions (H2O, 180° C, 15 h). PXRD data showed that these "hydrates" actually contain the anhydrous metal trifluorides with small amounts of surface or interstitial water.

Second-generation hexavalent molybdenum oxo-amidinate precursors for atomic layer deposition

The synthesis and characterization of molybdenum oxo-amidinate ALD precursors MoO₂(R₂AMD)₂[AMD =N,N′-di-R-acetamidinate; R = Cy (2; cyclohexyl) andⁱPr (3)] is reported.

Synthesis of a highly reactive form of WO2Cl2, its conversion into nanocrystalline mono-hydrated WO3 and coordination compounds with tetramethylurea

A new form of WO₂Cl₂ was prepared from WCl₆. Conversion of WO₂Cl₂ into nanocrystalline WO₃·H₂O occurred upon air exposure at room temperature. The first coordination complexes of WO₂Cl₂ with an alkylurea are reported.

Dichlorodioxomolybdenum(vi) complexes bearing oxygen-donor ligands as olefin epoxidation catalysts

The complexes [MoO₂Cl₂(N,N-dimethylbenzamide)₂] and [MoO₂Cl₂(N,N′-diethyloxamide)] are active olefin epoxidation catalysts and can be easily recycled when using ionic liquid solvents.

Tungsten(VI) N-Heterocyclic Carbene Complexes: Synthetic, Structural, and Computational Study

The reaction of WOCl4 with 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (Idipp) leads to an orange solid whose spectroscopic data are consistent with the 1:1 adduct [WOCl4(Idipp)]. Computational studies at the DFT level further support this formulation. Exposure of this compound to the atmosphere results in rapid hydrolysis to various imidazolium salts. If air diffuses very slowly into solutions of [WOCl4(Idipp)], it also undergoes slow hydrolysis to form [WO2Cl2(Idipp)]. This has been crystallographically characterized and is the first five-coordinate, 1:1 adduct of WO2Cl2. This complex has also been subject to DFT calculations, and its metal-ligand bonding has been explored. The carbene-metal interaction is primarily σ-donor in nature. The mechanism of the hydrolysis has also been probed by computational methods, revealing a plausible, low-energy reaction pathway.

Tribenzyl-chlorido(triphenyl-phosphine oxide-κO)tin(IV)

In the title tribenzyl­chloridotin–triphenyl­phosphine adduct, [Sn(C₇H₇)₃Cl(C₁₈H₁₅OP)], the Sn^IV atom is in a trans-C₃SnClO trigonal–bipyramidal geometry and is displaced out of the C₃Sn girdle in the direction of the axial Cl atom by 0.112 (1) in one independent mol­ecule and by 0.167 (1) Å in the other. The phenyl ring of one of the six benzyl units was refined as equally disordered over two sets of sites.