Substrate-Mediated Deactivation of a Ru(P\u3csup\u3et\u3c/sup\u3e\u3csup\u3eBu\u3c/sup\u3e2N\u3csup\u3eBn\u3c/sup\u3e2) Cooperative Complex

Ligand design for metal-ligand cooperative (MLC) catalysis is inherently more complex than that for traditional non-cooperative ligands. The basicity, sterics and structure of the acid/base group in MLC proton-transfer (PT) complexes, for instance, undoubtedly influence catalyst performance. Herein, we evaluate the highly tunable PR2NR′2 (1,5-R′-3,7-R-1,5-diaza-3,7-diphosphacyclooctane) ligand family for the first time in an organic transformation. With [Ru(Cp)(PtBu2NBn2)(MeCN)][PF6] as the catalyst, no turnover was observed in the anti-Markovnikov hydration of alkynes, a known PT MLC reaction. Treatment of the cooperative complex with phenylacetylene affords a vinylammonium product in which the pendant nitrogen atom of the PtBu2NBn2 ligand forms a Lewis acid-base adduct with the alpha-carbon atom of the vinylidene intermediate. Characterization by X-ray crystallography and NMR spectroscopy conclusively assign this structure in both the solid and the solution state. The adduct formation is irreversible, and the adduct is characterized as a catalyst deactivation product. Snapping Shut: The PR2NR′2 ligand family (R and R′ are removed for clarity in the graphic) open the door for easily tuned catalysts for cooperative organic transformations. However, the ligand swings toward the vinylidene, forming a stable (and catalytically inactive) Lewis acid-base adduct. (□ = open coordination site

Tetra­kis(acetonitrile-κN)lithium hexa­fluoridophosphate acetonitrile monosolvate

In the title compound, [Li(CH3CN)4]PF6·CH3CN, the asymmetric unit consists of three independent tetra­hedral [Li(CH3CN)4]+ cations, three uncoordinated PF6 − anions and three uncoordinated CH3CN solvent mol­ecules. The three anions are disordered over two sites through a rotation along one of the F—P—F axes. The relative occupancies of the two sites for the F atoms are 0.643 (16):0.357 (16), 0.677 (10):0.323 (10) and 0.723 (13):0.277 (13). The crystal used was a racemic twin, with approximately equal twin components

Selective Oxygen Atom Insertion into an Aryl-Palladium Bond

The chemistry of a palladium(II) complex containing both an alkyl- and an aryl-palladium bond is reported. The reaction of [Pd(CH2CMe2C6H4)(MesN=CHCH=NMes)] with bromine or iodine leads to reductive elimination of 1,1-dimethylcyclobutabenzene with formation of [PdX2(MesN=CHCH=NMes)] (X = Br, I). However, the reaction with hydrogen peroxide gives [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] by overall oxygen atom insertion into the aryl-palladium rather than the alkyl-palladium bond. This complex [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] reacts with bromine, iodine, or hydrogen peroxide to give 3,3-dimethyl-2,3-dihydrobenzofuran and the corresponding complex [PdX2(MesN=CHCH=NMes)]. The mechanisms of reaction and basis for selectivity are discussed. The results support the view that oxygen atom insertion is a mechanistically viable pathway for selective catalytic oxidation of hydrocarbons by the green oxidant hydrogen peroxide

Lithium bis­(2-methyl­lactato)borate monohydrate

The title compound {systematic name: poly[[aqua­lithium]-μ-3,3,8,8-tetra­methyl-1,4,6,9-tetra­oxa-5λ4-borataspiro­[4.4]nonane-2,7-dione]}, [Li(C8H12BO6)(H2O)]n (LiBMLB), forms a 12-membered macrocycle, which lies across a crystallographic inversion center. The lithium cations are pseudo-tetra­hedrally coordinated by three methyl­lactate ligands and a water mol­ecule. The asymmetric units couple across crystallographic inversion centers, forming the 12-membered macrocycles. These macrocycles, in turn, cross-link through the Li+ cations, forming an infinite polymeric structure in two dimensions parallel to (101)

Catalytic Acceptorless Dehydrogenation of Amines with Ru(P\u3csup\u3eR\u3c/sup\u3e2N\u3csup\u3eR′\u3c/sup\u3e2) and Ru(dppp) Complexes

[Ru(Cp)(PPh2NBn2)(MeCN)]PF6 (1; PPh2NBn2 = 1,5-benzyl-3,7-phenyl-1,5-diaza-3,7-diphosphacyclooctane) and [Ru(Cp)(dppp)(MeCN)]PF6 (2; dppp = 1,3-bis(diphenylphosphino)propane) are both active toward the acceptorless dehydrogenation of benzylamine (BnNH2) and N-heterocycles. The two catalysts have similar activities but different selectivities for dehydrogenation products. Independent synthesis of a [Ru(Cp)(PPh2NBn2)(NH2Bn)]PF6 adduct (3) reveals the presence of a hydrogen bond between the bound amine and the pendent base of the PPh2NBn2 ligand. Preliminary mechanistic studies reveal that the benzylamine adduct is not an on-cycle catalyst intermediate

Pincer-plus-one ligands in self-assembly with palladium(ii): a molecular square and a molecular tetrahedron

The combination of a palladium(ii) precursor with a diimine-phenol ligand and an oxidant (H2O2 or O2) under different conditions has, serendipitously, given both a molecular square and a molecular tetrahedron by self-assembly of building blocks comprising palladium(ii) centres coordinated to the oxidised forms of the ligand

Synthesis and Characterization of a Family of Air-Stable Ferrocene- and Ruthenocene-Containing Primary, Secondary, and Tertiary Phosphines

The synthesis and characterization of a family of air-stable primary, secondary, and tertiary phosphines containing all possible combinations of ethylferrocene and ethylruthenocene substituents are reported. Each phosphine was characterized by 1H, 13C, and 31P NMR spectroscopy, IR and UV-vis absorption spectroscopy, mass spectrometry, and elemental analysis. With the exception of primary ethylruthenocene phosphine 8a, all of the title compounds have been studied by single crystal X-ray crystallography. Ferrocene-containing phosphines showed maximum absorption at wavelengths of ca. 440 nm and qualitatively reversible oxidation waves in their cyclic voltammograms with intensities scaling to the number of ferrocene units present. The average metal-cyclopentadienyl centroid distances observed for ferrocene-containing phosphines were shorter than those of ruthenocene-containing phosphines, which also had maximum absorption wavelengths of ca. 320 nm and underwent irreversible electrochemical oxidation. Phosphines containing both ethylferrocene and ethylruthenocene substituents displayed properties consistent with the presence of both metallocene types

High serum immunoglobulin g and m levels predict freedom from adverse cardiovascular events in hypertension: a nested case-control substudy of the Anglo-Scandinavian cardiac outcomes trial

Aims: We aimed to determine whether the levels of total serum IgM and IgG, together with specific antibodies against malondialdehyde-conjugated low-density lipoprotein (MDA-LDL), can improve cardiovascular risk discrimination. Methods and Results: The Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) randomized 9098 patients in the UK and Ireland into the Blood Pressure-Lowering Arm. 485 patients that had cardiovascular (CV) events over 5.5 years were age and sex matched with 1367 controls. Higher baseline total serum IgG, and to a lesser extent IgM, were associated with decreased risk of CV events (IgG odds ratio (OR) per one standard deviation (SD) 0.80 [95% confidence interval, CI 0.72,0.89], p < 0.0001; IgM 0.83[0.75,0.93], p = 0.001), and particularly events due to coronary heart disease (CHD) (IgG OR 0.66 (0.57,0.76); p < 0.0001, IgM OR 0.81 (0.71,0.93); p = 0.002). The association persisted after adjustment for a basic model with variables in the Framingham Risk Score (FRS) as well as following inclusion of C-reactive protein (CRP) and N-terminal pro-B-type natriuretic peptide (NtProBNP). IgG and IgM antibodies against MDA-LDL were also associated with CV events but their significance was lost following adjustment for total serum IgG and IgM respectively. The area under the receiver operator curve for CV events was improved from the basic risk model when adding in total serum IgG, and there was improvement in continuous and categorical net reclassification (17.6% and 7.5% respectively) as well as in the integrated discrimination index. Conclusion: High total serum IgG levels are an independent predictor of freedom from adverse cardiovascular events, particularly those attributed to CHD, in patients with hypertension

A strongly Lewis-acidic and fluorescent borenium cation supported by a tridentate formazanate ligand

Lewis acids are highly sought after for their applications in sensing, small-molecule activation, and catalysis. When combined with π-conjugated molecular frameworks, Lewis acids with unique optoelectronic properties can be realized. Here, we use a tridentate formazanate ligand to create a planar, redox-active, fluorescent, and strongly Lewis-acidic borenium cation. We also demonstrate that this compound can act as a colourimetric probe for reactivity

Poly[diacetonitrile­[μ3-difluoro­(oxalato)borato]sodium]

The title compound, [Na(C2BF2O4)(CH3CN)2]n, forms infinite two-dimensional layers running parallel to (010). The layers lie across crystallographic mirror planes at y = 1/4 and 3/4. The Na, B and two F atoms reside on these mirror planes. The Na+ cations are six-coordinate. Two equatorial coordination positions are occupied by acetonitrile mol­ecules. The other two equatorial coordination sites are occupied by the chelating O atoms from the difluoro­(oxalato)borate anion (DFOB−). The axial coordination sites are occupied by two F atoms from two different DFOB− anions