Oxidation and chalcogenylative disproportionation of anionic phosphide ligands in yttrium complexes with elemental sulfur and selenium.

The oxidation and disproportionation of anionic phosphide ligands in yttrium complexes with elemental sulfur and selenium are reported. The mixed TpMe2/Cp supported yttrium phosphide complex TpMe2CpYPPh2(THF) (1) reacted with one equiv. of elemental S or Se in THF at room temperature to deliver two structurally characterized yttrium dithio- or monoseleno-phosphinates TpMe2CpYS2PPh2(THF) (2) and TpMe2CpYSePPh2(THF) (4Se), respectively. Further investigations showed that the yttrium thiophosphinate TpMe2CpYSPPh2(THF) (4S) can be isolated from the reactions of 2 and 1 or 1 and elemental S in a short reaction time. Moreover, after keeping 4S or 4Se in THF solution for some days, 2 or [(TpMe2)2Y]+[Se2PPh2]- (5) was obtained by a disproportionation process. The mechanism for the construction of the Ph2PE- and Ph2PE2- (E = S, Se) ligands has been discussed based on the in situ NMR experiments and some designed reactions.

An Yttrium Organic cyclo-P4 Complex and Its Selective Conversions.

The rare-earth-metal organic cyclo-P4 complex (LY·DMAP)2[1,2-R2- cyclo-P4] (2, L = N, N'-2,6-diisopropylphenyl-1,4-diazabutadiene, DMAP = 4- N, N'-dimethylpyridine, R = CH2C6H4NMe2-2) was synthesized by direct functionalization of P4 using the rare-earth-metal alkyl complex LYR(THF) (1) for the first time. Further investigations indicated that three selective conversions of the cyclo-P4 species have been realized by alkyl migration. Complex 2 was slowly transformed into a R2P-substituted cyclo-P3 cluster (LY·DMAP)2[ cyclo-P3PR2] (3) under heating conditions. The reaction of 2 with 1 equiv of KR gave the unsubstituted cyclo-P3 complex (LY·THF)2[ cyclo-P3]K (4) in quantitative yield, accompanied by the elimination of the organophosphorus compound PR3 (5). Treatment of 2 with HMPA afforded the structurally characterized Zintl-type P7 complex (LY·HMPA)3P7 (6). The formation of complexes 3, 4, and 6 revealed that unusual alkyl migrations in the polyphosphorus complexes occurred in these reactions, and the transformations from cyclo-P4 into cyclo-P3 also provided a new insight into the stepwise degradation of P4 using metal complexes.

A robust etb-type metal-organic framework showing polarity-exclusive adsorption of acetone over methanol for their azeotropic mixture.

We report a robust and rigid etb-type metal-organic framework, in which its pore surface is decorated with flexible ethoxyl groups. It shows unprecedentedly selective adsorption of acetone (E value of 0.355, kinetic diameter of 4.6 Å) over methanol (E value of 0.762, kinetic diameter of 3.6 Å) for their azeotropic mixture.

Reversing Conventional Reactivity of Mixed Oxo/Alkyl Rare-Earth Complexes: Non-Redox Oxygen Atom Transfer.

The preferential substitution of oxo ligands over alkyl ones of rare-earth complexes is commonly considered as "impossible" due to the high oxophilicity of metal centers. Now, it has been shown that simply assembling mixed methyl/oxo rare-earth complexes to a rigid trinuclear cluster framework cannot only enhance the activity of the Ln-oxo bond, but also protect the highly reactive Ln-alkyl bond, thus providing a previously unrecognized opportunity to selectively manipulate the oxo ligand in the presence of numerous reactive functionalities. Such trimetallic cluster has proved to be a suitable platform for developing the unprecedented non-redox rare-earth-mediated oxygen atom transfer from ketones to CS2 and PhNCS. Controlled experiments and computational studies shed light on the driving force for these reactions, emphasizing the importance of the sterical accessibility and multimetallic effect of the cluster framework in promoting reversal of reactivity of rare-earth oxo complexes.

Reversible Redox Activity in Multicomponent Metal-Organic Frameworks Constructed from Trinuclear Copper Pyrazolate Building Blocks.

Inorganic functionalization of metal-organic frameworks (MOFs), such as incorporation of multiple inorganic building blocks with distinct metals into one structure and further modulation of the metal charges, endows the porous materials with significant properties toward their applications in catalysis. In this work, by an exploration of the role of 4-pyrazolecarboxylic acid (H2PyC) in the formation of trinuclear copper pyrazolate as a metalloligand in situ, four new MOFs with multiple components in order were constructed through one-pot synthesis. This metalloligand strategy provides multicomponent MOFs with new topologies (tub for FDM-4 and tap for FDM-5) and is also compatible with a second organic linker for cooperative construction of complex MOFs (1,4-benzenedicarboxylic acid for FDM-6 and 2,6-naphthalenedicarboxylic acid for FDM-7). The component multiplicity of these MOFs originates from PyC's ability to separate Cu and Zn on the basis of their differentiated binding affinities toward pyrazolate and carboxylate. These MOFs feature reversible and facile redox transformations between CuI3(PyC)3 and CuII3(µ-OH)(PyC)3(OH)3 without altering the connecting geometries of the units, thus further contributing to the significant catalytic activities in the oxidation of CO and aromatic alcohols and the decomposition of H2O2. This study on programming multiple inorganic components into one framework and modulating their electronic structures is an example of functionalizing the inorganic units of MOFs with a high degree of control.

Fluorescent Gold Nanoclusters with Interlocked Staples and a Fully Thiolate-Bound Kernel.

The structural features that render gold nanoclusters intrinsically fluorescent are currently not well understood. To address this issue, highly fluorescent gold nanoclusters have to be synthesized, and their structures must be determined. We herein report the synthesis of three fluorescent Au24 (SR)20 nanoclusters (R=C2 H4 Ph, CH2 Ph, or CH2 C6 H4 (t) Bu). According to UV/Vis/NIR, differential pulse voltammetry (DPV), and X-ray absorption fine structure (XAFS) analysis, these three nanoclusters adopt similar structures that feature a bi-tetrahedral Au8 kernel protected by four tetrameric Au4 (SR)5 motifs. At least two structural features are responsible for the unusual fluorescence of the Au24 (SR)20 nanoclusters: Two pairs of interlocked Au4 (SR)5 staples reduce the vibration loss, and the interactions between the kernel and the thiolate motifs enhance electron transfer from the ligand to the kernel moiety through the Au-S bonds, thereby enhancing the fluorescence. This work provides some clarification of the structure-fluorescence relationship of such clusters.

HCl chemisorption-induced drastic magneto-structural transformation in a layered cobalt-phosphonotriazolate coordination polymer.

The chemisorption of gaseous HCl molecules in a two-dimensional coordination polymer results in subtle changes in its structure and instigates a drastic modification from antiferro- to ferromagnetic properties.

A Novel Small-Molecule Compound of Lithium Iodine and 3-Hydroxypropionitride as a Solid-State Electrolyte for Lithium-Air Batteries.

A novel small-molecule compound of lithium iodine and 3-hydroxypropionitrile (HPN) has been successfully synthesized. Our combined experimental and theoretical studies indicated that LiIHPN is a Li-ion conductor, which is utterly different from the I(-)-anion conductor of LiI(HPN)2 reported previously. Solid-state lithium-air batteries based on LiIHPN as the electrolyte exhibit a reversible discharge capacity of more than 2100 mAh g(-1) with a cyclic performance over 10 cycles. Our findings provide a new way to design solid-state electrolytes toward high-performance lithium-air batteries.

Small molecule activation by mixed methyl/methylidene rare earth metal complexes.

Diverse reactivity patterns of mixed tetramethyl/methylidene rare-earth complexes bearing bulky benzamidinate coligands L3Ln3(µ2-Me)3(µ3-Me)(µ3-CH2) [L = [PhC(NC6H3(i)Pr2-2,6)2](-); Ln = Y(), Lu()] with PhCN, alkynes, and CS2 have been established. Reaction of complexes with PhCN gave the µ3-CH2 addition complexes (NCN(dipp))3Lu3(µ2-Me)3(µ3-Me)[µ-η(1):η(1):η(3)-CH2C(Ph)N] [Ln = Y(), Lu()]. Treatment of complexes with phenylacetylene afforded unexpected alkenyl dianion complexes L3Ln3(µ2-Me)3(µ3-Me)(µ-η(1):η(3)-PhC[double bond, length as m-dash]CMe) [Ln = Y(), Lu()] through the insertion of rare earth methylidene into a C-H bond in a reductive fashion. However, reaction of complexes and HC[triple bond, length as m-dash]CSiMe3 gave µ3-Me protonolysis complexes L3Ln3(µ2-Me)3(µ3-C[triple bond, length as m-dash]CSiMe3)(µ3-CH2) [Ln = Y (), Lu ()] in excellent yields. Treatment of complexes with CS2 led to the formation of the methyl activation complexes L3Ln3(µ2-Me)2(µ3-CH2)(µ3-η(1):η(2):η(2)-S2C[double bond, length as m-dash]CH2) [Ln = Y(), Lu()]. All the new complexes were fully characterized.

Mono-cadmium vs Mono-mercury Doping of Au25 Nanoclusters.

Controlling the dopant type, number, and position in doped metal nanoclusters (nanoparticles) is crucial but challenging. In the work described herein, we successfully achieved the mono-cadmium doping of Au25 nanoclusters, and revealed using X-ray crystallography in combination with theoretical calculations that one of the inner-shell gold atoms of Au25 was replaced by a Cd atom. The doping mode is distinctly different from that of mono-mercury doping, where one of the outer-shell Au atoms was replaced by a Hg atom. Au24Cd is readily transformed to Au24Hg, while the reverse (transformation from Au24Hg to Au24Cd) is forbidden under the investigated conditions.

Synthesis and Properties Evolution of a Family of Tiara-like Phenylethanethiolated Palladium Nanoclusters.

Tiara-like thiolated group 10 transition metal (Ni, Pd, Pt) nanoclusters have attracted extensive interest due to their fundamental scientific significance and potential application in a number of fields. However, the properties (e.g. the absorption) evolution with the ring size's increase was not investigated so far to our best knowledge, due to the challenge of obtaining a series of nanocluster analogues. Herein, we successfully synthesized, isolated and identified a family of [Pd(SC2H4Ph)2]n nanoclusters (totally 17 novel clusters, n = 4-20). Their structures were determined to be tiara-like by single crystal X-ray crystallography together with theoretical calculation; their formation mechanism was proposed to be a substitution-polycondensation-ring-closure process based on experimental observations. All of these clusters are rather robust (anti-reductive and anti-oxidative) owing to their tiara-like structures with large HOMO-LUMO gaps. Finally, the optical and electrochemical evolution with the increase of ring size was investigated, and it is found that both optical and electrochemical gaps have a "turning point" at a size corresponding to n = 8 for [Pd(SR)2]n nanoclusters.

The marriage of endo-cavity and exo-wall complexation provides a facile strategy for supramolecular polymerization.

Butylated pillar[5]arene (1) and N,N'-bis(n-butyl)pyromellitic diimide (2) form a 2 : 1 sandwich-type complex external to the walls of the receptor ("exo-wall" complex). The marriage of exo-wall interactions and endo-cavity inclusion provides a new strategy for the construction of supramolecular polymers from unfunctionalized neutral receptors.

A rod-packing microporous hydrogen-bonded organic framework for highly selective separation of C2H2/CO2 at room temperature.

Self-assembly of a trigonal building subunit with diaminotriazines (DAT) functional groups leads to a unique rod-packing 3D microporous hydrogen-bonded organic framework (HOF-3). This material shows permanent porosity and demonstrates highly selective separation of C2H2/CO2 at ambient temperature and pressure.

Octadecanuclear macrocycles and nonanuclear bowl-shaped structures based on two analogous pyridyl-substituted imidazole-4,5-dicarboxylate ligands.

Two types of unprecedented Cp*Rh-based (Cp* = η(5)-C5Me5) complexes, two octadecanuclear macrocycles, and a nonanuclear bowl-shaped complex have been synthesized from two analogous pyridyl-functionalized imidazole-4,5-dicarboxylate ligands, 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylate ligand and 2-(pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate ligand, respectively.

A microporous six-fold interpenetrated hydrogen-bonded organic framework for highly selective separation of C2H4/C2H6.

A unique six-fold interpenetrated hydrogen-bonded organic framework (HOF) has been developed, for the first time, for highly selective separation of C2H4/C2H6 at room temperature and normal pressure.

Ordered vacancies and their chemistry in metal-organic frameworks.

Vacancies are common in solid materials, but it remains a challenge to introduce them at specific locations with controlled distributions. Here we report the creation of ordered metal vacancies and linker vacancies in a cubic metal-organic framework (MOF) based on Zn(II) and pyrazolecarboxylic acid by removing a quarter of the metal ions and half of the linkers. The MOF with ordered vacancies shows increased pore size, thus allowing large dye molecules to fit in the pores. Furthermore, by filling the vacancies with new metals and new linkers, eight new single-crystalline MOFs with multicomponents in absolute order are introduced. The capability of performing stepwise elimination and addition reactions systematically in extended solids without destroying the structural integrity has generated complex MOF structures which otherwise cannot be made.

H2-initiated reversible switching between two-dimensional metallacycles and three-dimensional cylinders.

Although reversible covalent activation of molecular hydrogen (H2) by transition-metal complexes is a common reaction, H2-mediated sophisticated reversible arrangements of organometallic frameworks have not yet been described. Herein, we report unusual organometallic transformations in solution that can be accomplished by uptake or release of H2. An efficient route for synthesizing air- and moisture-stable 16-electron M2L2-type metallacycles under very mild conditions has been developed. The new organometallic metallacycles favor the binding of small ligands such as MeCN, Cl(-), CO, and pyridine. The reaction of a coordinatively unsaturated 16-electron M2L2-type macrocyclic complex featuring thione ligands with 1 atm of H2 leads to the isolation of a 18-electron M2L3-type cylinder, along with hydride species. Remarkably, the obtained mixture underwent loss of H2 in a facile manner upon heating to re-form the starting M2L2-type complex. A possible mechanism is proposed for the reversible transformations.

Homometallic rare-Earth metal phosphinidene clusters: synthesis and reactivity.

Two new trinuclear µ3 -bridged rare-earth metal phosphinidene complexes, [{L(Ln)(µ-Me)}3 (µ3 -Me)(µ3 -PPh)] (L=[PhC(NC6 H4 iPr2 -2,6)2 ](-) , Ln=Y (2 a), Lu (2 b)), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120 °C leads to an unprecedented ortho CH bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha-Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS2 leads to the formation of novel trinuclear rare-earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation.

Reactivity of Tp(Me2) -supported yttrium alkyl complexes toward aromatic N-heterocycles: ring-opening or C-C bond formation directed by C-H activation.

Unusual chemical transformations such as three-component combination and ring-opening of N-heterocycles or formation of a carbon-carbon double bond through multiple C-H activation were observed in the reactions of Tp(Me2) -supported yttrium alkyl complexes with aromatic N-heterocycles. The scorpionate-anchored yttrium dialkyl complex [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with 1-methylimidazole in 1:2 molar ratio to give a rare hexanuclear 24-membered rare-earth metallomacrocyclic compound [Tp(Me2) Y(µ-N,C-Im)(η(2) -N,C-Im)]6 (1; Im=1-methylimidazolyl) through two kinds of C-H activations at the C2- and C5-positions of the imidazole ring. However, [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with two equivalents of 1-methylbenzimidazole to afford a C-C coupling/ring-opening/C-C coupling product [Tp(Me2) Y{η(3) -(N,N,N)-N(CH3 )C6 H4 NHCHC(Ph)CN(CH3 )C6 H4 NH}] (2). Further investigations indicated that [Tp(Me2) Y(CH2 Ph)2 (THF)] reacted with benzothiazole in 1:1 or 1:2 molar ratio to produce a C-C coupling/ring-opening product {(Tp(Me2) )Y[µ-η(2) :η(1) -SC6 H4 N(CHCHPh)](THF)}2 (3). Moreover, the mixed Tp(Me2) /Cp yttrium monoalkyl complex [(Tp(Me2) )CpYCH2 Ph(THF)] reacted with two equivalents of 1-methylimidazole in THF at room temperature to afford a trinuclear yttrium complex [Tp(Me2) CpY(µ-N,C-Im)]3 (5), whereas when the above reaction was carried out at 55 °C for two days, two structurally characterized metal complexes [Tp(Me2) Y(Im-Tp(Me2) )] (7; Im-Tp(Me2) =1-methyl-imidazolyl-Tp(Me2) ) and [Cp3 Y(HIm)] (8; HIm=1-methylimidazole) were obtained in 26 and 17 % isolated yields, respectively, accompanied by some unidentified materials. The formation of 7 reveals an uncommon example of construction of a CC bond through multiple C-H activations.

A porous metal-organic framework constructed from carboxylate-pyrazolate shared heptanuclear zinc clusters: synthesis, gas adsorption, and guest-dependent luminescent properties.

A three-dimensional porous structure of [Zn7O2(bpdc)4(dmpp)2]·6DEF·10H2O (MAC-7, H2bpdc = 4,4'-biphenyldicarboxylic acid, Hdmpp = 3,5-dimethyl-4-(4'-pyridyl)pyrazole), built of 12-bridged carboxylate-pyrazolate shared Zn7O2 clusters, has been synthesized. Because of the presence of 12-bridged carboxylate-pyrazolate shared building block, MAC-7 is a double-linked pcu-type framework and shows reversible phase transformation. Photoluminescent property studies indicate that MAC-7 could sense nitrobenzene over toluene, p-xylene, and mesitylene by luminescent quenching.