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The high fluorophilicity of borane-containing ligands offers promise for accessing new metallodrug candidates capable of bifunctional [18F]-positron emission tomography (PET) imaging, but this requires water soluble and hydrolytically stable ligands that can be fluorinated under mild conditions. Toward this goal, here we report the synthesis and characterization of water-soluble Pt(II) complexes containing a triaminoborane-bridged diphosphoramidite ligand called MeOTBDPhos that can be fluorinated using simple fluoride salts. NMR and XRD studies show that (MeOTBDPhos)PtCl2 (1) dissolves in water with cooperative H–OH addition across the bridgehead N–B bond to form 1-H2O. The B–OH bond in 1-H2O undergoes rapid displacement with fluoride (<10 min) when treated with CsF in MeCN to form 1-HF. 1-HF can also be prepared in <10 min by addition of KF to 1 in the presence Kryptofix® 222 and (HNEt3)Cl in MeCN. In addition to using fluoride salts, we show how mononuclear 1 can be fluorinated with HBF4·Et2O to form dinuclear [(MeOTBDPhos-HF)Pt(μ-Cl)]2(BF4)2 (4-HF). Comparative studies show that the B–F bond in 1-HF undergoes hydrolysis as soon as it is dissolved in water or saline, but the B–F bond persists for hours when the pH of the solution is lowered to pH ≤ 2. In contrast to 1-HF, the B–F bond in dinuclear 4-HF persists for days when dissolved in water, which may be attributed to slow, sacrificial release of fluoride from the BF4− anion. The results show how cooperative N–B reactivity on the ligand can be leveraged to rapidly fluorinate water-soluble MeOTBDPhos complexes under mild conditions and afford suggestions for how to enhance hydrolytic B–F stability, as required for use in biomedical applications. [ABSTRACT FROM AUTHOR]

A method to rapidly diversify the molecules formed in organic crystals is introduced, with aryl nitriles playing a novel dual role as both hydrogen‐bond acceptors and modifiable organic groups. The discovery of coexisting supramolecular synthons in the same crystal is also described. The general concept is demonstrated by using a bis(aryl nitrile) alkene that undergoes a hydrogen‐bond‐directed intermolecular [2+2] photodimerization to form a tetra(aryl nitrile)cyclobutane. The product is readily converted by click reactivity to a tetra(aryl tetrazole) and by hydrolysis to a tetra(aryl carboxylic acid). The integration of aryl nitriles into solid‐state reactions opens broad avenues to post‐modify products formed in crystalline solids for rapid diversification. [ABSTRACT FROM AUTHOR]

Cocrystallizations of diboronic acids [1,3‐benzenediboronic acid (1,3‐bdba), 1,4‐benzenediboronic acid (1,4‐bdba) and 4,4'‐biphenyldiboronic acid (4,4'‐bphdba)] and bipyridines [1,2‐bis(4‐pyridyl)ethylene (bpe) and 1,2‐bis(4‐pyridyl)ethane (bpeta)] generated the hydrogen‐bonded 1 : 2 cocrystals [(1,4‐bdba)(bpe)2] (1), [(1,4‐bdba)(bpeta)2] (2), [(1,3‐bdba)(bpe)2(H2O)2] (3) and [(1,3‐bdba)(bpeta)2(H2O)] (4), wherein 1,3‐bdba involved hydrated assemblies. The linear extended 4,4'‐bphdba exhibited the formation of 1 : 1 cocrystals [(4,4'‐bphdba)(bpe)] (5) and [(4,4'‐bphdba‐me)(bpeta)] (6). For 6, a hemiester was generated by an in‐situ linker transformation. Single‐crystal X‐ray diffraction revealed all structures to be sustained by B(O)−H⋅⋅⋅N, B(O)−H⋅⋅⋅O, Ow−H⋅⋅⋅O, Ow−H⋅⋅⋅N, C−H⋅⋅⋅O, C−H⋅⋅⋅N, π⋅⋅⋅π, and C−H⋅⋅⋅π interactions. The cocrystals comprise 1D, 2D, and 3D hydrogen‐bonded frameworks with components that display reactivities upon cocrystal formation and within the solids. In 1 and 3, the C=C bonds of the bpe molecules undergo a [2+2] photodimerization. UV radiation of each compound resulted in quantitative conversion of bpe into cyclobutane tpcb. The reactivity involving 1 occurred via 1D‐to‐2D single‐crystal‐to‐single‐crystal (SCSC) transformation. Our work supports the feasibility of the diboronic acids as formidable structural and reactivity building blocks for cocrystal construction. [ABSTRACT FROM AUTHOR]

Research has been conducted on the octahedral hexanuclear cluster halides of the transition metals. The low temperature solid-state approaches to these compounds carried out via the reduction of TaCl (sub)5 with gallium and gallium dichloride have been investigated and the results are reported.

Research has been conducted on the sterically bulky, dimeric diethylamido-bridged gallium hydride. The synthesis of this compound and related chloride derivatives and the studies of the preliminary chemical vapor deposition have been carried out and are discussed.

Tube furnace reduction of WCl6 with mercury, bismuth or antimony represents three new easy and convenient approaches for the efficient preparation of crystalline ((WCl4)x). The easiest and highest-yield methods for the preparation of (WCl4)x were the solid-state reduction of WCl6 with antimony and reduction of WCl6 with tin in dichloroethane. The molecular structure of (WCl4)x is comprised of chains of a linear polymer of opposite-edge-sharing bioctahedra with alternating short and long W***W distances.

(PPN)(Tl(C2B9H11)) reacts with (C2B9H11)TaCl3 in a medium of CH2Cl2 to produce (PPN)((C2B9H11)2TaCl2) having a bent-metallocene structure. This complex helps prepare two other complexes having a bent-metallocene structure analogous to those of Cp2MX2 complexes. X-ray and multinuclear NMR studies help characterize these anionic tantalum(V)bis(dicarbollide) complexes.

Trans-1,4-dialdehyde 4a was obtained as the major product from the stereoselective low-temperature diisobutylaluminum hydride (DIBALH) reduction of the title tetraester 3 and novel 1,1,4,4-tetrasubstituted cyclohexanes consisting of trans-1,4-difluoromethyl and fluoromethyl groups from the fluorination of 4a, b and subsequent additional elaboration. Reduction of merely a single ester group ensues from the treatment of dimethyl 1,1-cycloalkyl diesters with excess DIBALH.

The dimerization reaction of fluorinated alpha-halovinyl zinc and copper reagents and their thermal stability was explored. The structures of each of the isomeric members of butatrienes were characterized by X-ray crystallography. Dimerization of these vinyl carbenoids to butatrienes occurs when R is an aromatic C6H5 or C6F5 and R' is a perfluoroalkyl group CF3, C2F5, C3F7.

The d0 carbonyl complex Cp2Zr(CH)(Me)(6-ethlpyrid-2-yl))+ (compound 3) results from the carbonylation of the four-membered cationic azazirconacyle. A terminal CO ligand is evident for compound 3. A chelated structure in Zr(CH(Me)(6-ethylpyrid-2-yl) ligand is evident. In the case of azazirconacyle, back-bonding from only a single bonding orbital is possible.

We describe hydrogen bonds (i.e., N+–H⋯N) in combination with cation⋯π interactions to enable a cascade-like [2 + 2] photodimerization of 4-stilbazole in a salt cocrystal. A four-component crystal assembly is composed of photoactive pyridinium ion pair 4-stilbzH+ (4-stilbz = trans-1-(4-pyridyl)-2-(phenyl)ethylene) and photostable molecule pair 4-stilbz. UV irradiation gives rctt-1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane (4-pyr-ph-cb) in quantitative yield. An intermediate structure 2(4-stilbz)·(4-pyr-ph-cb)2H+ is isolated that undergoes a partial single-crystal-to-single-crystal transformation. The single-crystal X-ray data provides a snapshot of movements in the salt cocrystal in the course of the photodimerization. [ABSTRACT FROM AUTHOR]

Soft porous nanocrystals with a pronounced shape-memory effect exhibit two- to three-fold increase in elastic modulus compared to the microcrystalline counterpart as determined by atomic force microscopy nanoindentation. The increase in rigidity is consistent with the known shape-memory effect displayed by the framework solid at the nanoscale. Crystal downsizing can offer new avenues for tailoring the mechanical properties of metal–organic frameworks. [ABSTRACT FROM AUTHOR]

A structural study of two-dimensional inverted metal–organic frameworks demonstrates that the interior cavities of the framework structures can be systematically modified by changing the organic anion of a Cu(II)-paddlewheel unit. Changing the anion allows modifications to the shapes and sizes of the cavities in a series of isoreticular frameworks. The construction of the frameworks is based on the application of a tetrafunctional organic cyclobutane ligand synthesized in the organic solid state. [ABSTRACT FROM AUTHOR]

We report supramolecular repurposing of emtricitabine (FTC, trade name: Emtriva®), a blockbuster FDA-approved anti-HIV agent. FTC is revealed to act as a hydrogen-bonded cleft for bipyridine recognition. The supramolecular repurposing is realized by the generation of four cocrystals through liquid-assisted grinding. The clefts comprise discrete three-component assemblies sustained by a combination of hydrogen bonds and π⋯π interactions. [ABSTRACT FROM AUTHOR]

A single electron transfer (SET) mechanism, that involved the reaction between arenethiolate nucleophiles and perfluorodecalin was proposed for the defluorination reaction. Substrates having a tertiary or quarternary carbon or element of unsaturation exhibited a greater proclivity toward defluorination through the SET mechanism.

A series of complexes [Tp.sup.R,RE]CoL, where [Tp.sup.R,RE] = hydrotris(3-R,5-RE-pyrazol-1-yl)borate (escorpionateE) anion (R = tert-butyl, RE = H, Me, 2E-thienyl (Tn), L = [Cl.sup.-], [NCS.sup.-], [NCO.sup.-], [N.sub.3.sup.-]), are studied by using electron absorption spectroscopy in the visible and near-infrared (near-IR) region and by high-frequency and ufield electron paramagnetic resonance (HFEPR). The electronic structure and bonding in pseudotetrahedral cobalt(II) complexes have increased the understanding of similar sites in metalloproteins, specifically cobalt-substituted zinc enzymes.

Photoirradiation of a binary cocrystal composed of two different cyclic dienes generates a highly-symmetric cubane-like tetraacid cage regioselectively and in quantitative yield. The cage forms by a double [2+2] photodimerization of one of the diene cocrystal components. The second diene while photostable in the cocrystal reacts in a double [2+2] photodimerization as a pure form quantitatively to form a tetramethyl cubane-like cage. The stereochemistry of the cage is structurally authenticated. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of 2,5,8-triazido-s-heptazine, which is a rare example of a fully conjugated, polycyclic all carbon and nitrogen molecular compound is reported. The large numbers of nitrogen lone pairs present in 2,5,8-triazido-s-heptazine make it attractive as a component in a supramolecular metal coordination framework.

B←N coordination supports a [2+2] photodimerization in the solid state. The bond is defined by an orthogonal interaction between stilbazole and a phenylboronic ester to enable a stereocontrolled and rapid photoreaction. The cyclobutane photoproduct affords a novel diboron bis‐tweezer adduct that is used to separate a mixture of benzene and thiophene upon crystallization. Something in the way it binds: B←N interaction of boronic esters and pyridines was used to facilitate a regioselective [2+2] photodimerization in the solid state for the first time to generate a diboron tweezer host. Selective uptake of thiophene from a mixture of benzene/thiophene was facilitated by generated host. [ABSTRACT FROM AUTHOR]

Propynylidene 1 (HCCCH) is the simplest alkynylcarbene that, along with abundant interstellar cyclopropenylidene 2 and propadienylidene 3 has attracted substantial interest. The propynylidene can be generated as an organodimetallic ligand in solution by double C-H activation of allene and it can adopt a curved structure.

Strong hydrogen-bonding interactions are predictably leveraged for local molecular docking; however, weak intermolecular interactions are being increasingly recognized as pivotal governors of extended, supramolecular assembly. In this report, a series of nitrobenzoic acids (NBA) –m-nitrobenzoic acid (3-NBA), p-nitrobenzoic acid (4-NBA), 4-methyl-3-NBA (Me-NBA), 4-chloro-3-NBA (Cl-NBA) and 4-bromo-3-NBA (Br-NBA) – are utilized to systematically adjust weak C–H…O (nitro) and C–H…O (carboxyl) bonding interactions and discriminate their influence on the crystal structure, aggregate elasticity and compaction performance. The expected carboxylic acid dimer persists across the entire NBA series; however, alternative organization of C–H…O interactions yields distinct 1-d tapes. The acoustic frequency distributions obtained from powder Brillouin light scattering (BLS) spectra provide supportive interpretation of the strength and anisotropy of the reorganized intermolecular interactions. Aggregate Young's moduli displayed a narrow range from 13.5 GPa for Br-NBA to 9.8 GPa for 3-NBA. However, the maximum longitudinal moduli (Mmax), calculated from the high-frequency cutoff, revealed significant differences in the strength of intermolecular interactions along the 1-d tapes. For 3-NBA, the extended organization of several co-linear C–H…O (nitro) interactions yielded an Mmax of 42.0 GPa, while the remaining NBA materials displayed an Mmax near 25 GPa. From powder compaction studies, the tabletability rank order was observed as: 3-NBA ＞ 4-NBA ＞ Me-NBA ≈ Br-NBA ≈ Cl-NBA; however, none of the materials achieved a tensile strength greater than 1 MPa. Overall, even minor redistribution of weak intermolecular interactions significantly modifies supramolecular assembly in NBA and detailing the specific contribution of these weak forces is required for substantive structure–performance correlation. [ABSTRACT FROM AUTHOR]

Novel routes to W6Cl12(super 8) and crystalline, reactive (WCl4)(subscript x) from reduction of WCl6 with Hg, Sb or Bi with respect to trivalent tungsten chlorides were described. Tungsten chloride is considered to have an octahedral hexatungsten structure based on powder X-ray diffraction. Two new isostructural monocapped perchlorotritungstates, the first discrete group 6 trinuclear M3(mu3-L)(mu-L)3L9 clusters with similar ligands, as well as evidence for a new chloride, W3Cl10 were presented.

The alkane elimination reaction between Cp*MMe3 (Cp* = C5-Me5; M = Zr, Hf) and C2B9H13 forms a new metallocarborane complex, (C5Me5)(sub 2)(C2B9H11)(sub 2)Hf2Me2, that adopts an unusual unsymmetrical dinuclear framework bearing bridging dicarbollide ligands. The compound has Cp*(eta to the fifth power-C2B9H11)Hf+ and Cp*HfMe(super +)(sub 2) fragments bridged by a C2B9H(super 2-)(sub 11) group. The B-H bonds in these metallocarboranes are basic and the charge is distributed over the open face and the outside of the C2B9H(super 2-)(sub 11) cage.

Co-crystallization of a symmetrical azo bipyridine with isosteric resorcinols affords isostructural co-crystals that exhibit linear thermal expansion along each axis. The thermal expansions involve interplay between intra-layer halogen and hydrogen bonds. [ABSTRACT FROM AUTHOR]

Ten N-halophenylpyridinium salts (halogen = Br or I) with chloride (and in one case iodide) counterions have been prepared and structurally characterized in order to examine the degree of solid state halogen bonding exhibited in these systems. N-Halophenylpyridinium salts are easily synthesized from existing pyridines, and the cationic pyridinium group is expected to increase the halogen bond donor ability of attached halophenyl moieties. Halide anions functioning as halogen bond acceptors facilitate formation of charge-assisted halogen bonds. All five substrates featuring iodophenyl or diiodophenyl substituents displayed the expected halogen bonding interactions. In several cases halide ion acceptors were also engaged in complementary hydrogen bonding interactions with C-H groups of pyridinium rings and O-H groups of water solvates. Halogen bond donors containing a diiodophenyl group formed either an extended network or discrete supramolecular macrocyclic constructs through ArI···Cl-···IAr bridging interactions. Significantly fewer and weaker halogen bonding interactions were observed in crystals of N-bromophenylpyridinium salts. The attenuation of halogen bonding in these substrates is attributed to the inability of the activated bromoarene halogen bond donors to compete with hydrogen bond donors (C-H/O-H residues) for the halide anion. [ABSTRACT FROM AUTHOR]

Cover Feature: Programming Rapid Functional Group Diversification into a Solid-State Reaction: Aryl Nitriles for Self-Assembly, Click Reactivity, and Discovery of Coexisting Supramolecular Synthons (Chem. Eur. J. 37/2022) Dimerization, molecular recognition, post-modification, self-assembly, solid-state reactions Keywords: dimerization; molecular recognition; post-modification; self-assembly; solid-state reactions EN dimerization molecular recognition post-modification self-assembly solid-state reactions 1 1 1 07/05/22 20220701 NES 220701 B A last piece of the puzzle b ?. [Extracted from the article]