Dalton Transactions Blog

Adam Veige and colleagues from the University of Florida, USA, report the successful isolation of the neutral ONO^3- trianionic pincer-type tungsten alkylidyne complex [CF₃–ONO]WΞC(^tBu)(OEt₂).

Cyclooctyne, which is normally polymerised due to its internal ring strain, reacts rapidly with the pincer-type tungsten alkylidyne complex to give the first example of a bicyclic metallacyclobutadiene.  The pincer-type tungsten alkylidyne complex was also treated with alkyne substrates 1-phenylpropyne and 4,4-dimethyl-2-pentyne to give two more tungstenacyclobutadienes. The three tungstenacyclobutadienes made in this study all exhibit incredible stability.

Download the paper today to read how the team have explored the factors contributing to this stability.

Unusually stable tungstenacyclobutadienes featuring an ONO trianionic pincer-type ligand
Matthew E. O’Reilly, Ion Ghiviriga, Khalil A. Abboud and Adam S. Veige
Dalton Trans., 2013
DOI: 10.1039/C2DT32653A

You might also be interested in this Dalton Transactions article by the same authors:

The influence of reversible trianionic pincer OCO³⁻μ-oxo Cr^IV dimer formation ([Cr^IV]₂(μ-O)) and donor ligands in oxygen-atom-transfer (OAT)
Matthew E. O’Reilly, Trevor J. Del Castillo, Khalil A. Abboud and Adam S. Veige
Dalton Trans., 2012,41, 2237-2246
DOI: 10.1039/C1DT11104C, Paper

Scientists in Italy and Brazil report a new synthesis for making heteronuclear propeller-like single molecule magnets (SMMs) that could be used to design structures with a variety of d- and f-block metals and R groups, yielding 100% pure complexes without metal scrambling. 

There is considerable interest in manipulating SMMs to have higher ground spin states, enhanced magnetic properties and increased robustness for possible future applications in quantum computing.  In this study, Roberta Sessoli and colleagues use a central chromium(III) ion in their synthesis of Fe₃Cr propeller-like aggregates to show that molecular ground spin state can be altered by selectively changing the spin state of the metal ion.

The chemically inert chromium(III) produces a kinetically stable central “core” which then combines with the dimeric iron(III) starting material to give propeller-like complexes

The synthetic method could potentially be tailored to produce propeller-like SMMs with particular properties.

Read more about the synthesis for free at…

A new approach to the synthesis of heteronuclear propeller-like single molecule magnets
Pasquale Totaro,  Kátia Cristina M. Westrup,  Marie-Emmanuelle Boulon,  Giovana G. Nunes,  Davi F. Back,  Andersson Barison,  Samuele Ciattini,  Matteo Mannini,  Lorenzo Sorace,  Jaísa F. Soares,  Andrea Cornia and Roberta Sessoli
Dalton Trans., 2013
DOI: 10.1039/C2DT32618C

Here are some other Dalton Transactions articles by the same authors:

Lanthanides in molecular magnetism: so fascinating, so challenging
Javier Luzon and Roberta Sessoli
Dalton Trans., 2012, 41, 13556-13567
DOI: 10.1039/C2DT31388J, Perspective
From themed issue Frontier and Perspectives in Molecule-Based Quantum Magnet

Magnetic and optical bistability in tetrairon(III) single molecule magnets functionalized with azobenzene groups
Thazhe Kootteri Prasad, Giordano Poneti, Lorenzo Sorace, Maria Jesus Rodriguez-Douton, Anne-Laure Barra, Petr Neugebauer, Luca Costantino, Roberta Sessoli and Andrea Cornia
Dalton Trans., 2012, 41, 8368-8378
DOI: 10.1039/C2DT30172E, Paper

Dimers and chains of {3d–4f} single molecule magnets constructed from heterobimetallic tectons
Traian D. Pasatoiu, Mael Etienne, Augustin M. Madalan, Marius Andruh and Roberta Sessoli
Dalton Trans., 2010, 39, 4802-4808
DOI: 10.1039/B925425K, Paper
From themed issue Molecular magnets

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Upon DNA binding, a 15-fold turn-on in emission intensity occurs.

Stephen Lippard and colleagues at Massachusetts Institute of Technology have synthesised and characterised a platinum(II) complex bearing the tetradentate, β-diketiminate ligand ([Pt(BDIQQ)]Cl).  Cytotoxic studies showed [Pt(BDIQQ)]Cl to have similar potency to cisplatin on cervical cancer (HeLa) cells, whereas on human lung carcinoma (A549) cells [Pt(BDIQQ)]Cl was four times more potent than cisplatin.  The complex elicits a strong photoluminescent turn-on response upon DNA binding and it is hoped this will be useful for further cellular imaging studies.

Read the article now to find out more…

Photoluminescent DNA binding and cytotoxic activity of a platinum(II) complex bearing a tetradentate β-diketiminate ligand
Jennifer M. Hope, Justin J. Wilson and Stephen J. Lippard
Dalton Trans., 2013
DOI: 10.1039/C2DT32462H, Communication

Other Dalton Transactions articles by this author include:

A C2-symmetric, basic Fe(III) carboxylate complex derived from a novel triptycene-based chelating carboxylate ligand
Yang Li, Justin J. Wilson, Loi H. Do, Ulf-Peter Apfel and Stephen J. Lippard
Dalton Trans., 2012,41, 9272-9275
DOI: 10.1039/C2DT31260C, Communication

Non-traditional platinum compounds for improved accumulation, oral bioavailability, and tumor targeting
Katherine S. Lovejoy and Stephen J. Lippard
Dalton Trans., 2009, 10651-10659
DOI: 10.1039/B913896J, Perspective
From themed issue Metal anticancer compounds

Konstantin Shuvaev, Annie K. Powell and colleagues have designed a ligand containing the nitronyl nitroxide radical.  The ligand can self-assemble with copper(II) ions to give a [2 x 2] grid complex.

The nitronyl nitroxide radical coordinated via the oxo-atom of the N+-O- fragment in a chelating fashion and lies in the equatorial plane of the metal ion.

The high reactivity of organic radicals makes them difficult to use but the nitronyl nitroxide radical is one of the most stable and so can be used in the design of paramagnetic polytopic ligands as building blocks for supramolecular grids.  Most previous supramolecular grids have been made using diamagnetic ligands but the team found that being able to use a paramagnetic ligand resulted in a grid with interesting spin coupling and magnetic properties.

Read more for free at…

A self-assembled Cu(II)4 [2 × 2] grid with organic radicals
Konstantin V. Shuvaev, Stephen Sproules, J. Mikko. Rautiainen, Eric J. L. McInnes, David Collison, Christopher E. Anson and Annie K. Powell
Dalton Trans., 2012
DOI: 10.1039/C2DT31946B, Paper

Korenev and colleagues present a new hybrid polyoxometalate in this HOT Dalton Transactions Communication. 

The search is on to enhance the structural diversity of POMs and one approach to this is to “hybridise” — a POM structure can be designed to also include a stable polynuclear unit. Several POM structures containing oxothiocations have been synthesised with this in mind, yielding structures with both hard and soft coordination centres.

Korenev and team have used this approach to synthesis a unique architecture that consists of two tungstoborate subunits which are linked with a hexamolybdate “handle” (shown in pink).

To find out more, you can download the Communication now – which is free to access for 4 weeks!

Trapping {BW₁₂}₂ tungstoborate: synthesis and crystal structure of hybrid [{(H₂BW₁₂O₄₂)₂O}{Mo₆O₆S₆(OH)₄(H₂O)₂}]₁₄− anion
V. S. Korenev, P. A. Abramov, C. Vicent, D. A. Mainichev, S. Floquet, E. Cadot, M. N. Sokolov and V. P. Fedin
Dalton Trans., 2012
DOI: 10.1039/C2DT31512B, Communication

It’s estimated that there’s more than 4.5 billion tons of uranium in the ocean

US scientists have used a ligand that can form a complex with a uranyl ion to enable uranium to be extracted from seawater. The concentration of uranium in seawater is low at 3.3 parts per billion, but in the vast oceans, it’s estimated that there’s more than 4.5 billion tons of uranium; considerably more than the amount of uranium in terrestrial ores, say the researchers.

Extracting uranium from the sea is a challenge because it exists as a stable carbonate complex. Linfeng Rao from the Lawrence Berkeley National Laboratory, and colleagues, say that a cyclic imide dioxime ligand – glutarimidedioxime – can compete with carbonate to bind strongly to the uranyl ion to form the complex.

Rao says that there are two unique features in the structure of the uranium–glutarimidedioxime complex. ‘The protons of both oxime groups (–CH=N–OH) are rearranged from the oxygen atom to the nitrogen atom,’ he explains. ‘The middle imide group (–CH–NH–CH–) is deprotonated, resulting in a -1 charged ligand that coordinates to the uranyl cation in a tridentate mode (via the two oxime oxygen atoms and the imide nitrogen atom).’ With such a configuration, he adds, the electron density on the ligand could be delocalised, forming a conjugated system that coordinates strongly to the uranyl cation.

‘It will be interesting to learn how the ligand performs in competition with a peroxide anion, which forms an even stronger complex than carbonate with the uranyl ion in the natural marine photic zone,’ says Mark Antonio, a separation science expert from Argonne National Laboratory, US. He adds that the results from the investigation provide insights that may lead to a viable sequestration of uranium from amongst a myriad other cations.

‘Uranium availability becomes even more important as developing countries such as China and India are ramping up their nuclear power capacities,’ says Wenbin Lin, whose group from the University of North Carolina at Chapel Hill, US, focuses on addressing  fundamental chemical problems relevant to societal issues. ‘If an economically viable technology can be developed to extract uranium from seawater, nuclear power becomes a virtually sustainable clean energy source.’

Sequestering uranium from seawater: binding strength and modes of uranyl complexes with glutarimidedioxime
Guoxin Tian,  Simon Teat,  Zhiyong Zhang and Linfeng Rao
Dalton Trans., 2012
DOI: 10.1039/C2DT30978E