Dalton Transactions Blog

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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A team of researchers from France, Spain and Russia have put forward a case to explain a counter-intuitive conformation of manganese alkylalkoxycarbene complexes.

Using molecular orbitals, it is predicted that such complexes adopt a vertical coordination mode. This is largely the case – although one exception reported by Landman et al. earlier this year (see here) prompted the team to investigate what really is going on…

Coordination modes of carbene ligands in piano-stool complexes

Using a combination of DFT calculations and XRD analysis, Lugan et al. confirm that non-covalent interligand interactions between the alkyl substituents on the carbene and the carbon monoxide ligand (C-H^…C≡O) are responsible for these complexes adopting the unexpected horizontal coordination mode. Although such an interaction is weak, it goes to show that its enough to influence geometry.

Download the article now…

On the incidence of non-covalent intramolecular interligand interactions on the conformation of carbene complexes: a case study
Noël Lugan, Israel Fernández, Rémy Brousses, Dmitry A. Valyaev, Guy Lavigne and Nikolai A. Ustynyuk
Dalton Trans., 2013, Advance Article

Plutonium colloids

Even 70 years after its discovery, the behaviour of plutonium still remains something of an enigma.  Now Swedish researchers have discovered that plutonium colloids shrink with age becoming very small (3–4 atoms) with a shortening of the average Pu–O bond and Pu⋯Pu distances, consistent with partial oxidation having occurred.  Two types of colloidal materials were studied: high-fired crystalline PuO2, and freshly prepared Pu(IV) colloids. The structures of both types were determined by EXAFS at the beginning of the experiment and after controlled aging of up to five years.  The results show that even freshly prepared Pu(IV) colloids are polynuclear nano clusters with PuO2 structure, bringing new insight into the evolution of plutonium with time.

The structure of plutonium(IV) oxide as hydrolysed clusters in aqueous suspensions
Christian Ekberg, Kristian Larsson, Gunnar Skarnemark, Arvid Ödegaard-Jensen and Ingmar Persson
Dalton Trans., 2013, Advance Article
DOI: 10.1039/C2DT32185H

Other Dalton papers by the same author are:

Crystal structure of [Eu(CyMe₄-BTBP)₂κ²O,O‘-(NO₃)](NO₃)₂·n-C₈H₁₇OH and its structure in 1-octanol solution
Daniel Lundberg, Ingmar Persson and Christian Ekberg
Dalton Trans., 2013, Advance Article
DOI: 10.1039/C2DT32317F, Communication

Radiolysis of solvents containing C5-BTBP: identification of degradation products and their dependence on absorbed dose and dose rate
Anna Fermvik, Laurence Berthon, Christian Ekberg, Sofie Englund, Teodora Retegan and Nicole Zorz
Dalton Trans., 2009, 6421-6430
DOI: 10.1039/B907084B, Paper

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

With TONs up to 9000 H₂/Co this Hot Communication by Peter Hamm and Roger Alberto et al. is worth a read.

The team have developed a stable, water reducing catalyst which operates under acidic conditions and indicates poly-pyridyl ligand frameworks are superior to some of the other commonly used chelators. They also show the cobalt complex retains catalytic activity when resin bound, meaning it is active as both a homogeneous and heterogeneous catalyst. For full details download the article below.

A highly stable polypyridyl-based cobalt catalyst for homo- and heterogeneous photocatalytic water reduction
Miguel Guttentag, Alexander Rodenberg, Cyril Bachmann, Anna Senn, Peter Hamm and Roger Alberto
Dalton Trans., 2012, Advance Article

The catalytic potential of metal nanoparticles is widely understood and some are already used for heterogeneous catalysis.  In a dedication to Professor Cole-Hamilton, Karine Philippot and Bruno Chaudret et al. report the synthesis and characterisation of uniquely stabilised RuPt nanoparticles.

A diphenylphospine was used to stabilise bimetallic RuPt nanoparticles, both decorating them and affecting their chemical composition.  Neither an ordered alloy nor a core-shell structure was produced; instead, as proven by scattering and spectroscopic techniques, very disordered nanoparticles with Ru cores and alloy shells were observed. The mechanism that produces such an “onion” structure is thought to involve the reaction of the diphosphine ligands with Ru at the beginning of the reaction.

The use of reactive ligands in the synthesis of bimetallic nanoparticles can modify their structure, suggesting the possibility of finely tailoring the structure and surface of such nanoparticles in the future.  These modifications have already shown promise, with CO poisoning of RuPt nanoparticles having much less of an effect on hydrogenation reactions than with analagous pure Ru examples.

To find out more about these new bimetallic nanoparticles, download this HOT article now.

On the influence of diphosphine ligands on the chemical order in small RuPt nanoparticles: combined structural and surface reactivity studies
Patricia Lara, Tuğçe Ayvalı, Marie-José Casanove, Pierre Lecante, Alvaro Mayoral, Pier-Francesco Fazzini, Karine Philippot and Bruno Chaudret

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

Scientists in Mexico and Spain have synthesised a ruthenium complex using a N-heterocyclic CNC pincer ligand.

Lutidine-derived pincer complexes are well established amongst organometallic chemists. More traditionally, the pincer ligand motif, PNX has been utilised (where P is a phosphine and X is either a phosphine or N donor ligand) but substitution of phosphines with stronger electron-donating N-heterocyclic carbenes has meant that more active catalytic species have been made for promoting hydrogenation of non-active esters. Mostly speaking, these ligands follow a CNN coordination pattern. According to the researchers, the only CNC pincer complex reported coordinates to the ruthenium centre in a mer geometry.

In their latest Dalton Transactions Communication, the team report on the synthesis of a CNC ligand which coordinates to ruthenium in an usual fac mode. They proved that the resultant complex can be used to catalyse the hydrogenation of imines by firstly deprotonating one of the ligand methylene bridges.

To read more about this development, read the full article now…

Hydrogenation of imines catalysed by ruthenium(II) complexes based on lutidine-derived CNC pincer ligands
Martín Hernández-Juárez, Mónica Vaquero, Eleuterio Álvarez, Verónica Salazar and Andrés Suárez
Dalton Trans., 2012, Advance Article

As Jason Love described in his 2009 ChemComm Feature Article, pyrrole-based macrocycles are ideal ligands for creating pre-organised metal binding sites to enable the multielectron redox chemistry so required for transforming small molecules such as O₂, carbon dioxide and water.

Here in their latest Dalton Transactions article, Love and colleagues take this a step further.

The team note how their previous attempts to make mononuclear transition metal complexes with the donor ligands were unsuccessful. Despite significant efforts, they could only make bimetallic complexes – well, until now that is…

The newest set of ligands now incorporate N₄^¬ with either O₅ or ONO donors which are separated through aryl spacers. Upon binding of a singular metal atom, the complexes fold to form a Pacman-like cleft structure. Love and colleagues expect the structure to play host to guest molecules which can benefit from metal coordination as well as hydrogen bonding interactions to the oxygen and nitrogen atom acceptors.

To read more, download the article now… 

Synthesis and structures of transition metal pacman complexes of heteroditopic Schiff-base pyrrole macrocycles
James W. Leeland, Colin Finn, Bérengère Escuyer, Hiroyuki Kawaguchi, Gary S. Nichol, Alexandra M. Z. Slawin and Jason B. Love