The carbon‒metal bond and C‒H metalation: In celebration of the career of William C. Kaska

Posted on behalf of Simon M. Humphrey (Guest Editor; The University of Texas at Austin)

This themed collection on the carbon‒metal bond and C‒H metalation is devoted to the career of Professor William (Bill) Kaska, who will celebrate his 80th birthday on May the 13th, 2015. Bill was a faculty member at The University of California at Santa Barbara for the entirety of his 41-year independent career (1964‒2004). During this time, he supervised many graduate students and post-doctoral scholars, a large number of whom are active in teaching, research, and in industry positions today.

Professor William (Bill) Charles Kaska

Professor William (Bill) Charles Kaska

Throughout his career, Bill has been a true pioneer and adventurer in organometallic chemistry, bearing the innate synthetic flair and expertise to make unusual molecules where others had tried and failed. He has made several important (and perhaps under-recognized) impacts in the field of metal-mediated C‒H activation, as well as in several other areas of organometallic chemistry (see below). Perhaps most notably, Bill was one of the first researchers to realize the power of C‒H bond metalation using transition metals and his early work demonstrated some of the first reported instances of such chemistry.

During his career, Bill collaborated with many groups around the World, and was a visiting scientist at Monsanto in Zurich, at the Universities of Cambridge, Erlangen, Tübingen and Utrecht, and at the Max-Planck Institute in Mülheim. We celebrate the achievements of Bill, his mentors and co-workers in this themed collection: the publications kindly dedicated to this celebratory themed collection serve to illustrate how far the field has come since the publication of a number of seminal results over 40 years ago.


Beginnings

Bill Kaska was born, raised and educated in Ancón, a suburb of Panama City, located in the then U.S.-controlled Canal Zone. He graduated from Loyola University in Los Angeles in 1957 and subsequently joined the group of Professor John J. Eisch at St. Louis University. Eisch had just returned to the United States from a post-doctoral position with Professor Karl Ziegler in Mülheim, Germany. Bill was one of Eisch’s first graduate students, charged with the task of investigating the then unexplored reactivity of alkyl and aryl aluminium compounds with unsaturated systems as alternatives to alkyl lithium reagents. Two years later, the Eisch group moved to The University of Michigan in Ann Arbor, and it was around this time that Kaska and Eisch published the first bona fide example of sp2 C‒H metalation using triphenyl aluminium.

After graduating from Michigan in 1963, Bill studied organoboron and organoberyllium compounds as a post-doctoral scholar in the laboratory of Professor Thomas Wartik at Penn State University. He was hired only one year later as an assistant professor at the newly-formed University of California at Santa Barbara, in the fall of 1964.

Notable contributions

The training Bill had gained during his formative graduate and post-doctoral years set him on the path to become a die-hard synthetic organometallic chemist; the type that refuses to believe that any structure that can be imagined and scribbled on the back of an envelope cannot also be made and isolated…somehow.

In his early years in Santa Barbara, Bill presented the first example of an organometallic Wittig reaction, demonstrated by the reaction of MnBr(CO)5 with (Ph3P2)C to afford a Mn=C=C=PPh3 ylide. Bill and his group later used (Ph3P)2C to prepare several other examples of acetylenic organometallic complexes. Notably, in a 1974 collaborative paper with R. F. Reichelderfer, it was shown that treatment of (COD)IrPF6 with (Ph3P)2C resulted in the oxidative addition of an sp3 C‒H bond of the coordinated cyclooctadiene ligand directly to the metal centre. This was the first example of a C‒H bond insertion of a coordinated ligand by a transition metal; it was not until the following decade that elegant work by Crabtree and several others elevated the profile of this powerful reaction type.

The hexaphenylcarbodiphosphorane species (Ph3P)2C used in Bill’s early chemistry had been discovered a decade earlier by Ramirez. The compound itself was found to exhibit triboluminescence, the mechanism and origin of which was not well understood at the time. Large yellow crystals of (Ph3P)2C grown from diglyme were found to emit a bright yellow-green light when touched. In 1977, Bill published a paper in collaboration with Jeffrey Zink (UCLA) that presented a detailed spectroscopic analysis of (Ph3P)2C and other aromatic triboluminescent materials. The conclusions of this study suggested that light emission was caused by a combination of frictional electrification, piezoelectrification, and internal electrification at shear planes within individual crystals.

In the late 1970s, Bill and his group had gained an interest in the use of what would come to be known as pincer ligands for the formation of coordinatively unsaturated complexes with bulky groups around the metal atom, as a way to promote C−H metalation of hydrocarbons. In 1980, at the Biennial Inorganic Chemistry Symposium in Guelph, Canada, Bill presented the X-ray structure and reactivity of a 14-electron Rh(I) PCP-pincer complex. The dehalogenated Rh(I) centre readily formed adducts with both aromatic and aliphatic hydrocarbons. The subsequent publication of this work included Craig Jensen as a co-author (now on the faculty at the University of Hawaii), who was an undergraduate student in Bill’s group at that time. A number of additional reports of the reactivity of other pincer complexes were published by Bill’s group shortly after, and this body of work forms an integral part of the early history of pincer chemistry.

For the next two decades, Bill worked alongside other major researchers, notably including Alan Goldman (Rutgers) and Gerard van Koten (Utrecht University) to further advance the chemistry of pincer complexes, which continues to attract significant attention to this day. The utility of pincer catalysts continues to break new ground. In 2001, the Kaska group published a communication in collaboration with Michael Hall (Texas A&M University) and Matthias Haenel (Max-Planck Institute) showing how a PCP-Ir(I) complex constructed using an “anthraphos” (1,8-substituted anthracene) ligand led to a thermally stable catalyst for alkane dehydrogenation.

In the later phase of Bill’s career, he gained an interest in the synthesis of proton sponge materials and super bases, using fused N-heterocyclic ligands based on quino[7,8-h]quinolines. In collaborative work with his long-time colleague at UCSB, Galen Stucky, and Ferdi Schüth (Max-Planck Institute), the first examples of transition metal coordination complexes of these so-called proton sponges were reported in 2001. These complexes were unusually thermally and chemically stable, due to the unique conformational bending of the qunioline backbone.

Over the past five decades, the Kaska lab has produced many highlight results in a number of fields of molecular inorganic chemistry. The works contributed to this celebratory compilation build upon the legacy of Bill Kaska’s work, his teaching, and his friendships with others in the community.

Articles in this themed collection

While this narrative is intended to summarise just a few of the highlights of Bill’s research career, his former Ph.D. mentor John Eisch has authored a terrific editorial entitled, “Emergence of electrophilic alumination as the counterpart of established nucleophilic lithiation: an academic sojourn in organometallics with William Kaska as a fellow traveler,” which provides a comprehensive, personal account of their seminal work in organoaluminium chemistry.

Research in the arena of C‒H bond activation has continued to attract much interest. This interest is driven not only by a fundamental curiosity to discover new chemical reactivity, but also to solve important energy-related problems involving hydrocarbon activation, in drug development, and in a host of other homogeneously-catalysed processes. This is abundantly clear from the new work on display in this themed collection.

In close relation to some of the seminal work published by Bill and his co-workers on the reaction chemistry of Group 9 PCP-pincer complexes, this themed collection features new work by Professors Alan Goldman, Karsten Krogh-Jesperson (University of Rochester) and co-workers, who present an elegant combined experimental and theoretical study of the C‒H versus C‒C bond activation selectivity observed between a PCP-Ir catalyst and biphenylene. They describe how and why biphenylene tends to initially undergo C‒H oxidative addition to the PCP-Ir centre, but upon heating can undergo a rearrangement that results in C‒C activation to yield a less sterically-hindered, cyclometallated species.

A collaborative experimental and theoretical study of an unusual PCP-Ir system is reported by the groups of Professors Johannes Wielandt (Karl-Franzens University) and Hermann Mayer (University of Tuebingen). They employ a cycloheptatriene-based PCP ligand scaffold; cyclometallation of this ligand with Ir(CO)3Cl requires activation of an sp3 C‒H bond. Upon standing in tetrahydrofuran, the complex undergoes isomerisation via transfer of the remaining sp3-H onto the ligand backbone. This results in three new isomers, each containing a more common sp2-metalated arrangement at Ir, and a partially saturated ligand backbone. Continuing the theme of cyclometallated Ir-based complexes, Professors Roy Periana, Brian Hashiguchi and co-workers from the Scripps Research Institute describe the use of a robust NNC-Ir complex that is active for the oxidation of methane, benzene and other hydrocarbons in the presence of trifluoroacetic acid.

Professor Gerard van Koten and co-workers describe a series of new NCN-Pt pincer complexes that feature 4-(E)-[(4-R-phenyl)imino] methyl substituents, which induce important electronic effects on the Pt(II) sites. A combination of multinuclear NMR studies have been used to elucidate the electronically-tuneable behaviour of this unique family of Pt-pincer complexes. The group of Professor Paul Hayes at the University of Lethbridge describe how Y and Sm complexes of their bis(phosphinimie) carbazolate and pyrrolate NNN-pincers undergo varying patterns of ortho-metalation toward N- and P-aryl substituents accompanied by reductive elimination of silanes.

This collection also features a number of examples of complexes based on neutral pincer ligands that display a range of C‒H bond activation reactivities. Professor Dan Mindiola and his team at the University of Pennsylvania present a PNP-Ti pincer complex capable of performing catalytic dehydrogenation of cyclic and linear alkanes to cleanly yield the corresponding alkenes. They elucidate a mechanism for this surprising reactivity, which involves the formation of a Ti(III) alkylidyne intermediate that can effect a double C‒H bond activation. The group of Professor Karen Goldberg at the University of Washington present the synthesis, structures and reactivities of PtMe2 complexes of a bidentate P(X)N ligand (X = O, NH). The N-donor pyridyl substituent is sufficiently hemilabilile to allow for cyclometallation and reductive elimination of CH4. Professor Michael Rose and his team at the University of Texas at Austin present a family of Mn-carbonyl complexes prepared using novel neutral NNS Schiff base ligands, in which the thioether-S donors also exhibits hemilability.

C‒H activation by early transition metal complexes also features in this collection; Professors John Arnold and Robert Bergman from the University of California demonstrate the cyclometallation of a (BDI)Ta(=NtBu)Me2 complex, which undergoes reaction with H2 gas to provide a dihydride intermediate by sigma-bond metathesis. Interestingly, a low-valent Ta(III) species is also generated under certain conditions, which undergoes C‒N bond cleavage of the BDI ligand to give a new Ta(V) cyclometallated species. Meanwhile, Professor Gerhard Erker and co-workers report the reaction of B(C6F5)3 toward zirconacycloallenoids. They show how strongly Lewis basic B(C6F5)3 species undergo insertion into the Zr metallacycles to give unusual zwitterionic allenyl/borate complexes.

Professor Manuel Soriaga and co-workers from Texas A&M University and the California Institute of Technology provide an example of heterogeneous C‒H bond activation and metalation, performed on solid Pd electrode surfaces. In this interesting and extensive study, high-resolution surface-sensitive techniques are combined with DFT calculations to elucidate the mechanism of metalation of 2,3-dimethylhydroquinone on ordered Pd(111) and polycrystalline Pd electrode surfaces. It is shown that the orientation of the quinone (side-on, or flat) as it undergoes oxidative chemisorption to the Pd surfaces is directly related to the relative quinone concentration.

Professor Carl Redshaw and collaborators from the Universities of Hull, Loughborough and East Anglia present the use of a family of new mono-, di- and tri-nuclear Zn(II)-calixarene complexes for the ring-opening polymerization of lactones and lactides. The group of Professor Dominic Wright at the University of Cambridge (where Bill Kaska spent a sabbatical in 2004) present the synthesis and crystal structures of an extended family of new ML2 sandwich complexes (M = Ca(II), Mn(II), Fe(II)), using a tripodal NNN monoanionic donor ligand (L = tris(2-pyridyl)aluminate).

The themed collection is nicely concluded by work from the group of Professor Bruce Lipshutz – a long-time friend and colleague of Bill Kaska in the Department of Chemistry & Biochemistry at UC Santa Barbara – who report the Cu(OAc)2-catalysed hydrophosphination of styrenes. Notably, this powerful organic conversion has been achieved under green conditions using water as the solvent, at room temperature; the reaction proceeds in high yield for a broad range of aromatic substrates.

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The 13th Ferrocene Colloquium

Dalton Transactions was proud to sponsor The 13th Ferrocene Colloquium, which took place from 22–24 February 2015 in Leipzig, Germany.

More than 120 participants, from Germany and from abroad, came to Leipzig to hear impressive talks and to present their latest results in the field.

The Colloquium also featured a poster session, which formed an integral part of the meeting, fostering the informal exchange of latest developments in this field of chemistry.

Congratulations to the participants and meeting organisers for making the Colloquium a great success!

The recipient of the award for the best oral presentation given by a young academic (postdoc)

The recipient of the Dalton Transactions award for
the best oral presentation given by a young academic (postdoc)

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March’s HOT articles

Take a look at HOT articles for March. These are only free to acess for 4 weeks only and are available for viewing in a collection on our website.

An ionic liquid process for mercury removal from natural gas
Mahpuzah Abai, Martin P. Atkins, Amiruddin Hassan, John D. Holbrey, Yongcheun Kuah, Peter Nockemann, Alexander A. Oliferenko, Natalia V. Plechkova, Syamzari Rafeen, Adam A. Rahman, Rafin Ramli, Shahidah M. Shariff, Kenneth R. Seddon, Geetha Srinivasan and Yiran Zou  
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C4DT03273J

Graphical Abstract

Free to access until 24th April 2015


Relationship between crystal structure and thermo-mechanical properties of kaolinite clay: beyond standard density functional theory
Philippe F. Weck, Eunja Kim and Carlos F. Jové-Colón 
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C5DT00590F

Graphical Abstract

Free to access until 23rd April 2015


The titanium tris-anilide cation [Ti(N[tBu]Ar)3]+ stabilized as its perfluoro-tetra-phenylborate salt: structural characterization and synthesis in connection with redox activity of 4,4′-bipyridine dititanium complexes
Heather A. Spinney, Christopher R. Clough and Christopher C. Cummins
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C5DT00105F

Graphical Abstract

Free to access until 14th April 2015


Iridium–bipyridine periodic mesoporous organosilica catalyzed direct C–H borylation using a pinacolborane
Yoshifumi Maegawa and Shinji Inagaki
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C5DT00239G

Graphical Abstract

Free to access until 14th April 2015

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A Cagey Conundrum

“My original intention in the late 1940s was to spend a few years understanding the boranes, and then to discover a systematic valence description of the vast numbers of electron deficient intermetallic compounds. I have made little progress toward this latter objective,” said the late Professor William N. Lipscomb in his 1976 Nobel acceptance speech.1

In their recent Dalton Transactions Hot Article, Jose M. Goicoechea and John E. McGrady examine the chemistry of main group cluster-encapsulated transition metal atoms, laying another piece of the foundation of Lipscomb’s “latter objective.”

The authors assign themselves an ambitious task: to provide a system to predict the geometries of cages of the tetrel elements (C, Si, Ge, Sn, Pb) which encapsulate transition metal atoms.  They focus on six high-symmetry cage structures, shown below, which have been observed for tetrel-encapsulated metal atoms (denoted M@Ex, for example Ni@Ge12.).

The six three-dimensional cage geometries examined.

Lipscomb’s elegantly-described closo, nido, and arachno borane structures (“closed,”“nest”, and “spider’s web,” respectively) provided an initial basis for classifications of cages.  Later, the Wade/Mingos rules laid the foundation for predicting the geometries based on the electronic structure of the cluster.

Goicoechea and McGrady use the total valence electron count –  of the tetrel cages, plus the d-electron count of the encapsulated metal – to describe patterns in the structures.  Nevertheless, some results defy electron-count classification, for example, the preference of silicon cages to form D6h-symmetric hexagonal prisms in M@Si12 complexes, in contrast to the M@Ge12 analogues.

It is a broad, big-picture paper, a synthesis of a wide range of experimental and theoretical results.  Some structures are known experimentally from x-ray crystallography, some have only been predicted computationally.  The authors discuss the varying relevance of considering the d-electron counts of the metals, and technological implications such as quenching of the magnetic moment of encapsulated metal atoms.  For me, the scope alone made this a worthwhile read.

Read the full article now:

On the structural landscape in endohedral silicon and germanium clusters, M@Si12 and M@Ge12
José M. Goicoechea and John E. McGrady
Dalton Trans., 2015, DOI: 10.1039/C4DT03573A

1 Lipscomb, W.N. “The Boranes and Their Relatives” in Les Prix Nobel en 1976. Imprimerie Royal PA Norstedt & Soner, Stockholm, 1977


Ian Mallov Ian Mallov is currently a Ph.D. student in Professor Doug Stephan’s group at the University of Toronto. His research is focused on synthesizing new Lewis-acidic compounds active in Frustrated Lewis Pair chemistry. He grew up in Truro, Nova Scotia and graduated from Dalhousie University and the University of Ottawa, and worked in chemical analysis in industry for three years before returning to grad school.
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Workshop on Flexibility and Disorder in Metal–Organic Frameworks

The Workshop on Flexibility and Disorder in Metal–Organic Frameworks will take place in Paris, France, from 3-5 June 2015.

Workshop on Flexibility and Disorder in Metal–Organic FrameworksOrganised by Anthony Cheetham (FRS), Alain Fuchs, Thomas Bennett, and François-Xavier Coudert, with funding from the European CECAM, as well as the French CNRS and Chimie ParisTech, this workshop will gather together distinguished speakers from a diverse range of disciplines to provide numerous viewpoints on topics including:

  • The Mechanical Behavior of MOFs
  • Amorphization and Nanostructures
  • Computational Approaches to Flexbility and Disorder
  • Defects and Disorder as Virtues

Further detail on the workshop’s aims and topics can be found here

Interested in this subject area? Submit your work to the Dalton Transactions themed issue on Flexibility and Disorder in Metal-Organic Frameworks: See our Call for papers and contact us for more information

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Call for papers: Themed issues

Dalton Transactions coverWe are delighted to announce four new Dalton Transactions themed issues:

Fluorine
Guest Editor: Professor Jennifer Love (University of British Columbia)
Deadline: 29th May 2015

Phosphorus Chemistry: Discoveries and Advances
Guest Editor: Professor Rory Waterman (University of Vermont)
Deadline: 11th August 2015

Flexibility and Disorder in Metal-Organic Frameworks
Guest Editors: Professor Anthony Cheetham (University of Cambridge), Professor Alain Fuchs (CNRS), Dr Thomas Bennett (University of Cambridge) and
Dr François-Xavier Coudert (CNRS & Chimie ParisTech)
Deadline: 8th September 2015

Main Group Transformations
Guest Editors: Professor Doug Stephan (University of Toronto) and Dr Rebecca Melen (Cardiff University)
Deadline: 6th October 2015

Does your research fit into any of these subject areas? If so, we would welcome your contribution. For further details on issue scopes and on how to submit, see below:

How to submit

All types of manuscript – communications, full papers and Perspectives, will be considered for publication. The manuscript should be prepared according to our article guidelines and submitted via our online system.

All manuscripts will be subject to normal peer review and inclusion in the themed issue will be at the discretion of the Guest Editors. Please indicate in your submission which themed issue you would like to be considered for.

Issue scopes

Fluorine
This issue will focus on all applications of fluorine in inorganic chemistry. Topics include, but are not limited to: organometallic and coordination complexes using fluorinated ligands, metal-catalysed and metal-mediated fluorination and C–F activation reactions, main group fluoride compounds, solid state metal fluorides, molecular fluoride complexes and materials for fluoride sensing and anion binding. Synthetic, theoretical, catalytic and mechanistic studies will all be suitable, as will any relevant studies on material properties.

Phosphorus Chemistry: Discoveries and Advances
The importance of phosphorus in diverse fields such as biomedicine, materials, energy, and catalysis is indisputable. Even as new applications for phosphorus-containing molecules and materials are realized, fundamental discoveries about the preparation, properties, and reactivity of phosphorus-containing compounds are still great advances. The goal of this issue is to showcase the diverse fundamental and applied science associated with phosphorus.

Flexibility and Disorder in Metal-Organic Frameworks
This themed issue will focus on the experimental characterization, fundamental understanding and computational modelling of the flexibility and/or disorder of metal–organic frameworks (MOFs), and other inorganic framework-type materials. It also encompasses the consequences of this flexibility for the proposed applications of MOFs, and the associated possibilities to leverage these properties to design novel materials with targeted properties. Key topics will include the influence of flexibility on the physical and chemical properties of MOFs, fundamental advances in the understanding of the behaviour of stimuli-responsive frameworks and characterization of disordered, defect-containing and amorphous materials.

Main Group Transformations
In recent years we have seen a renaissance in the field of main group chemistry, covering a diverse array of developments and potential applications in fields ranging from catalysis to molecular electronics. These have often evolved from studies in fundamental chemistry such as studies of the chemistry of low oxidation state and/or low coordination number compounds of the main group elements, fundamental studies in Lewis-acid/Lewis-base reactivity, main group heterocycles, free radicals and studies of the bonding in main group compounds.
This themed issue will focus on recent contributions from some of the leading researchers in the area, covering both fundamental and applications-driven research.

Interested in submitting  paper? Please contact us for more information

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Mercury-grabbing ionic liquids hit the gas

Written by Simon Neil for Chemistry World

Scientists in the UK and Malaysia have disclosed the research behind a fast and safe commercial technology for removing mercury from natural gas. The technology is the first solid-supported ionic liquid to be used at an industrial scale, and its development, from laboratory to full plant operation, took just four years.

The mercury-removing ionic liquid system was commercialised for use within the petroleum gas production industry

The mercury-removing ionic liquid system was commercialised for use within the petroleum gas production industry

The vast volume of natural gas that is processed annually by industry contains a pernicious contaminant – hundreds of tons of mercury. This corrosive metal is intrinsically present within hydrocarbon deposits, and it must be removed to mitigate catastrophic damage, not only to the environment but also to the gas-processing plants.

Interested? Read the full story at Chemistry World.

The link to the original article is below:

An ionic liquid process for mercury removal from natural gas
Mahpuzah Abai, Martin P. Atkins, Amiruddin Hassan, John D. Holbrey, Yongcheun Kuah, Peter Nockemann, Alexander A. Oliferenko, Natalia V. Plechkova, Syamzari Rafeen, Adam A. Rahman, Rafin Ramli, Shahidah M. Shariff, Kenneth R. Seddon, Geetha Srinivasan and Yiran Zou
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C4DT03273J

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A collection of papers in memory of Lord Jack Lewis

We are very pleased to announce the launch of a commemorative article collection in memory of Lord Jack Lewis.

Lord Jack Lewis, who recently died aged 86, was the 1970 Inorganic Professor at Cambridge for 25 years from 1970 to 1995. Highly energetic and extremely talented, he was among a small band of pioneers who revolutionised inorganic chemistry and must be regarded as one of the true founding fathers of the modern field. As a tribute to Jack, Brian F. G. Johnson, William. P. Griffith, Robin J. H. Clark, John Evans, Brian H. Robinson and Paul R. Raithby have chosen a selection of his papers that they feel demonstrate Jack’s interest and contribution to inorganic chemistry over the course of his career, introducing them in a special Editorial in Dalton Transactions.

We very much hope that you will enjoy this commemorative article collection.

To access all of the Lewis articles and the Editorial, go to: http://rsc.li/lewis.

Lord Jack Lewis

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February’s HOT articles

This month brings some more HOT articles. These are only free to acess for 4 weeks only and are available for viewing on our website.

Thermoelectric properties of the Zintl phases Yb5M2Sb6 (M = Al, Ga, In)
Umut Aydemir, Alex Zevalkink, Alim Ormeci, Heng Wang, Saneyuki Ohno, Sabah Bux and G. Jeffrey Snyder
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C4DT03773A

Graphical Abstract

Free to access until 25th March 2015


Exploring excited states of Pt(II) diimine catecholates for photoinduced charge separation
Paul A. Scattergood, Patricia Jesus, Harry Adams, Milan Delor, Igor V. Sazanovich, Hugh D. Burrows, Carlos Serpa and Julia A. Weinstein
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C4DT03466J

Graphical Abstract

Free to access until 25th March 2015


On the structural landscape in endohedral silicon and germanium clusters, M@Si12 and M@Ge12
José M. Goicoechea and John E. McGrady
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C4DT03573A

Graphical Abstract

Free to access until 9th March 2015


The synthesis, structure, topology and catalytic application of a novel cubane-based copper(II) metal–organic framework derived from a flexible amido tripodal acid
Anirban Karmakar, Clive L. Oliver, Somnath Roy and Lars Öhrström
Dalton Trans., 2015, Advance Article
DOI: 10.1039/C4DT03087G

Graphical Abstract

Free to access until 9th March 2015

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Bridging the gap – small ligands in MOFs

Posted on behalf of Christopher Hinde, web writer for Dalton Transactions

In a recent article from the group of Deanna D’Alessandro at the the University of Sydney, Australia, Liang et al. have shown for the first time a 3D metal-organic framework (MOF) comprised solely of the monocarboxylate ligand derived from formic acid, with exceptionally selective CO2 adsorption properties.

For those involved in MOF chemistry, it is well accepted that in most cases, organic bridging ligands should have at least two coordinating functional groups that link adjacent inorganic secondary building units into a porous crystalline lattice. Therefore, it comes as a complete surprise to find that a porous MOF can be formed entirely of monocarboxylate ligands that are traditionally used to cap and thus prevent further growth of the framework. Through structural characterisation, Liang et al. have shown that the formate takes on two different binding modes within the framework; one that caps the oxyzirconium cluster secondary building units, and another that bridges and interconnects these into a crystalline architecture.

Why is this important, I hear you ask? As the formate ligands are very small, this results in the formation of very small pores that can lead to selectivity in the adsorption of different gases. This is just what has been shown by Liang et al., with adsorption isotherms demonstrating that adsorption of CO2 is a factor of 145 higher than for N2. Potential applications may lead to the sequestration and use of greenhouses gases such as CO2 from the atmosphere.

CO2 and N2 isotherms for ZrFA

Check out the full article now!

The first example of a zirconium-oxide based metal–organic framework constructed from monocarboxylate ligands
Weibin Liang, Ravichandar Babarao, Michael J. Murphya and Deanna M. D’Alessandro
Dalton Trans., 2015, 44, 1516-1519


Christopher Hinde obtained his Masters degree in Chemistry from the University of Southampton, UK in 2011. He is currently doing research towards a Ph.D. in the area of materials chemistry and catalysis under the supervision of both Dr Robert Raja at the University of Southampton and Professor T. S. Andy Hor at the Institute of Materials Research and Engineering (IMRE), part of Singapore’s Agency for Science Technology and Research (A*STAR).
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