Metals and organic molecules are at the opposite sides in chemistry. Thus one may think that chemical bonding models, such as aromaticity, developed in organic chemistry will not be applicable in systems involving metallic elements. Yet in recent years there have been significant advances in extending the aromaticity and antiaromaticity concepts into the realm of metal clusters and alloys. These new developments have shown that aromaticity and antiaromaticity in metal systems have frequently multiple nature, being o-aromatic/antiaromatic and n-aromatic/antiaromatic, which is not found in organic aromatic/antiaromatic molecules.

http://casey.brown.edu/chemistry/research/LSWang/publications/209.pdf

All-Metal Aromaticity and Antiaromaticity

Clusters of main group elements are not rare. On the contrary, it is becoming difficult to avoid the discovery of new substances of this type. Clusters are the natural intermediate stages between an element and its isolated atoms or ions. In the form of polycations and polyanions they offer models for the stepwise oxidation and reduction of an element and represent a bridge between the elements. The great majority of homonuclear bonded structures are already present in the solid phases of simple systems. Mobilization of these clusters as molecules represents a great challenge.

Homoatomic Bonding of Main Group Elements

The chemistry of the p-block elements is a huge playground for fundamental and applied work. With their bonding from electron deficient to hypercoordinate and formally hypervalent, the p-block elements represent an area to find terra incognita. Often, the formation of cations that contain p-block elements as central ingredient is desired, for example to make a compound more Lewis acidic for an application or simply to prove an idea. This review has collected the reactive p-block cations (rPBC) with a comprehensive focus on those that have been published since the year 2000, but including the milestones and key citations of earlier work. We include an overview on the weakly coordinating anions (WCAs) used to stabilize the rPBC and give an overview to WCA selection, ionization strategies for rPBC-formation and finally list the rPBC ordered in their respective group from 13 to 18. However, typical, often more organic ion classes that constitute for example ionic liquids (imidazolium, ammonium, etc.) were omitted, as were those that do not fulfill the – naturally subjective – “reactive”-criterion of the rPBC. As a rule, we only included rPBC with crystal structure and only rarely refer to important cations published without crystal structure. This collection is intended for those who are simply interested what has been done or what is possible, as well as those who seek advice on preparative issues, up to people having a certain application in mind, where the knowledge on the existence of a rPBC that might play a role as an intermediate or active center may be useful.

/pdf/reactive-p-block-cations-stabilized-by-weakly-coordinating-3fdr6dqet4.pdf

Reactive p-block cations stabilized by weakly coordinating anions

Soluble selenides and tellurides

Cluster der Hauptgruppenelemente sind keine Raritat; vielmehr werden immer neue Spezies dieses Typs gefunden. Die Cluster sind die naturlichen Stufen zwischen einem Element und seinen isolierten Atomen oder Ionen. Sie bieten als Polykationen und Polyanionen auch Modelle fur die schrittweise Oxidation und Reduktion eines Elements und bilden die Brucke zwischen den Elementen. Die grose Mehrheit homonuclear verknupfter Strukturen kommt in den festen Phasen einfacher Systeme vor. Sie in molekularer Form zu mobilisieren, bedeutet eine grose Herausforderung.

Thomas W. Couch

Papers

Crystal structures of tetratellurium(2+) tetrachloroaluminate and heptachlorodialuminate, Te42+(AlCl4-)2 and Te42+(Al2Cl7-)2

Magnetism and spectroscopy of a series of hexafluorotitanates(III)

Kristallstrukturen von tetratellurtetrachloroaluminat und -heptachlorodialuminat, te4(2+)(alcl4)2 und te4(2+)(al2cl7)2