For a long time, Zintl ions of Group 14 and 15 elements were considered to be remarkable species domiciled in solid-state chemistry that have unexpected stoichiometries and fascinating structures, but were of limited relevance The revival of Zintl ions was heralded by the observation that these species, preformed in solid-state Zintl phases, can be extracted from the lattice of the solids and dissolved in appropriate solvents, and thus become available as reactants and building blocks in solution chemistry The recent upsurge of research activity in this fast-growing field has now provided a rich plethora of new compounds, for example by substitution of these Zintl ions with organic groups and organometallic fragments, by oxidative coupling reactions leading to dimers, oligomers, or polymers, or by the inclusion of metal atoms under formation of endohedral cluster species and intermetalloid compounds; some of these species have good prospects in applications in materials science This Review presents the enormous progress that has been made in Zintl ion chemistry with an emphasis on syntheses, properties, structures, and theoretical treatments

Zintl ions, cage compounds, and intermetalloid clusters of Group 14 and Group 15 elements.

An overview about the activation of white phosphorus, P4 with main group elements and compounds is given.

P4 Activation by Main Group Elements and Compounds

The coordination chemistry of white phosphorus is nowadays a mature discipline, which during the last four decades has reached a deep understanding of the mechanisms governing the metal-mediated activation of this unique and highly reactive molecule. The birth certificate of this story dates back to 1970 when the synthesis of [RhCl(PPh3)2(η-P4)] together with other rhodium and iridium species was reported by Ginsberg and Lindsell as a short communication in Transactions of the New York Academy of Sciences.1,2 Immediately, this seminal discovery motivated intense research activity worldwide. Worth mentioning among the pioneers in this area are the groups led by Markó in Veszprem, Hungary; Dahl in Madison, Wisconsin, U.S.A.; and Sacconi in Florence, Italy. While the first two demonstrated that fragments deriving from P4 degradation could be stabilized as ligands in the coordination sphere of cobalt carbonyl3 and cyclopentadienyl derivatives,4 Sacconi first succeeded in coordinating the intact tetrahedral P4 molecule to a metal,5 obtaining the Ni(0) complex [(κ-P,P,P-NP3)Ni(ηP4)], and in fully characterizing a vast family of cyclo-P3 late transition metal derivatives spanning from iron to osmium.6 In the following decade, the development of the isolobal concept7 and its application to organometallic and main group chemistry paved the way to the synthesis of an incredible variety of polyphosphorus architectures where CH, CH2, and CH3 fragments in acyclic and cyclic hydrocarbons could be formally replaced by naked P atoms and substituted PH and PH2 units, respectively. Spectacular examples of organometallic phosphorus topologies ruled by the isolobal relationship can be found in the systematic work done in Kaiserslautern by Scherer and his co-workers who applied the isolobal P T C-H relation to the synthesis of a myriad of polycyclic phosphorus species mimicking benzene and other arenes. Landmarks in this area were the discovery of the cyclo-P6 ligand stabilized as internal layer in the triple-decker dimolybdenum complex [{Cp*Mo}2(μ,η-P6)] and the pentaphosphaferrocene derivative [{Cp*Fe}(η-P5)]. These species, within the loose boundaries of the isolobal concept, may be considered as the all-phosphorus analogues of benzene and cyclopentadienyl anion, respectively. The intriguing analogy between hydrocarbon species and organophosphorus compounds has been reviewed in the successful book “Phosphorus: The Carbon Copy” published by Wiley in 1998.10 In the last two decades, several reviews have also appeared covering different aspects of transition metalmediated white phosphorus activation. These include specific surveys addressing the formation of P-H11 and P-C species12 as well as some general reviews targeting the synthesis and the characterization of transition metal complexes incorporating naked phosphorus atoms and units as ligands.13-17 The importance of studying the coordination chemistry of elemental phosphorus by late (and early) transition metal complexes also stems from the need to replace the current technology for the production of organophosphorus derivatives. This reaction, which is of great industrial relevance, is still based on the chlorination of white phosphorus followed by the reaction of PCl3, PCl5, or POCl3 with the † This contribution is dedicated to our colleague and friend Prof. Piero Stoppioni on occasion of his 65th birthday and in recognition of his outstanding achievements in the field of white phosphorus activation. ‡ Note: In figures showing X-ray crystal structures, H atoms are generally omitted for clarity unless specified. * To whom correspondence should be addressed. E-mail: mperuzzini@ iccom.cnr.it. Chem. Rev. 2010, 110, 4178–4235 4178

P4 Activation by Late-Transition Metal Complexes†‡

Plant polyphenols (vegetable tannins): gallic acid metabolism

Pn and Asn Ligands: A Novel Chapter in the Chemistry of Phosphorus and Arsenic

The complexchemisty of “nacked” Ex-unites (E = P, As, Sb, Bi; x = 1–6) has developed rapidly since the end of the seventies. Most of the Ex-groups, except P4, are unstable in the free state but can be stabilized by complexation with transition metal fragments. They are isolobal to the corresponding (CH)x-arrangements. This article gives a comprehensive review of this young and dynamic field of chemistry up to 1988. It generalizes methods of synthesis, compares modes of coordination and types of polyeders of these complexes. The article describes the analogies and differences in the coordination behaviour of “nacked” Ex-groups of phosphorus, arsenic, antimony and bismuth. Thus, there is an anomaly of bismuthine complexes by reason of the metallic character of Bi.

Koordinationschemische Stabilisierung "nackter" Elemente der V. Hauptgruppe (außer Stickstoff) - Synthese, Struktur und Bindung

White phosphorus and a suitable metal complex fragment are always good for surprises. Reaction of [W(CO)5thf] with P4 in THF affords the complex shown on the right, in which the square-planar P4 ligand serves as a 12-electron donor. The analogous chromium complex is also accessible in this way.

Eckhard Herrmann

Papers

Koordinationschemische Stabilisierung "nackter" Elemente der V. Hauptgruppe (außer Stickstoff) - Synthese, Struktur und Bindung

The cyclo‐P4 Ligand as 12‐Electron Donor

The cyclo-P4 Ligand as 12-Electron Donor [Der cyclo-P4-Ligand als 12-Elektronen-Donor]

Der Cyclo-P4-ligand als 12-Elektronen-Donor

Extraction of scandium with tetraphenyl imidodiphosphate and its sulfur analogues, and the radiation stability of the reagent