Six FeIII centers are incorporated into the tungstophosphate anion [H2P2W12O48]12− upon reaction with FeCl3. The {P2W12Fe6} unit thus formed has been characterized in [H4P2W12Fe9O56(OAc)7]6− and [H56P8W48Fe28O248]28−. The latter is a supramolecular polyoxotungstate in which each of the four {P2W12Fe6} units is connected by three Fe‐O‐Fe bridges (see structure). Magnetic studies indicate strong antiferromagnetic coupling between the FeIII centers.

The regioselectivity of the Heck reaction is supposed to be highly affected by the electronic properties of the alkene and the ionic or neutral character of the aryl palladium(II) complexes involved in the reaction with alkenes. In Heck reactions performed in dmf, [Pd(dppp){dppp(O)}Ph](+) (dppp=1,2-bis(diphenylphosphino)propane) is generated in the oxidative addition of PhI with [Pd(0)(dppp)(OAc)](-) formed in situ from Pd(OAc)(2) associated to two equivalents of dppp. [Pd(dppp){dppp(O)}Ph](+) is not very reactive with alkenes (styrene or methyl acrylate); however, it reacts with iodide ions (released in the catalytic reactions) to give [Pd(dppp)IPh] and with acetate ions (used as base) to give [Pd(dppp)(OAc)Ph]. [Pd(dppp)(OAc)Ph] reacts with styrene and methyl acrylate exclusively by an ionic mechanism, that is, via the cationic complex [Pd(dppp)(dmf)Ph](+) formed by dissociation of the acetate ion. The reaction of [Pd(dppp)IPh] is more complex and substrate dependent. It reacts with styrene exclusively by the ionic mechanism via [Pd(dppp)(dmf)Ph](+). [Pd(dppp)IPh] (neutral mechanism) and [Pd(dppp)(dmf)Ph](+) (ionic mechanism) react in parallel with methyl acrylate. [Pd(dppp)(dmf)Ph](+) is more reactive than [Pd(dppp)IPh] but is always generated at lower concentration.

Two main intermediate complexes, PhPd(OAc)(dppp) and PhPdI(dppp), are generated in palladiumcatalyzed Heck reactions performed from PhI and an acetate salt used as a base, in DMF. Both complexes react with the electron-rich alkene isobutyl vinyl ether (CH 2 dCHO i Bu) exclusively by an ionic mechanism, i.e., via the cationic complex [PhPd(dppp)(DMF)] + formed by dissociation of AcOor Ifrom the parent complexes, as already established for the reaction of PhPd(OAc)(dppp) with styrene and methyl acrylate and the reaction of PhPdI(dppp) with styrene. A mechanism is proposed which rationalizes the regioselectivity observed when reacting the electron-rich isobutylvinyl ether in palladium-catalyzed Heck reactions.

Clusters which display the rare cubic Fe8 topology have been obtained by reaction of the metastable hexavacant polyoxotungstate [H2P2W12O48]12- with basic trinuclear metal acetates.

Sechs FeIII‐Zentren eingebaut: Das Wolframophosphatanion [H2P2W12O48]12− bildet mit FeCl3 {P2W12Fe6}‐Einheiten, die in [H4P2W12Fe9O56(OAc)7]6− und [H56P8W48Fe28O248]28− charakterisiert wurden. Letzteres ist ein supramolekulares Polyoxowolframat, in dem jede der vier {P2W12Fe6}‐Einheiten durch drei Fe‐O‐Fe‐Brücken verknüpft ist (siehe Struktur). Magnetismusstudien weisen auf eine starke antiferromagnetische Kopplung zwischen den FeIII‐Zentren hin.

The rate constants of the oxidative addition of the transition-metal iodocyclopentadienyl complexes (η5-C5H4-I)MLn (ML n = Mn(CO)3 (1a), Re(CO)3 (1b), CpFe (1c)) with Pd0(PPh3)4 have been determined in DMF. As expected, the oxidative addition is faster for the electron-acceptor groups Mn(CO)3 and Re(CO)3 than for the electron-donor group FeCp, with the reactivity order 1a > 1b ≫ 1c. Comparison of the rate constants of the oxidative additions affords a new strategy for the evaluation of the electronic properties of transition-metal units ligated to the iodocyclopentadienyl moiety with the following decreasing electron-acceptor properties:  Mn(CO)3 > Re(CO)3 ≫ FeCp. The complexes formed in the oxidative addition are characterized as trans-[(η5-C5H4)PdI(PPh3)2]ML n (ML n = Mn(CO)3 (2a), Re(CO)3 (2b), CpFe (2c)) with the decreasing stability order in DMF:  2c ≫ 2b > 2a. The relevance to the efficiency of palladium-catalyzed Stille or Sonogashira reactions from related complexes 1 is discussed.

As revealed by single crystal XRD compound (IV) crystallizes in the monoclinic space group C2/c. Its structure derives from the hexavacant α-[H2P2W12O48] 12anion by filling up the six vacancies with Fe atoms. The substituted Wells-Dawson species {P 2 W 12 Fe 6 } thus formed supports three additional Fe atoms. Because the quality of the crystals of (VI) is not suitable for single crystal XRD, crystals of (VIII) are used for the structure determination. Na16K10[H55P8W49Fe27O248]·90H2O crystallizes in the triclinic space group P1. This cluster with 27 Fe III centers, is the second largest iron cluster characterized so far. - (GODIN, B.; CHEN, Y.-G.; VAISSERMANN, J.; RUHLMANN, L.; VERDAGUER, M.; GOUZERH*, P.; Angew. Chem., Int. Ed. 44 (2005) 20, 3072-3075; Lab. Chim. Inorg. Materiaux Mol., CNRS, Univ. P. et M. Curie, F-75252 Paris, Fr.; Eng.) -W. Pewestorf 32-031

Compound (IV) (yield given in g) crystallizes in the triclinic space group P1 with Z = 1 and compound (VI) in the monoclinic space group P21/c with Z = 2, as revealed by single crystal XRD. Both compounds display the rare cubic Fe 8 topology. -(GODIN, B.; VAISSERMANN, J.; HERSON, P.; RUHLMANN, L.; VERDAGUER, M.; GOUZERH*, P.; Chem. Commun. (Cambridge) 2005, 45, 5624-5626; Lab. Chim. Inorg. Materiaux Mol., CNRS, Univ. P. et M. Curie, F-75252 Paris, Fr.; Eng.) -W. Pewestorf 09-033