Simon Cotton

Lanthanides and actinides

Scandium - Yttritium and the Lanthanides - Actinides - Chemistry of the Elements - Bibliography - Index

Unequivocal characterisation of a [Ln(terpy)(NO3)3.(H2O)] complex. The synthesis and structure of [M(terpy)(NO3)3.(H2O)] (M = Eu, Tb); a comparison with the structure of [Eu(bipy)2(NO3)3] and with other europium nitrate complexes {terpy = 2,2' :6', 2 -terpyridyl; bipy = 2,2'-bipyridyl}

Abstract The complexes [M(terpy)(NO3)3·(H2O)] (M=Eu (1), Tb(2); terpy=2,2′:6′,2″-terpyridyl) are isomorphous and crystallise in the triclinic space group P 1 with Z=2, while the related complex [Eu(bipy)2(NO3)3] (3) (bipy=2,2′-bipyridyl) crystallises in the orthorhombic space group Pcan (non-standard setting of Pbcn) with Z=4 such that the two halves of the molecule are related by a crystallographic twofold axis. In each of the three complexes the metal atom is 10 co-ordinate and all three contain three bidentate nitrate groups. In complexes 1 and 2 the coordination sphere is completed by the three nitrogen donor atoms of the terpyridine ligand and by the oxygen donor atom of the coordinated water solvent molecule. In complex 3 the coordination sphere is completed by two nitrogen donor atoms from each of the two bipyridine ligands. These structures are compared with other lanthanide complexes of related ligands and the factors affecting the co-ordination geometry evaluated.

Praseodymium complexes of 2,2′-bipyridine; the crystal and molecular structures of Pr(bipy)3(NCS)3, Pr(bipy)2(NO3)3, Pr(bipy)2Cl3(OH2)·EtOH and Pr(bipy)(S2CNEt2)3

Abstract The structures of Pr(bipy)3(NCS)3, Pr(bipy)2(NO3)3, Pr(bipy)2Cl3(OH2)·EtOH and Pr(bipy)(S2CNEt2)3 are reported. Pr(bipy)3(NCS)3 has a monomeric structure with three N-bonded thiocyanates and three bidentate bipyridyl ligands, giving nine-coordinate praseodymium. Praseodymium is eight-coordinate in Pr(bipy)2Cl3(OH2)·EtOH and in Pr(bipy)(S2CNEt2)3 whilst Pr(bipy)2(NO3)3 is isostructural with the La, Nd and Lu analogues, having three bidentate nitrates and two bipyridyl ligands, affording 10-coordinate praseodymium. Factors affecting bond lengths in the compounds are discussed.

Iron, cobalt and nickel

Areas of particular interest this year include further advances in non-haem iron(IV)oxo species, continued activity in five coordinate iron and cobalt polymerisation catalysts and the first example of a spin-crossover compound where the two iron atoms are trapped in different spin states. There is a considerable upsurge in nitrosyl chemistry.

The synthesis and structure of [Er(terpy)(NO3)3·(C2H5OH)]; an example of preference for monodentate over bidentate coordination for the nitrate group

Abstract Erbium is nine-coordinate in [Er(terpy)(NO 3 ) 3 ·(C 2 H 5 OH)], which contains two bidentate and one monodentate nitrate groups as well as a coordinated ethanol molecule.

Benchmark compounds. Structures of cobalt(II) complexes of triphenylphosphine- and triphenylarsine oxides

The structures of the Co(OPPh3)2Cl2, Co(OPPh3)2Br2, Co(OPPh3)2I2, Co(OAsPh3)2Br2 and Co(OAsPh3)2(NO3)2 complexes have been determined by X-ray diffraction methods; all have pseudo-tetrahedral co-ordination for cobalt.

SCANDIUM, YTTRIUM, THE LANTHANIDES AND THE ACTINIDES

Highlights include a tris(pentamethylcyclopentadienyl)uranium(dinitrogen) complex; the characterization of the hitherto shadowy uranyl iodide as the etherate UO2I2(OH2)2·4Et2O; a remarkable uranyl(V) species, [UO2(OPPh3)4](OTf); a detailed analysis of agostic interactions in the pyramidal amides [Ln{(N(SiMe3)2)3}] and alkyls [Ln{(CH(SiMe3)2)3}]; increased interest in lanthanide alkyls, both cationic and neutral; and the variety of co-ordination chemistry of the lanthanides with terdentate N-donors.

Bis(2,2′-bipyridyl-N,N′)­tris­(nitrato-O,O′)­neodymium

The title compound, [Nd(bipy-N,N′)2(NO3–O,O′)3], is found to be isomorphous with the La and Lu analogues having three bidentate nitrate and two bipyridyl ligands giving a ten co-ordinate environment.

Titanium, zirconium and hafnium

This chapter reviews the literature reported during 2007 on titanium, zirconium and hafnium. Because of the limitations of space, this review is very selective, and much fine work has not been cited, especially in the area of organometallic chemistry.

Technetium and Rhenium

These two metals are less well known than many other of the second- and third-row transition metals, although interest in rhenium chemistry has recently increased. Technetium, as its name suggests, is an artifically produced element, the only such among all the d transition metals. It is thus not an element of which the majority of chemists have any direct experimental knowledge. Rhenium is a relatively rare element with few uses but with several interesting features, for example its unusual complex hydrides. These metals mark the half-way stage in the progression along the transition-metal series. The stability of the d5 Mn2 + ion is not reflected in Tc2 + and Re2 +, however; the heavier metals, as usual, are more stable in higher oxidation states.