Ute Weber

Nackte hauptgruppenelemente als trigonal planar gebundene μ3-brückenliganden

Abstract In (LnM)2X-Hal compounds which contain a trigonally planar coordinated bridging element (X = P, As, Sb) stabilized by two 16-electron LnM fragments the halogen may be substituted by monovalent organometallic groups. In the resulting molecules the bridging X atoms are coordinated to three metal atoms in a trigonal planar fashion. The syntheses and properties of 12 species of this type (I–IX) are described. The reaction of Na2W2(CO)10 with XCl4 (X = Ge, Sn) leads to [(Co)5W]3(μ3-X) compounds containing trigonally planar coordinated Ge (X) and Sn (XI), respectively. The trigonal planar coordination of the Main Group elements X is confirmed by eight X-ray analyses.

Diphosphor, phosphor-, arsen- und antimonatome als clusterbaugruppen

Abstract Reactions of Fe2(CO)9 with LnMPHal3 (LnM = 16-electron fragment: Cp(CO)2Mn, (CO)5Cr, (CO)5Mo, (CO)5W) yield clusters of the type F3(CO)9(μ4-P)2(MLn)2 (II). Compounds II contain the trigonal bipyramidal cluster framework Fe3(CO)9(μ3-P)2, the basis of which is a closed triangle formed by three Fe(CO)3 units; the apical positions of the trigonal bipyramid are occupied by phosphorus atoms. Each of the capping phosphorus atoms binds an additional MLn fragment. Compounds of type II are also obtained from Fe2(CO)6(μ3-P)2(MLn)2 (I) by formal addition of an Fe(CO)3 group. A further general synthetic approach to clusters Fe3(CO)9(μ4-X)2 (MLn)2 (X = P, As, Sb) is the reaction of halo-phosphinidene, arsinidene or stibinidene complexes, (LnM)2XHal (X = P, As, Sb) with Na2Fe(CO)4. Similar procedures are used for the construction of compounds III and IV. Complexes III contain phosphorus as a μ4-spiro centre; compounds IV contain metallacyclic phosphanes (CO)4 FeP(R)Fe (CO)4 as ligands. From (CO)5CrPBr3 and Fe2(CO)9 the cluster Fe2(CO)7(PP)[Cr(CO)5]2 (V) is obtained in which a diphosphorus unit is side-on and end-on coordinated as an eight-electron ligand. The identity of the new compounds is documented by analytic and spectroscopic data as well as by X-ray-structure analyses of seven compounds.

Stibinidenkomplexe: Verbindungen mit trigonal planar koordiniertem antimon

Abstract Intensively coloured stibinidene complexes (LnM)2SbR (LnM = (CO)5Cr; R = tBu, Cl, I, EtS. LnM = C5H5(CO)2Mn; R = Cl. LnM = CH3C5H4(CO)2Mn; R = Br) which contain trigonally planar coordinated Sb(+1) with the stibanediyl ligand stabilized by M ⋯ Sb(R) ⋯ M-π-bonding have been obtained. Their synthesis and properties as well as an X-ray structure determination of [CH3C5H4(CO)2Mn]2SbBr are described.

Valenztautomerie an stibiniden-komplexen. Synthese von stiban und distiben-komplexen

Abstract The reaction of RSbCl 2 with Na 2 W 2 (CO) 10 gives the stibinidene intermediates RSb[W(CO) 5 ] 2 . These intermediates react with Lewis bases (B|) to give the adducts BSb(R)[W(CO) 5 ] 2 , with Lewis acids, such as (CO) 5 W, they give the trinuclear species RSb[W(CO) 5 ] 3 . These results indicate a valence tautomerism with the species (CO) 5 WSb(R)W(CO) 5 acting as a Lewis acid and the species as a Lewis base. The synthesis of stibinidene complexes is often accompanied by the formation of distibene complexes [RSb=SbR][W(CO) 5 ] 3 . This type of reaction is illustrated by four examples and discussed in terms of the above model of valence tautomerism. One example of the conversion of distibene complexes into derivatives of stibinidene complexes is given. The novel compounds are characterised by standard physicochemical methods including X-ray structure analyses.

Bi2, das Bismuth-Homologe des Distickstoffs als Komplexligand in Bi2[W(CO)5]3 / Bi2, the Bismuth Homologue of Dinitrogen as a Ligand in Bi2[W(CO)5]3

Abstract Reductive dehalogenation of BiCl3 with Na2W2(CO)10 leads to Bi2[W(CO)5]3 (1), which contains an axial Bi2 ligand side-on coordinated to three W(CO)5 groups. The star-type arrangement of three metal carbonyl moieties around a Bi2 axis with a very short Bi-Bi bond distance (281.8(3) pm) and a Bi2W3 core of approximate D3h symmetry is proved by an X-ray analysis (R1 = 0.041). 1 is thus the highest homologue of a series of complexes X2[W(CO)5]3 (X = As, Sb, Bi) and is the first stable molecular compound to contain a Bi2 ligand.

Phosphiniden-, Arsiniden- und Stibiniden-Komplexe, ihre valenztautomeren Formen und Dimerisierungsprodukte/Phosphinidene-, Arsinidene- and Stibinidene Complexes, Valence Tautomerism and Dimerisation Products

Compounds RXHal2 (X = P, As, Sb) react with Na2[M2(CO)10] (M = Cr, Mo, W) to yield three types of products: A, [(CO)5M]2X-R containing trigonally planar coordinated X; C, [(CO)5M]3X-R containing coordinated metallacyclic ligands; B, [xxx] D, [(CO)5M]n (R)X = X (R) (n = 0, 1, 2, 3). The relation between these species, especially the one based on the valence tautomerism between A und B, is experimentally verified. Preparative, spectroscopic and X-Ray-structural results reveal a consistent picture of the relevant chemistry.

Synthesen und Strukturen von Distibankomplexen / Syntheses and Structures of Distibane Complexes

Stibanes RSbHal2 are reductivly coupled by interaction with Na2M2(CO)10 (M = Cr, W) or Cp(CO)2MnTHF. The resulting distibanes RS̲b̲(Hal)-(Hal)S̲b̲R are coordinated to sixteen electron LnM-fragments (LnM=M(CO)5, Cp(CO)2Mn). Both the meso and d/l stereoisomeres are structurally characterised by X-ray analyses.