Beate Sigwarth

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.

μ3-P- und μ3-As-verbrückte cluster als liganden

Abstract The trihalophosphane complexes LnMPHal3 (LnM = Cp(CO)2Mn, (CO)5Cr, (CO)5W; Hal = Cl, Br), upon treatment with Co2(CO)8, mainly yield clusters of the type Co3(CO)9(μ4-P)MLn with the (μ3-P)Co3(CO)9) unit acting as ligand. The analogous arsenic compound Co3(CO)9(μ4-As)Cr(CO)5 is obtained from the arsinidine complex [(CO)5Cr]2AsCl with NaCo(CO)4. In addition to the syntheses and reactios of these clusters several reactions leading to clusters with μ4-P-, μ4-As-, μ4-PR- and μ2-PR2 groups by reductive dehalogenation of coordinated halophosphanes are reported. The different types of compounds are documented by six X-ray-structure 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.

Stabilisation of [Fe2(CO)9] and [Ru2(CO)9] bu substitution with bridging diphosphorus ligands

Abstract Reaction of [Fe 2 (CO) 9 ] with a half molar amount of R 2 PYPR 2 (Y = CH 2 , R = Ph, Me, OMe or OPr i ; Y = N(Et), R = OPh, OMe or OCH 2 ; Y = N(Me), R = OPr i or OEt) leads to the ready formation of a product which on irradiation with ultraviolet light rapidly decarbonylates to the heptacarbonyl derivative [Fe 2 (μ-CO)(CO) 6 {μ-R 2 PYPR 2 }]. Treatment of the latter with a slight excess of the appropriate ligand results, under photochemical conditions, in the formation of the dinuclear pentacarbonyl complex [Fe 2 (μ-CO)(C)) 4 {μ-R 2 PYPR 2 } 2 ] but under thermal conditions in the formation of the mononuclear species [Fe(CO) 3 {R 2 PYPR 2 }]. Reaction of [Ru 3 (CO) 12 ] with an equimolar amount of (RO) 2 PN(R′)P(OR) 2 (R′ = Me, R = Pr i or Et; R′ = Et, R = Ph or Me) under either thermal or photochemical conditions produces [Ru 3 (CO) 10 {μ-(RO) 2 PN(OR) 2 }] which reacts further with excess (RO) 2 PN(R′)P(OR) 2 on irradiation with ultraviolet light to afford the dinuclear compound [Ru 2 (μ-CO)(CO 4 {μ-(RO) 2 PN(R′)P(OR) 2 } 2 ]. The molecular structure of [Ru 2 (μ-CO)(CO) 4 {μ-(MeO) 2 PN(Et)P(OMe) 2 } 2 ], which has been determined by X-ray crystallography, is described.

Diarsen, As2, als side on gebundener sechs-elektronen-ligand

Abstract The compound As2[W(CO)5]3 is obtained from AsCl3 and Na2W2(CO)10 or (CO)5 WTHF respectively. Its wheel-type molecular framework as determined by X-ray analysis has D3h symmetry with three W(CO)5 groups surrounding the axial As2 ligand (d(AsAs) = 227.9 pm) which thus acts as a six-electron donor. This unusual bonding situation is analysed by EHT methods.

Alkylarsinidenkomplexe und arsinidenkomplexe mit verschiedenen metallen

Abstract The chloroarsinidene complexes (CO)5Cr⎓As(Cl)⎓Cr(CO)5 (I) and Cp(CO)2-Mn⎓As(Cl)⎓Mn(CO)2Cp (III) react with R3Al (R ⎓ alkyl, aryl) to give (CO)5Cr⎓As(R)⎓Cr(CO)5 (II) and Cp(CO)2Mn⎓As(R)⎓Mn(CO)2Cp (IV), respectively. The alkylarsinidene complexes obtained in this way for the first time are intensely coloured crystalline compounds, which contain trigonally planar coordinated arsenic(I) as shown by X-ray analysis of i-C4H9As[Cr(CO)5]2 (IIb). Reaction of Na2M2(CO)10 with RAsCl2 (R ⎓ alkyl; M ⎓ Cr, W) is another route to the alkylarsinidene compounds RAs[M(CO)5]2. Similarly AsCl3 and Na2Cr2(CO)10 react to give the chloroarsinidene complex I. The heterometallic arsinidene complex (CO)5Cr⎓As(Cl)⎓Mn(CO)2Cp (VIII) is obtained by thermally induced comproportionation from I and III. Like other chloroarsinidene complexes it reacts with tropolone to give an arsenic(I) chelate (IXa) stabilized by complexation. The structure of IXa has been determined by X-ray methods. In the presence of a base reaction of VIII with water leads to [(CO)5Cr] [Cp(CO)2Mn]AsOAs[Mn(CO)2Cp] [Cr(CO)5] (Xa). Under similar conditions I and III give analogous homometallic derivatives of As2O, an arsenic(I) oxide, not known in the free state. An X-ray analysis of [MeCp(CO)2Mn]2AsOAs[Mn(CO)2CpMe]2 (Xb) shows that in compounds X both arsenic atoms have a trigonal planar configuration. The arsenic atoms in X are thus coordinatively unsaturated and will add Lewis bases to give adducts like [(CO)5Cr]2As(PPh3)OAs(PPh3)[Cr(CO)5]2 (XI).

Reduction products of dinuclear [Rh2Cl2(CO)2 {μ-(PhO)2PN(Et)P(OPh)2}2]. Crystal structure of [Rh2HgCl(μ-H)(CO)2 {μ-(PhO)2PN(Et)P(OPh)2}2]

Abstract Treatment of [Rh 2 Cl 2 (CO) 2 {μ-(PhO) 2 PN(Et)P(OPh) 2 } 2 ] with various reducing agents gives a number of products, the type depending on the conditions employed. The products isolated include [Rh 2 (CO) 2 {μ-(PhO) 2 PN(Et)P(OPh) 2 } 2 ], [Rh 2 (CO) 3 {μ-(PhO) 2 PN(Et)P(OPh) 2 } 2 ],and [Rh 2 HgCl(μ-H)(CO) 2 {μ-(PhO) 2 PN(Et)P(OPh) 2 } 2 ]; the structure of the last complex was determined by X-ray diffraction.

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.