Joachim Fuchs

New C-tetrazolato complexes of rhodium(III), palladium(II) and gold(III)

Abstract The azido complexes [RhCp*(μ-N3)(N3)]2 (Cp*=η-C5Me5), trans-Rh(N3)(CO)(PPh3)2, Na2[Pd(N3)4], Na2[Pd2(μ-N3)2(N3)4] and Na[Au(N3)4], prepared in situ from metal halide precursors and a three- to ten-fold excess of NaN3 in water, react with aliphatic isocyanides to give a series of new metal–carbon bonded tetrazolato complexes. All azide ligands in the coordination sphere undergo this cycloaddition with isocyanides except on palladium(II) where only two tetrazol-5-ato groups are formed. In the neutral species HAu(CN4R)4 (R=tBu (2c), Cy (2d)) presumably one of the four tetrazol-5-ato groups has been protonated to afford a tetrazol-5-ylidene (carbene) ligand. The reactivities of the isocyanides decrease in the order CNtBu>CNCy>CN(CH2)4Cl>CN-allyl>CNCH2CO2Na; surprisingly, no reaction occurs with methylisocyanide. With tert-butyl isocyanide in the cold, [Ru(μ-N3)(N3)(η-C10H14)]2 (C10H14:4-isopropyltoluene) only reacts with cleavage of the azido bridges giving rise to [Ru(N3)2(η-C10H14)CNtBu] (5a), while heating of the same mixture affords a second azido-isocyanide complex, trans-[Ru(N3)2(CNtBu)4] (5b), of which an X-ray structure analysis has been carried out. In some cases the reactions proceed with N2 evolution, and rhodium complexes 6a–c are also formed probably containing cyanamido (N{R}CN) or carbodiimido (NCNR) ligands, respectively.

Struktur und Schwingungsspektrum des Kaliumundecawolframats Kg6H4W11O38· 11H2O / Structure and Vibrational Spectrum of the Potassium Undecatungstate K6H4WnO38 -11 H2O

Abstract The title compound crystallizes in the triclinic space group P1̅ with lattice parameters a = 13.129 Å, b = 14.156 Å, c = 14.843 Å and α= 88.34°, β = 74.43°, γ = 70.86°. The polyanion evidently is the predominant species in pseudometatungstate phases the exact composition of which has not previously been determined.

Two New Isopolyoxotungstates(VI) with the Empirical Composition Cs2W2O7⋅2 H2O and Na2W2O7⋅H2O: An Icosatetratungstate and a Polymeric Compound

The largest isopolyoxotunstate ion known to date, W24 O8424- (structure shown in the picture), isolated as the cesium salt, and a chainlike polyoxotungstate ion made up of planar W4 O16 units, isolated as the sodium salt, hide behind the simple empirical formulas of the title compounds.

Kristallisation und Strukturuntersuchung von Alkali-Parawolframaten / Crystallization and Structure Determination of Alkaline Metal-Paratungstates

The syntheses and crystal structures of the following paratungstates-Z with different alkaline cations are reported and discussed: Na10[H2W12O42] · 20H2O (I), Na10[H2W12O42] · 27H2O (II), Na10[H2W12O47] · 28H2O (III), K10[H2W12O42] · 10H2O (IV), K6Na4[H2W12O42] · 13H2O (V), Cs6Na4[H2W12O42] · 16H2O (VI), Cs8Na2[H2W12O42] · 10H2O (VII), Cs8Na2[H2W12O42] · 12H2O (VIII), K3Na7[H2W12O42] · 24H2O (IX) and K5Na2[H2W12O42] · 12H2O (X). Priority has been set on the description of the coordination of the cations with the oxygen ligands H2W12O4210- and H2O.

Octahedro octahedra and tetrahedra. II : Tetra- to heptanuclear carbonyl(cyano)chromato, -molybdato and -tungstato complexes of 3d metals

Abstract A series of mostly homoleptic supercomplexes has been synthesized and characterized in which a central metalloid (Si IV , Ge IV , Sn IV ) or (3d) metal (Cr III , Mn II , Fe II , Co II , Ni II , Cu I , Zn II ) is surrounded by up to six ‘ligand complexes’ [NCM′(CO) 5 ] − (M′Cr o , Mo o , W o ). X-ray structures are reported for the heptanuclear six-coordinate (NEt 4 ) 2 [Si{NCCr(CO) 5 } 6 ] ( 1a ) (‘octahedro octahedron’), the hexanuclear five-coordinate (NEt 4 ) 3 [Ni{NCW(CO) 5 } 5 ] ( 8c ) and the (heteroleptic) tetranuclear four-coordinate (NEt 4 ) 2 [Co(Cl){NCCr(CO) 5 } 3 ] ( 7d ), the most striking feature being the co-existence in all complex anions of linear and distinctly bent M′ C  N  M linkages. An approximately square-pyramidal coordination sphere is established for the nickel ion in 8c . Generally, the peripheral atoms and groups (oxygen, methyl) are found in rather ill-defined positions due to their high thermal motion. In the spectrochemical series, a position slightly above N CS − (i.e. towards the stronger end) is deduced for the [NCM′(CO) 5 ] − (A) ligands from VisUV spectra. Negative FAB mass spectra reveal the presence in the matrix of the cluster anions [MA 3 ] − , [MA 4 , NEt 4 ] − ([CuA 2 ] − , [CuA 3 , Cu] − ). Thermolysis of 7a and 10a proceeds in two steps with loss of, initially, Cr(CO) 6 followed by CO and HCN as established by mass chromatography.

Homoleptische Carbenkomplexe, IV. Tetrakis(N-alkylimidazolin-2-yliden)palladium and -platin/Homoleptic Carbene Complexes, IV. Tetrakis(N-alkylimidazolin-2-ylidene)palladium and -platinum

Homoleptic complexes of palladium and platinum containing carbenoid imidazole ligands (1, 12-19 ) have been synthesized either directly from C2-lithiated N-methyl-imidazole and Pdl2 or, indirectly (and more efficiently), from isocyanides and 2-am inoacetaldehyde diethylacetale in the presence of Pdl2, Ptl2 or K2PtCl4 via the respective “ open chain” diaminocarbenes 2-11. Selected IR , NMR (1H , 13C), and pos-FAB mass spectrometric data of the new compounds are reported. The X-ray structure analysis of tetrakis(N -methylimidazolin-2-ylidene)palladium-diiodide (lb ) reveals a geometry of the heterocyclic ligands which deviates considerably from the one expected for extensive 6π-electron delocalization across the ring.

A novel triply chromium(III)-substituted Keggin anion, [A-α-SiO4W9Cr3(OH2)3O33]7-

The structure determination of K 3 H 4 [A-α-SiO 4 W 9 Cr 3 (OH 2 ) 3 O 33 ].11H 2 O, tripotassium tetrahydrogen triaquatrichromononatungstosilicate undecahydrate, represents the first X-ray analysis of a triply substituted Keggin anion containing low-valent heteroelements. The CrO 6 and WO 6 polyhedra are discussed on the basis of interatomic distances; for CrO 6 coordination an almost ideal octahedron is observed

Strukturen und Schwingungsspektren neuer Wolframatophosphate / Structures and Vibrational Spectra of Novel Tungstophosphates

Abstract A solution of Na2WO4 • 2H2O and Na2HPO4 (3:1) was acidified with acetic and perchloric acid, respectively, and yielded mixtures of crystals. These were mechanically separated under a microscope according to the appearance of the crystals and the pure phases were subjected to vibrational (IR and Ra) and X-ray investigations. The compounds have the formulae Na20P6W18O79 ·nH2O (I) with n = 41,32 and 12, and Na12P4W14O58 · 42H2O (II), respectively. By carrying out secondary reactions one obtains two more phases of (II) with less water of crystallization (36 and 34 H2O) as well as a hydrolysis product of (I), the compound Na20P5W18O75(OH)3-42H2O (III). The structures of (I) (41-hydrate), (II) (36-hydrate) and (III) were discussed. Besides centrally bound phosphate groups their anions also contain peripherally bound phosphate groups. These compounds can now be identified by the characteristic features of their vibrational spectra

Kristallstrukturen und Schwingungsspektren zweier isomerer Oktadekawolframatodiarsenate, (NH4)6As2W18O62 ·nH2O/ Crystal Structures and Vibrational Spectra of Two Isomers of Octadecatungsto-diarsenate (NH4)6As2W18O62 · nH2O

Abstract Six possible structures of As2W18O626- are discussed, and an exact nomenclature is proposed. The structures of the isomeric title compounds (I and II) were determined by X-ray diffraction. I crystallizes in space group P I with lattice parameters a = 12.965(4), b = 14.803(5), c = 18.515(6) Å; a = 96.280(23)°, β = 91.420(25)°, γ = 115.320(25)°. The anion has the configuration first observed in K6P2W18O62 · 14H2O (Dawson-structure). II was not known until now. It crystallizes in the trigonal space group R3 with lattice parameters a - b - 37.857(32). c = 13.108( 13) Å; α = β = 90°, γ = 120°. The structure of this anion differs from the Dawson-structure by the 60° rotation of both polar groups of three WO6-octahedra (β-type), followed by the 60° rotation of one of the two new AsW9O31-units. Both rotations are about the 3-fold axis. The anion is centrosymm etric. Vibrational spectra and preparation of the isomers are described.

Struktur und Eigenschaften des Kaliumhydrogendiarsenit-Hemihydrats, KHAs2O4 · 1/2 H2O / Structure and Properties of the Potassiumhydrogendiarsenite-hemihydrate, KHAs2O4 · 1/2 H2O

Abstract KHAs2O4 · 1/2 H2O crystallizes in the tetragonal space group I 4/m with the lattice constants a = 14,480 Å, c = 5,250 Å. The anion forms infinite chains, [HAs2O4]nn- , in the direction of the c axis. Arsenic is surrounded by three oxygens in trigonal pyramidal co-ordinations. Ultracentrifuge work shows that the solution contains monomeric species, probably [ASO(OH)2]-. Raman spectra gave no evidence for the existence of As-H-bonds either in the solid or in solution.