Sulfinylamid-Metathese und Nitren-Transfer an Komplexen des sechswertigen Molybdäns und Wolframs

Sulfinylamide Metathesis and Nitrene Transfer at Complexes of Hexavalent Molybdenum and Tungsten Protolysis of tungsten hexachloride with tosyl amide offers a direct access to [W(NTos)₂Cl₂]_n ( 1 a) . In presence of donor ligands coordination polymer 1 a can be converted into molecular complexes, e. g. [W(NTos)₂Cl₂(dme)] ( 1 b ), [W(NTos)₂Cl₂(PMe₃)₂] ( 1 c ) and [W(NTos)₂Cl₂(4,4′-Me₂bipy)] ( 1 d ). The synthesis of the homologous molybdenum compound [Mo(NTos)₂Cl₂]_n ( 2 a) can be achieved via metathesis of [Mo(O)₂Cl₂]_n with sulfinyl amide Tos-NSO. An attempt to synthesize a molybdenum phosphine complex in an analogous manner as 1 c , but starting from 2 a or its base adduct [Mo(NTos)₂Cl₂(dme)] ( 2 b ), leads to nitrene transfer to the phosphine. Me₃P=NTos can be detected and the d² molybdenum complex [Mo(NTos)Cl₂(PMe₃)₃] ( 3 ) is isolated. 3 is characterized by a crystal structure analysis. In phosphine complex 1 c , a similar nitrene abstraction is inhibited, in contrast 1 d is reacting with PMe₃ under nitrene abstraction to yield [W(NTos)Cl₂(4,4′-Me₂bipy)(PMe₃)₂] ( 4 ). This observation is in accord with a nitrene transfer induced via direct attack of the phosphine on the nitrogen atom of 1 d .     

Diimido‐, Imido(oxo)‐, Dioxo‐ und Imido(alkyliden)‐Halbsandwich‐Verbindungen über selektive Hydrolyse und α—H‐Abstraktion an Organylkomplexen des sechswertigen Molybdäns und Wolframs

Diimido, Imido Oxo, Dioxo, and Imido Alkylidene Halfsandwich Compounds via Selective Hydrolysis and α—H Abstraction in Molybdenum(VI) and Tungsten(VI) Organyl Complexes Organometal imides [(η⁵‐C₅R₅)M(NR′)₂Ph] (M = Mo, W, R = H, Me, R′ = Mes, tBu) 4 — 8 can be prepared by reaction of halfsandwich complexes [(η⁵‐C₅R₅)M(NR′)₂Cl] with phenyl lithium in good yields. Starting from phenyl complexes 4 — 8 as well as from previously described methyl compounds [(η⁵‐C₅Me₅)M(NtBu)₂Me] (M = Mo, W), reactions with aqueous HCl lead to imido(oxo) methyl and phenyl complexes [(η⁵‐C₅Me₅)M(NtBu)(O)(R)] M = Mo, R = Me ( 9 ), Ph ( 10 ); M = W, R = Ph ( 11 ) and dioxo complexes [(η⁵‐C₅Me₅)M(O)₂(CH₃)] M = Mo ( 12 ), M = W ( 13 ). Hydrolysis of organometal imides with conservation of M‐C σ and π bonds is in fact an attractive synthetic alternative for the synthesis of organometal oxides with respect to known strategies based on the oxidative decarbonylation of low valent alkyl CO and NO complexes. In a similar manner, protolysis of [(η⁵‐C₅H₅)W(NtBu)₂(CH₃)] and [(η⁵‐C₅Me₅)Mo(NtBu)₂(CH₃)] by HCl gas leads to [(η⁵‐C₅H₅)W(NtBu)Cl₂(CH₃)] 14 und [(η⁵‐C₅Me₅)Mo(NtBu)Cl₂(CH₃)] 15 with conservation of the M‐C bonds. The inert character of the relatively non‐polar M‐C σ bonds with respect to protolysis offers a strategy for the synthesis of methyl chloro complexes not accessible by partial methylation of [(η⁵‐C₅R₅)M(NR′)Cl₃] with MeLi. As pure substances only trimethyl compounds [(η⁵‐C₅R₅)M(NtBu)(CH₃)₃] 16 ‐ 18 , M = Mo, W, R = H, Me, are isolated. Imido(benzylidene) complexes [(η⁵‐C₅Me₅)M(NtBu)(CHPh)(CH₂Ph)] M = Mo ( 19 ), W ( 20 ) are generated by alkylation of [(η⁵‐C₅Me₅)M(NtBu)Cl₃] with PhCH₂MgCl via α‐H abstraction. Based on nmr data a trend of decreasing donor capability of the ligands [NtBu]^2— > [O]^2— > [CHR]^2— ? 2 [CH₃]^— > 2 [Cl]^— emerges.     

[MoN(NPPh3)3] – ein monomerer Nitrido-Komplex des Molybdäns

[MoN(NPPh₃)₃] – a Monomeric Nitrido Complex of Molybdenum [MoN(NPPh₃)₃] ( 1 ) has been prepared from [MoCl₃(N₃S₂)]₂ and LiNPPh₃ in toluene suspension in good yields. From n-hexane/dichloromethane solutions 1 · 2 CH₂Cl₂ crystallizes as colourless single crystals, which were suitable for a crystal structure determination. 1 forms monomeric molecules with a Mo≡N distance of 166.6 pm for the nitrido ligand, which corresponds to a triple bond, and MoN-bonds of 193.6 pm on average of the NPPh₃^–-ligands, corresponding to shortened single bonds.     

Neue Phosphaniminato‐Komplexe von Molybdän und Wolfram. Die Kristallstrukturen von [(μ‐S2N2){MoCl4(NPPh3)}2], [Mo(NPPh3)4][BF4]2, [W(S)2(NPPh3)2] und [Ph3PNH2]+[SCN]–

New Phosphoraneiminato Complexes of Molybdenum and Tungsten. Crystal Structures of [(μ‐S₂N₂){MoCl₄(NPPh₃)}₂], [Mo(NPPh₃)₄][BF₄]₂, [W(S)₂(NPPh₃)₂], and [Ph₃PNH₂]⁺[SCN]^– The binuclear molybdenum(V)phosphoraneiminato complex [(μ‐S₂N₂){Mo^VCl₄(NPPh₃)}₂] ( 1 ) has been prepared by the reaction of the chlorothionitreno complex [Mo^VICl₄(NSCl)]₂ with Me₃SiNPPh₃ in dichloromethane forming green crystals. The temperature dependent magnetic susceptibility in the range of 2–30 K shows ideal behaviour according to the Curie law with a magnetic moment of 1.60 B.M. According to the crystal structure determination 1 forms centrosymmetric molecules in which the molybdenum atoms are connected by the nitrogen atoms of the S₂N₂ molecule. In trans‐position to it the nitrogen atoms of the phosphoraneiminato groups (NPPh₃^–) are coordinated with Mo–N bond lengths of 171(1) pm. The tetrakis(phosphoraneiminato) complex [Mo(NPPh₃)₄]‐ [BF₄]₂ ( 2 ) has been obtained as colourless crystal needles by the reaction of MoN(NPPh₃)₃ with boron trifluoride etherate in toluene solution. In the dication the molybdenum atom is tetrahedrally coordinated by the nitrogen atoms of the (NPPh₃^–) groups with Mo–N bond lengths of 179,8–181,0(3) pm. The dithio‐bis(phosphoraneiminato) tungsten complex [W(S)₂(NPPh₃)₂] ( 3 ) is formed as yellow crystals as well as [Ph₃PNH₂]⁺[SCN]^– ( 4 ) from the reaction of WN(NPPh₃)₃ with carbon disulfide in tetrahydrofurane in the presence of traces of water. 3 has a monomeric molecular structure with tetrahedrally coordinated tungsten atom with bond lengths W–S of 214.5(5) pm and W–N of 179(1) pm. In the structure of 4 the thiocyanate ions are associated by hydrogen bonds of the NH₂ group of the [Ph₃PNH₂]⁺ ion to give a zigzag chain. 1 : Space group Pbca, Z = 4, lattice constants at –80 °C: a = 1647.9(3), b = 1460.8(2), c = 1810.4(4) pm; R₁ = 0.0981. 2 : Space group P1, Z = 2, lattice constants at –80 °C: a = 1162.5(1), b = 1238.0(1), c = 2346.2(2) pm; α = 103.14(1)°, β = 90.13(1)°, γ = 97.66(1)°; R₁ = 0.0423. 3 : Space group Fdd2, Z = 8, lattice constants at –80 °C: a = 3310.1(4), b = 2059.7(2), c = 966,7(1) pm; R₁ = 0.0696. 4 : Space group P2₁2₁2₁, Z = 4, lattice constants at –80 °C: a = 1118.4(1), b = 1206.7(1), c = 1279.9(1) pm; R₁ = 0.0311.     

Kristallstruktur des Molybdän(V)‐Imido‐Komplexes [MoCl3(NtBu)(H2NtBu)]2 · 1/2 C7H8

Crystal Structure of the Molybdenum(V) Complex [MoCl₃(N^tBu)(H₂N^tBu)]₂ · ¹/₂ C₇H₈ Green moisture sensitive single crystals of [MoCl₃(N^tBu)(H₂N^tBu)]₂ ( 1 · ¹/₂ C₇H₈) have been prepared from molybdenum pentachloride with Me₂Si(HN^tBu)₂ in toluene solution; they were suitable for a crystal structure determination. 1 · ¹/₂ C₇H₈: Space group P 1, Z = 2, lattice dimensions at –83 °C: a = 696.9(1), b = 1470.9(2), c = 1579.0(2) pm, α = 96.673(13)°, β = 92.014(14)°, γ = 94.852(14)°, R = 0.0321. 1 forms centrosymmetric molecules in which the molybdenum atoms are linked by two μ‐Cl‐bridges with MoCl bond lengths of 245.7 and 270.2 pm in average of the two crystallographically independent individuals. The longer MoCl bond is in trans‐position to the nitrogen atom of the imido ligand (MoN distance 169.0 pm, MoNC bond angle 167.0° in average).     

Zweikern-Komplexe des Wolframs und Molybdäns mit zentraler {XMS2 MX}2+-Einheit (X=O,S) und S 2 2− -bzw. S 4 2− -Liganden

The synthesis and crystal structures of the compounds [PPh ₄]₂[W₂S₁₂]·0.5DMF, [PPh ₄]₂[W₂O₂S₁₀]·0.5DMF, [PPh ₄]₂[W₂S₁₀]··0.5DMF, [PPh ₄][NEt ₄][Mo₂OS₇]·CH₃CN, and [PPh ₄]₂[Mo₂O₂S₁₀] are reported.

     

Synthese,Struktur und Reaktivität von Tris‐, Bis‐ und Mono(2,4‐dimethylpentadienyl)‐Komplexen des Neodyms,Lanthans und des Yttriums

The tris(2,4‐dimethylpentadienyl) complexes [Ln(η⁵‐Me₂C₅H₅)₃] (Ln = Nd, La, Y) are obtained analytically pure by reaction of the tribromides LnBr₃·nTHF with the potassium compound K(Me₂C₅H₅)(thf)_n in THF in good yields. The structural characterization is carried out by X‐ray crystal structure analysis and NMR‐spectroscopically. The tris complexes can be transformed into the dimeric bis(2,4‐dimethylpentadienyl) complexes [Ln₂(η⁵‐Me₂C₅H₅)₄X₂] (Ln, X: Nd, Cl, Br, I; La, Br, I; Y, Br) by reaction with the trihalides THF solvates in the molar ratio 2:1 in toluene. Structure and bonding conditions are determined for selected compounds by X‐ray crystal structure analysis and NMR‐spectroscopically in general. The dimer‐monomer equilibrium existing in solution was investigated NMR‐spectroscopically in dependence of the donor strength of the solvent and could be established also by preparation of the corresponding monomer neutral ligand complexes [Ln(η⁵‐Me₂C₅H₅)₂X(L)] (Ln, X, L: Nd, Br, py; La, Cl, thf; Br, py; Y, Br, thf). Finally the possibilities for preparation of mono(2,4‐dimethylpentadienyl)lanthanoid(III)‐dibromid complexes are shown and the hexameric structure of the lanthanum complex [La₆(η⁵‐Me₂C₅H₅)₆Br₁₂(thf)₄] is proved by X‐ray crystal structure analysis.     

Oxo-Phosphaniminato-Komplexe von Molybdän und Wolfram. Die Kristallstrukturen von [Mo(O)2(NPPh3)2] und [WO(NPPh3)3]2[W6O19]

Oxo-phosphoraneiminato Complexes of Molybdenum and Tungsten. Crystal Structures of [Mo(O)₂(NPPh₃)₂] and [WO(NPPh₃)₃]₂[W₆O₁₉] The dioxo-phosphoraneiminato complexes [Mo(O)₂(NPPh₃)₂] ( 1 ) and [W(O)₂(NPPh₃)₂] ( 2 ) originate from hydrolysis of the nitrido complexes [MN(NPPh₃)₃] (M = Mo, W). They form colourless crystals, which are characterized by IR and NMR spectroscopy as well as by mass spectrometry. According to the crystal structure analysis of 1 (space group Fdd2, Z = 8; lattice dimensions at –83 °C: a = 1953.3(1), b = 3275.8(3), c = 953.4(1) pm) there are monomeric molecules with tetrahedrally coordinated molybdenum atoms. The distances MoO of 171.2 pm and MoN of 185.9 pm correspond to double bonds. In dichloromethane solution 2 undergoes further hydrolysis with colourless crystals of [WO(NPPh₃)₃]₂[W₆O₁₉] ( 3 ) originating, which are characterized crystallographically (space group Pbcn, Z = 4; lattice dimensions at –50 °C: a = 3225.1(6), b = 1803.6(3), c = 1811.9(3) pm). 3 consists of cations [WO(NPPh₃)₃]⁺ with tetrahedrally coordinated tungsten atoms and of the known [W₆O₁₉]^2– anions. The tungsten atoms of the cations show distances WO of 171.8 pm and WN of 182 pm which correspond to double bonds as in 1 .     

Molybdän‐ und Wolfram‐Komplexe mit MNS‐Sequenzen. Die Kristallstrukturen von [MoCl3(N3S2)(1,4‐Dioxan)2] und [Mo2Cl2(μ‐NSN)2(μ‐O)(NCMe3)(OCMe3)2]2

Molybdenum and Tungsten Complexes with MNS Sequences. Crystal Structures of [MoCl₃(N₃S₂)(1,4‐dioxane)₂] and [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ The cyclo‐thiazeno complexes [Cl₃MNSNSN]₂ of molybdenum and tungsten react with 1,4‐dioxane in dichloromethane suspension to give the binuclear donor‐acceptor complexes [μ‐(1,4‐dioxane){MCl₃(N₃S₂)}₂] which are characterized by IR spectroscopy. With excess 1,4‐dioxane the molybdenum compound forms the complex [MoCl₃(N₃S₂)(1,4‐dioxane)₂] in which, according to the crystal structure determination, one of the dioxane molecules coordinates at the molybdenum atom, the other one at one of the sulfur atoms of the cyclo‐thiazeno ring. The μ‐(NSN^2–) complex [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ has been obtained by the reaction of [MoN(OCMe₃)₃] with trithiazyle chloride in carbontetrachloride solution. According to the crystal structure determination this compound forms centrosymmetric dimeric molecules via two of the nitrogen atoms of two of the μ‐(NSN) groups to give a Mo₂N₂ fourmembered ring. [MoCl₃(N₃S₂)(1,4‐dioxane)₂]: Space group P2₁/c, Z = 4, lattice dimensions at –70 °C: a = 1522.9(2); b = 990.3(1); c = 1161.7(1) pm; β = 106.31(1)°, R₁ = 0.0317. [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ · 4 CCl₄: Space group P2₁/c, Z = 2, lattice dimensions at –83 °C: a = 1216.7(1); b = 2193.1(2); c = 1321.8(1) pm; β = 98.23(1)°; R₁ = 0.0507.     

Sterisch abgeschirmte Nitridokomplexe von Molybdän und Wolfram Die Kristallstrukturen von [MoN(NPh2)3] und [W4N4(NPh2)6(OnC4H9)2]

Stericly Shielded Nitrido Complexes of Molybdenum and Tungsten. The Crystal Structures of [MoN(NPh₂)₃] and [W₄N₄(NPh₂)₆(OⁿC₄H₉)₂] The reactions of MoNCl₃ and WNCl₃, respectively, with lithium diphenylamide in tetrahydrofurane produce the monomeric nitrido complexes MN(NPh₂)₃ with CN = 4 at the metal atoms. In the presence of lithium-n-butyl LiNPh₂ and WNCl₃ also form the tetrameric nitrido complex [W₄N₄(NPh₂)₆(OⁿC₄H₉)₂] which contains W^V and W^VI. The compounds are characterized by their i.r. spectra, by X-ray structural analysis, and, partially, by ¹H and ¹³C n.m.r. spectroscopy. MoN(NPh₂)₃: Space group P1 , Z = 2, 4060 observed independent reflexions, R = 0.031. Lattice dimensions at 20°C: a = 956.2(4) pm, b = 1 015.9(2) pm, c = 1 598.1(3) pm; α = 79.06(2)°, β = 85.67(3)°, γ = 82.57(3)°. The compound forms monomeric molecules with Mo?N bond lengths of 163.4 pm and mean Mo? NPh₂ distances of 199.2 pm. [W₄N₄(NPh₂)₆(OⁿC₄H₉)₂]: Space group P2₁/n, Z = 2, 1903 observed independent reflexions, R=0.039. Lattice parameters at 19°C: a = 1582.2(3) pm, b = 1182.4(2) pm, c = 2053.3(4) pm; β = 103.77(2)°. The compound forms centrosymmetric molecules, in which the central W–W dumb-bell (bond length 253.5 pm) is linked by the nitrido ligands of two WN₂(NPh₂)₂=units in a T shaped order of the N-atoms.     

Synthese und Kristallstruktur der Molybdännitrido‐Komplexe [MoNCl3(MeCN)]4 und [MoNCl2(bipy)]4

Syntheses and Crystal Structures of the Nitrido Complexes [MoNCl₃(MeCN)]₄ and [MoNCl₂(bipy)]₄ [MoNCl₃(MeCN)]₄ ( 1 ) is obtained by the reaction of MoCl₄(MeCN)₂ with Me₃SiN₃ in CH₂Cl₂ as a sparingly soluble and water sensitive red compound. It crystallizes as 1 · 3 CH₂Cl₂ in the triclinic space group P 1 with a = 889.7(1), b = 1004.8(1), c = 1270.4(2) pm; α = 71.69(1)°; β = 73.63(1)°; γ = 86.32(1)°, and Z = 1. It forms centrosymmetric tetranuclear complexes, in which the Mo atoms are connected by asymmetric and linear nitrido bridges with distances Mo–N of 167.5 and 214.3 pm. The acetonitrile molecules are coordinated with a long bond length Mo–N of 241 pm in trans position to the Mo–N triple bond. The reaction of 1 with 2,2′‐bipyridine in CH₂Cl₂/THF yields the tetranuclear molybdenum(V) complex [MoNCl₂(bipy)]₄ ( 2 ) as main product. It crystallizes in the tetragonal space group P4₂/n with a = 1637.5(2), c = 1018.3(2) pm, and Z = 2. In the tetranuclear complexes with the symmetry S₄ linear and asymmetric nitrido bridges connect the Mo atoms to form an almost planar eight membered Mo–N ring with distances Mo–N of 173 and 203 pm. The bipyridine molecules coordinate as chelates in cis and trans position to the Mo–N triple bond. In this case the trans influence causes different Mo–N distances of 219 and 232 pm.     

Penicillamin-Komplexe des Nickels,Chroms und Molybdäns — Strukturelle Besonderheiten und biologische/medizinische Relevanz

Penicillamine Complexes of Nickel, Chromium, and Molybdenum — Structural Particularity and Biological/Medical Relevance The compounds Tl₂[Ni^II(H₂O)₆][Ni^II(D-pen)(L-pen)]₂[Ni^II(SCN)₂(H₂O)₄] 1 , Tl[Ni^II(D-pen)₂H] · H₂O 2 , Tl[Cr^III(D-pen)₂] 3 , and Na₂[MoO₄(pen)₂] · 3 CH₃OH · 3 H₂O 4 have been prepared by the reaction of nickel nitrate (for 1 ), nickel acetate (for 2 ), potassium chromate (for 3 ), and sodium molybdate (for 4 ) with D- and D, L-penicillamine, respectively. They were characterized by single-crystal X-ray structure analysis and other physical methods. Whereas penicillamine acts as a bidentate (N, S)-ligand in 1 and 2 , Cr^III (in 3 ), and Mo^V (in 4 ) are coordinated to the three ligand atoms N, O, and S. The presence of three different types of Ni^II-complexes a cationic, a neutral, and an anionic one in 1 is remarkable. For crystal data see Inhaltsübersicht.     

Darstellung,Schwingungsspektrum und Kristallstruktur von (n‐Bu4N)2[(W6Cl)F] · 2 CH2Cl2 und 19F‐NMR‐spektroskopischer Nachweis der gemischten Clusteranionen [(W6Cl)FCl]2–, n = 1–6

Synthesis, Vibrational Spectra, and Crystal Structure of ( n ‐Bu₄N)₂[(W₆Cl )F ] · 2 CH₂Cl₂ and ¹⁹F NMR Spectroscopic Evidence of the Mixed Cluster Anions [(W₆Cl )F Cl ]^2–, n = 1–6 The reaction of (n‐Bu₄N)₂[(W₆Cl)Cl] with CF₃COOH in dichloromethane gives intermediately a mixture of the cluster anions [(W₆Cl)(CF₃COO)Cl]^2–, n = 1–6. By treatment with NH₄F the outer sphere coordinated trifluoracetato ligands are easily substituted and the components of the series [(W₆Cl)FCl], n = 1–6 are formed and characterized by their distinct ¹⁹F NMR chemical shifts. An X‐ray structure determination has been performed on a single crystal of (n‐Bu₄N)₂[(W₆Cl)F] · 2 CH₂Cl₂ (orthorhombic, space group Pbca, a = 15.628(4), b = 17.656(3), c = 20.687(4) Å, Z = 4). The low temperatur IR (60 K) and Raman (20 K) spectra are assigned by normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constants are f_d(WW) = 1.89, f_d(WF) = 2.43 and f_d(WCl) = 0.93 mdyn/Å.     

(Carb)2SnF4 (Carb = 2, 3‐Dihydro‐1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐yliden – ein Carbenkomplex des vierwertigen Zinns

2, 3‐Dihydro‐1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐ylidene ( 1 , Carb) reacts with tin tetrafluoride to give the complex (Carb)₂SnF₄ ( 3 ). The ligand properties of 1 are discussed in terms of the crystal structure and NMR data of 3 .     

Heterobimetallic Complexes: Substitution Effects in the [Tetracarbonylrhodiumbis{μ‐(diphenylphosphino)}{μ‐(η:η2‐(4‐diphenylphosphino‐κP)‐2‐methyl‐oxobutyl)}molybdenum](Mo‐Rh) System

Syntheses of the array of heterobimetallic complexes [(OC)₃M(μ‐PPh₂)₂(μ‐O‐C(CHMe(CH₂)₂PPh₂)RhL], M = Cr, Mo, W, L = ^tBuNC, are described, extending the previous study of the counterpart array for L = CO. A single crystal X‐ray structure determination is reported for the M = Mo adduct, enabling comparison with its previously reported L = CO counterpart, for which an improved redetermination is also reported. In the present complex the ^tBuNC ligand is found to be much more weakly bound (Rh‐C 2.026(5) Å) than the carbonyl group it displaces (Rh‐C 1.945(2) Å) with concomitant minor impact on the remainder of the rhodium ambience.     

Bildung und Struktur von [μ‐(1,2 : 2‐η‐tBu2P–P){Mo(CO)2cp′}2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXIV. Formation and Structure of [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂] [cp′Mo(CO)₂]₂ (cp′ = C₅H₄^tBu) reacts with ^tBu₂P–P=P(Me)^tBu₂ to yield the compound [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂], which crystallizes in the space group P2₁2₁2₁ with a = 1202.42(7), b = 1552.48(8), and c = 1765.3(1) pm.     

Synthese und Kristallstrukturanalyse von NaSrMg2F7, einer vollständig fluorierten Verbindung des Pyrochlortyps

Synthesis and Crystal Structure Analysis of NaSrMg₂F₇, a Fully Fluorinated Compound of the Pyrochlore Family During our research on alkali‐fluorides, the compound NaSrMg₂F₇ has been prepared by a precipitation reaction of Sr²⁺, Mg²⁺ and Na⁺ with F^– for the first time. The powder crystallizes as a single phase in the form of spherical agglomerates ∼0.25 μm in diameter. The compound crystallizes in the space group Fd 3 m (Nr. 227) with lattice parameter a = 10.4379(4) Å. Structural analysis by the Rietveld method was done from X‐ray diffraction data. In agreement with the structure analysis, spectroscopical investigations confirm the presence of two coupled fluoride ions. The crystal structure corresponds to the pyrochlore structure type A₂B₂X₇ with 50% occupation of Sr²⁺ or Na⁺ at the A site.     

Halogeno-Nitrosylkomplexe von Molybdän und Wolfram. Die Kristallstrukturen von [Na2(15-Krone-5)2(CH3CN)][MoCl4(NO)2] und [Na(15-Krone-5)]2[MoF4Cl(NO)]

Halogeno-Nitrosyl Complexes of Molybdenum and Tungsten. Crystal Structures of [Na₂(15-Crown-5)₂(CH₃CN)][MoCl₄(NO)₂] and [Na(15-Crown-5)]₂[MoF₄Cl(NO)] MoCl₂(NO)₂ and WCl₂(NO)₂, respectively, react with excess sodium fluoride in acetonitrile at room temperature and in the presence of 15-crown-5 to give crystalline mixtures, which consist of the title compounds, respectively of [Na(15-crown-5)]₂[WCl₄(NO)₂] and [Na(15-crown-5)]₂[WF₄Cl(NO)], and which can be separated by selection. The complexes are characterized by their i.r. spectra, the molybdenum compounds additionally by crystal structure determinations. [Na₂(15-crown-5)₂(CH₃CN)][MoCl₄(NO)₂]: Space group P2₁, Z = 2, 5415 independent unique reflexions, R = 0.039. Lattice dimensions at ?10°C: a = 984.3, b = 1231.1, c = 1483.0 pm, β = 105.67°. The compound consists of cations [Ne(l5-crown-5)(CH₃CN)]⁺, in which the sodium ion is surrounded by the five O-atoms of the crown ether and by the N-atom of the acetonitrile molecule, as well as of anions, which form an ion pair {Na(15-crown-5)[MoCl₄(NO)₂]}^?. In the in pairs the sodium ion is coordinated by the five oxygen atoms of the crown ether and by two chlorine atoms of the [MoCI₄(NO)₂]^2? unit. The nitrosyl ligands take the cis-position a t the molybdenum atom which is in a distorted octahedrally fashion. [Na(15-crown-5)]₂[MoF₄Cl(NO)]. Space group C2/c, Z = 4, 1933 independent unique reflexions, R = 0.078. Lattice dimensions at ?7O°C: D : 1.585.8, b = 1171.5, c = 1771.5 pm, β = 114.91°. The compound forms an ion triple, in which the sodium ions are linked to five oxygen atoms each of the crown ether molecules, and to two F-atoms of the [MoF₄Cl(NO)]^2? unit. The F-atom which is arranged in trans-position to the nitrosyl ligand coordinates with both sodium ions; thus an unusual T-shaped arrangement results for this F-atom. The sole terminal F-Atom and the Cl-atom are disordered in two positions.     

Synthesis and Structures of the Ligands 1‐Methylimidazol‐2‐yl(pyridin‐2‐yl)methanone {(py)(mim)CO} and 1‐Benzylimidazol‐2‐yl(1‐phenylaldimine) (PhN=CHbim) as their Tetracarbonylmolybdenum(0) Complexes [Mo(CO)4(L2‐N,N′)]

The complexes [Mo(CO)₄(L₂‐N,N′)] [L₂ = 1‐methylimidazol‐2‐yl(pyridin‐2‐yl)methanone and 1‐benzylimidazol‐2‐yl(1‐phenylaldimine)] have been synthesized from hexacarbonylmolybdenum(0) in order to define the coordination characteristics of the bidentate nitrogen‐donor ligands; the complexes exhibit distorted octahedral coordination for molybdenum(0) and cis‐bidentate ligand configurations.     

Sr2(OLi2Sr4)[CrN4]2, ein Nitridochromat(VI)‐Oxid mit Sauerstoff in tetragonal‐bipyramidaler Koordination durch Lithium und Strontium

Sr₂(OLi₂Sr₄)[CrN₄]₂, a Nitridochromate(VI)‐Oxide with Oxygen in Tetragonal‐Bipyramidal Coordination by Lithium and Strontium Green gleaming crystals of Sr₂(OLi₂Sr₄)[CrN₄]₂ were prepared by reaction of Li, Sr and CrN/Cr₂N (approximate 1 : 1 mixture) with flowing nitrogen at 900 °C (molar overall composition Li : Sr : Cr = 6 : 1 : ∼3). The oxygen content results from a leak in the gas supply. The crystal structure was determined by single crystal methods (triclinic; P1; a = 615.87(9) pm, b = 682.50(10) pm, c = 754.30(8) pm, α = 82.302(14)°, β = 75.197(10)°, γ = 70.133(13)°; Z = 1) and contains distorted tetragonal bipyramids (OLi₂Sr₄)⁸⁺ and [Cr^VIN₄]^6–‐tetrahedra besides Sr²⁺.