Chloro Bridges Research Articles

Synthese und Kristallstruktur des Imidokomplexes {TaCl4NC(Ph)[N(SiMe3)2]}2 · 2 CH2Cl2 / Synthesis and Crystal Structure of the Imido Complex {TaCl4NC(Ph)[N(SiMe3)2]}2 · 2 CH2Cl2

The title compound has been prepared by the reaction of N,N,N′-tris(trimethylsilyl)benzamidine with tantalum pentachloride in CH2Cl2 suspension, forming amber-coloured, moisturesensitive crystals, which were characterized by an X-ray structure determination. Space group P 21/n, Z = 2, 4895 observed independent reflexions, R = 0.059. Lattice dimensions (-65°C): a = 1165.2(6), b = 1335.4(6), c = 1629.0(7) pm, β = 93.23(4)°. The complex forms centrosymmetric molecules dimerized via chloro bridges TaCl2Ta with TaCl bond lengths of 247.2(2) and 277.1(2) pm, the longer one being in trans-position to the imido group, which can be formulated as [xxx] (bond lengths Ta=Ν = 183.5(8), C=N = 134(1) pm, bond angle TaNC = 162.7(7)°).

Komplexkatalyse: XXXI. Kristallstruktur des hexameren Mono-2,4-dimethyl-pentadienyldichlorenoedymiun(III)·0.33Tetrahydrofuran. [Nd 6(2,4-C 7H 11) 6Cl 12(THF) 2] eines Präkatalysators für die 1,4- cis-Polymerisation des Butadiens

Nd(2,4-C 7H 11)Cl 2 · 0.33THF was synthesized by reactin of Nd(2,4-C 7H 11) 3 with NdCl 3 · 2THF. The crystal structure study confirms the exitence of a hexameric unit Nd 6Cl 12(2,4-C 7H 11) 6 · 2THF which consists of two Nd 3Cl 5 entities connected via two chloro bridges. The structure of the Nd 3Cl 5 entity contains an unusual polyhedron, namely a distorted hexagonal bipyramid. The 2,4-C 7H 11 anion is connected tot he neodymium atoms in a pentahapto mode of bonding.

Notizen: Synthese und IR-Spektrum von [MoCl4(NCl)]2 / Synthesis and IR Spectrum of [MoC14(NCl)]2

[MoCl4(NCl)]2 has been prepared by the reaction o f molybdenum hexacarbonyl with excess nitrogen trichloride in CCl4 solution; the product is a red, moisture-sensitive crystal powder. Decomposition above 100 °C leads to MoNCl3. According to the IR spectrum, [MoCl4(NCl)]2 is dimerized via chloro bridges, the group being linear.

Molybdännitridtrichlorid-2,3,3-trichloracrylnitril, [MoNCI3 · NC-C2Cl3]2 Synthese, IR-Spektrum und Kristallstruktur / Molybdenumnitridetrichloride-2,3,3-trichloroacrylnitrile, [MoNCl3 · NC—C2Cl3]2 Synthesis, IR Spectrum, and Crystal Structure

Abstract [MONCl3 · NC - C2Cl3]2 has been prepared by the reaction of MONCl3 with trichloromethyl isocyanidedichloride, CCl3NCCl2 , in CH2Cl2 suspension. The compound forms redbrown. mois-ture sensitive crystals, which were characterized by their IR spectrum as well as by a crystal structure determination (2482 independent observed reflexions, R = 0.048). Crystal data (-70 °C): Space group P21/c, Z = 2, a = 674.2(2); b = 2128.2(11); c = 786.0(4) pm: β = 102.81(3)°. [MONCl3 • NC-C2Cl3]2 forms centrosymmetric dimeric molecules via chloro bridges with Mo-Cl bond lengths of 240.7 and 276.0 pm. The longer MoCl bond of the MOCl2MO ring is caused by the trans influence of the nitride ligand; the MoN bond length of 167 pm corresponds with a triple bond. The 2,3,3-trichloroacrylnitrile ligand is bonded by its nitrogen atom with a bond length of Mo -N = 216 pm; the Mo-N≡C-C sequence is almost linear with a remarkable short C-C bond of 143.0 pm.

N,N'-Bis(trimethylsilyl)benzamidinato-Koniplexe von Titan und Zirkon. Die Kristallstrukturen von [C6H5-C(NSiMe3)2MCl3]2; M = Ti, Zr / N,N'-Bis(trimethylsilyl)benzamidinato Complexes of Titanium and Zirconium. The Crystal Structures of [C6H5-C(NSiMe3)2MCl3 ]2 ; M = Ti, Zr

Abstract The N,N'-bis(trimethylsilyl)benzamidinato complexes [C6H5 -C(NSiMe3)2MCl3]2(M = Ti. Zr) have been prepared by the reactions of N,N,N'-tris(trimethylsilyl)benzamidine [C6H5-C(NSiMe3)N(SiMe3)2] with titanium tetrachloride, and zirconium tetrachloride, respec-tively. The compounds form moisture sensitive, dark red (Ti) and white (Zr) crystals, which were characterized by crystal structure determinations. [C6H5-C(NSiMe3)2TiCl3]2 : space group P21/rc. Z = 2, 4373 observed independent reflexions, R = 0.034. Lattice dimensions (-90 °C): a - 959.0(8); b = 1196.5(8); c = 1770.9(11) pm; β = 93.79(4)°. [C6H5-C(NSiMe3)2ZrCl3]2 : space group P21/n. Z = 2, 3160 observed independent reflexions, R = 0.031. Lattice dimensions (-90 °C): a = 971.6(7); b = 1222.2(9); c = 1792.9(10) pm; β = 93.51(5)°. Both complexes crystallize isotypically, forming centrosymmetric dimeric molecules via chloro bridges with bond lengths of 242.0 and 253.8 pm (Ti), and of 253.7 and 264.9 pm (Zr). The metal atoms complete their distorted octahedral surroundings with two chlorine ligands and the nitrogen atoms of the chelating amidinato ligand. The N atoms of the amidinato group are in equatorial and axial positions. This accounts for the different metal-nitrogen bond lengths of 207 pm (ax) and 199 pm (eq) in the titanium compound and 219 pm (ax) and 214 pm (eq) in the zirconium complex.

Reaktionen von Titantetrachlorid mit Bistrimethylsilylsulfid. Die Kristallstrukturen von (NEt4)2[TiSCl4], (PPh4)2[TiSCl4]·2CH2Cl2, (PPh4)2[Ti3O(S2)3Cl6]CH3CN und Ti4O(S2)4Cl6 / Reactions of Titanium Tetrachloride with Bistrimethylsilyl Sulfide. Crystal Structures of (NEt4)2[TiSCl4], (PPh4)2[TiSCl4]·2CH2Cl2, (PPh4)2[Ti3O(S2)3Cl6]CH3CN and Ti4O(S2)4Cl6

The reaction of TiCl4 with (Me3Si)2S in dichloromethane yields black, insoluble, impure TiSCl2. In the presence of oxygen, additionally Ti3O(S2)3Cl4 and Ti4O(S2)4Cl6 are formed. By reactions of TiSCl2 with NEt4Cl and PPh4Cl in dichloromethane (NEt4)2[TiSCl2] and (PPh4)2[TiSCl4] ·2CH2Cl2 are formed, respectively. They were characterized by their IR spectra and by X-ray crystal structure determinations. They contain the square-pyramidal [TiSCl4]2- ion. which has a rather short Ti = S bond of 211.1(2) pm. Crystal data: (NEt4)2[TiSCl4]: tetragonal. P4/n, a = 923.9(3). c = 1406.7(2) pm. Z = 2. 966 unique observed reflexions. R = 0.053; positionally disordered ethyl groups. (PPh4)2[TiSCl4] · 2CH2Cl2: triclinic, P1, a = 1009.7(4), b = 1115.1(3). c = 1242.1(5) pm, α = 70.27(3), β = 79.06(3), γ = 81.37(3)°, Z = 1, 1504 reflexions, β-(AsPh4)2UCl6·2CH2Cl2 structure type, high R = 0.107 due to positional disorder of the anion. Addition of NEt4Cl or PPh4Cl in CH2Cl2 to the primary reaction product in presence of O2 yields (NEt4)2[Ti3O(S2)3Cl6] and (PPh4)2[Ti,O(S2)3Cl6] · CH2Cl2, respectively. Upon recrystallization of the latter from acetonitrile, (PPh4)2[Ti3O(S2)3Cl6] · CH3CN is obtained which forms triclinic crystals with a = 1138.8(3). b = 1268.8(4), c = 2166.4(6) pm, α = 101.26(3). β = 97.21(2). γ = 109.24(2)°, Z = 2, P1 (3053 reflexions, R = 0.070). The [Ti3O(S2)3Cl6]2- ion has a cluster-like structure with Ti atoms at the vertices of a triangle, with a μ3-O bridging atom and with tree bridging disulfide groups. Crystal data for Ti4O(S2)4Cl6: monoclinic, C2/c, a - 917.3(2), b - 1632.5(2), c = 1268.5(2) pm, β - 108.35(2)°, Z = 4. 1009 reflexions. R = 0.027. In the Ti4O(S2)4Cl6 molecule, four Ti atoms form a distorted tetrahedron around an μ4-O atom; two edges of the tetrahedron are spanned by chloro bridges, four edges by disulfide bridges.

Chrom(III)- und Chrom(IV)-Komplexe der π-Aromaten-Reihe: Präparative und strukturchemische Aspekte

The dinuclear, paramagnetic organochromium(III) complex [(η 5-C 5Me 5)Cr(μ-Cl)CH 3] 2 ( 2) containing bridging chloro and terminal methyl ligands (X-ray diffraction study) can be obtained from thf-solvated methylchromium dichloride ( 1a) or from chromium trichloride ( 1b) with common transfer reagents of the C 5Me 5-group in 40 and 65% yield, respectively, thus constituting a convenient starting material in organochromium chemistry of intermediate metal oxidation states. Treatment of 2 with trimethylphosphane effects cleavage of the chloro-bridged structure to give the mononuclear complex (η 5-C 5Me 5)CrCl(CH 3)(PMe 3) ( 3), whereas reaction with sodium phenoxide involves substitution of the bridge ligand with formation of [(η 5-C 5Me 5)Cr(μ-OC 6H 5)CH 3] 2 ( 4). Oxidation of 2 with bromine gives (chiral) (η 5-C 5Me 5)CrCl(Br)(CH 3) ( 5) selectively as a pair of enantiomers, which can then be converted into the diamagnetic Cr IV alkoxide complex (η 5-C 5Me 5)Cr(CH 3-(OC 6H 5) 2 ( 6). By contrast, no chromium oxidation occurs when 2 is treated with iodine; rather the mixed chloroiodo derivative of net composition [(η 5-C 5Me 5)Cr-Cl 1/2I 3/2] 2·I 2 ( 7) is formed, and is a polymer with bridging iodine (I 2) in the crystal.

ChemInform Abstract: N‐Chloro‐Nitrene Complexes of Tungsten: WCl4(NCl) and (CH3CN‐WCl4(NCl)).

AbstractThe IR spectrum of the title compound (III) indicates the formation of dimeric units via chloro bridges.

N-Chlornitrenokomplexe des Wolframs: WCl4 (NCl) und [CH3CN-WCl4 (NCl)] / N-Chloro-Nitrene Complexes of Tungsten:WCl4 (NCl) and [CH3CN-WCl4 (NCl)

WCl4(NCl) has been prepared as a red-brown crystal powder by the reaction of tungsten hexacarbonyl with excess nitrogen trichloride in boiling CCl4. The complex is associated via chloro bridges, forming dimeric units, according to the IR spectrum. Thermal decomposition at 200 °C leads to tungsten nitride trichloride, WNCl3,. With acetonitrile, WCl4(NCl) reacts with formation of the monomeric complex [CH,CN-WCl4(NCl)], which was characterized by its IR spectrum as well as by an X-ray structure determination. Crystal data: space group P21/m, Z = 2 (1387 independent observed reflexions, R = 0.07). Lattice dimensions at 20 °C: a = 590.4(3), b = 729.0(3), c = 1124.6(4) pm, β = 100.63(2)°. The complex forms monomeric molecules, in which the tungsten atom has a distorted octahedral environment of four chlorine atoms in equatorial positions, and the acetonitrile molecule in trans-position to the group. Bond lengths WN = 172 and NCI = 161 pm; bond angle WNCl = 175.5°.

Unsymmetrisch substituierte Alkinkomplexe von Wolfram(IV). Die Kristallstruktur von PPh 4[WCl 5(HCCPh)]·CH 2Cl 2

The alkynes Me 3SiCCH and PhCCH react with tungsten hexachloride in CCl 4 and CH 2Cl 2, respectively, to form the alkyne complexes [WCl 4(Me 3SiCCH)] 2 ( 1) and [WCl 4(PhCCH)] 2 ( 2). Their IR spectra indicate that they are dimerised via chloro bridges. Complexes 1 and 2 are soluble in dichloromethane, when donor solvents like diethyl either or acetonitrile are added. The 1H and 13C NMR spectra of the ether adduct of 2 are consistent with alkyne ligand-like bonding which is best described as one of the metallocyclopropene type. Reaction of 2 with tetraphenyl-phosphonium chloride in CH 2Cl 2 forms the complex PPh 4[WCl 5(PhCCH)]·CH 2Cl 2 ( 3), which is soluble in CH 2Cl 2. Its structure was determined from X-ray diffraction studies: Space group P2 1 c , Z = 4, R = 0.072 for 5769 observed, independent reflections. The lattice constants at 90 K are: α 751.3, b 1620.9, c 2752.6 pm; β 94.47°. The crystal lattice of compound 3 consists of PPh 4 + and [WCl 5(PhCCH)] - ions, and includes CH 2Cl 2 molecules. In the anion the alkyne ligand is coordinated side-on to the metal; the bonding features correspond to the metallocyclopropene type with WC bond lengths of 200 and 203 pm, respectively, and CC bond length of 125 pm.

Catalytic activity of some immobilized dirhodium complexes with one bridging thiolato and one bridging chloro ligand

Several μ-thiolato-μ-chlorodicarbonylbis(tri-t-butylphosphine)dirhodium complexes were anchored (a) to diphenylphosphinated crosslinked polystyrene by phosphine ligand exchange, (b) to chloromethylated polystyrene resin by substitution of the benzylic halogen via the μ-thiolato group, and (c) to silica and alumina via a sulfur-attached -CH 2CH 2SiO 3bridge. The catalytic activity of the various immobilized dirhodium complexes in allylic isomerization, hydrogenation and hydroformylation processes were investigated. Some mechanistic features of these catalyses are discussed.

Neutral and anionic 2-methyl-6-nitrophenyl palladium(II) complexes. The X-ray crystal structure of bis(benzyltriphenylphosphonium)trans-di-µ-chloro-bis[chloro(2-methyl-6-nitrophenyl)palladate(II)]–acetone (1/2)

By reacting HgR2(R = C6H3Me-2,NO2-6) with [PPh3(CH2Ph)]2[Pd2Cl4(µ-Cl)2](2 : 1) in refluxing acetone the complex trans-[PPh3(CH2Ph)]2[Pd2Cl2(µ-Cl)2R2]·2Me2CO (1) crystallizes in high yield. The anion is a centrosymmetric dimer with both palladium atoms having square-planar co-ordination. The mutually trans chloro ligpnds, one terminal and the other bridging, have similar Pd–Cl bond lengths [2.322(4) and 2.334(4)A, respectively], both being shorter than the other Pd–Cl bonds [2.448(4)A] corresponding to the bridging chloro ligands trans to the phenyl groups. The angles between the phenyl rings and the ‘PdCl2(µ-Cl)2’ moiety plane or their own nitro group planes are 73.3 or 140.2°, respectively. The shortest Pd–O distance [2.893(6)A] is too long to assume intramolecular bonds. This complex is the first aryl palladium derivative of such a stoicheiometry described so far. From its solutions in dimethyl sulphoxide (dmso) the complex [PdCl2(R)(dmso)]– can be isolated. Complex (1) also reacts with PPh3(1 : 4) or bidentate ligands (1 : 2) to form trans-[PdCl(R)(PPh3)2] or cis-[PdCl(R)(L–L)](L–L = 2,2′-bipyridine or 1,10-phenanthroline) respectively.

Symmetrisch substituierte butadiinkomplexe von wolfram(IV)

Summary The butadiyne complexes [W 2 Cl 8 (Me 3 SiC≡CC≡CSiMe 3 )] x and [W 2 Cl 8 (IC≡CC≡CI)] x are synthesized by the reaction of tungsten hexachloride with Me 3 SiC≡CC≡SiMe 3 and IC≡CC≡CI, respectively, in boiling CCl 4 . The complexes are associated by chloro bridges WCl 2 W. They react with pyridine or diethyl ether to form the adducts [W 2 Cl 8 (XC≡CC≡CX)Y 2 ] (X = SiMe 3 , I; Y = pyridine, diethyl ether). The thermally and mechanically very stable diiodobutadiyne complex reacts with (PPh 3 CH 2 I)Cl forming the chloro complex (PPh 3 CH 2 I) 2 [W 2 Cl 10 (IC≡CC≡CI)] which is very soluble in dichloromethane. This chloro complex reacts with silver chloride to form the dichlorobutadiyne complex (PPh 3 CH 2 I) 2 [W 2 Cl 10 (ClC≡CC≡CCl)] which is also very stable. The results of IR and 13 C NMR spectra correspond to the carbon-carbon triple bonds acting as four-electron donors, and the bonding to tungsten is best described as being of the metallacyclopropene type.

Synthesen und Kristallstrukturen von PPh4[RuCl4(NO)(NSCl)] und (PPh4)2[RuCl4(NS)]2·4C H2Cl2 / Syntheses and Crystal Structures of PPh4[RuCl4(NO)(NSCl)] and (PPh4)2[RuCl4(NS)]2·4C H2Cl2

Abstract By reaction of trithiazylchloride, (NSCl)3, with PPh4[RuCl4(NO)]2 in dichloromethane the thiazylchloridenitrosyl complex PPh4[RuCl4(NO)(NSCl)] is obtained; its vacuum pyrolysis at 200-220 °C yields the thionitrosyl com plex (PPh4)2[RuCl4(NS)]2 which crystallizes from CH2Cl2 solution with four molecules of CH2Cl2. Both com pounds were charaterized by their IR spectra and by X-ray crystal structure determinations. Crystal data: PPh4[RuCl4(NO)(NSCl)], mono­clinic, space group P 21/n, Z = 4, a = 982.6, b = 1700.0, c = 1772.3 pm , β = 104.79° (2548 observed reflexions, R = 0.046); (PPh4)2[RuCl4(NS)]2·4CH2Cl2, triclinic, P1̄ , Z = 1, a = 952.9, b = 1380.0, c = 1458.5 pm , α = 112.91, β = 106.67, γ = 92.61° (3760 observed reflexions, R = 0.053). In the [RuCl4(NO)(NSCl)]⊖ ion the nitrosyl and thiazyl chloride ligands occupy ex ­ positions; bond lengths indicate double bonds in the linear Ru=N=O group, while the NSCl molecule is attached by a donor-acceptor interaction Ru-N≡S̲-Cl , although with a rather short Ru-N bond of 198 pm (N≡S 144 pm, S-Cl 213 pm). The centrosymmetric [RuCl4(NS)]2 2⊖ ions have chloro bridges and NS ligands in axial positions; the nearly linear Ru=N=S group has bond lengths Ru=N 175 pm and N=S 147 pm.

Unsymmetrisch substituierte alkin- und dialkinkomplexe von wolfram(IV) und molybdän(IV). Die kristallstruktur von [W 2Cl 8(PhCCCCSiMe 3)(pyridin) 2

The unsymmetrically substituted alkyne ClCCSiMe 3 and the dialkynes PhCCCCSiMe 3 and PhCCSiMe 2CCPh react with tungsten hexachloride in CCl 4, in the presence of C 2Cl 4 as a reducing agent, and with molybdenum pentachloride in CCl 4, respectively, to form the alkyne complexes [MoCl 4-(ClCCiMe 3)] 2 ( 1), [WCl 4(ClCCSiMe 3)] 2 ( 2), [WCl 4(PhCCCCSiMe 3)] 2 ( 3), [W 2Cl 8(PhCCCCSiMe 3)] x ( 4), [W 2Cl 8(PhCCSiMe 2CCPh)] x ( 5), [Mo 2Cl 8-(PhCCSiMe 2CCPh)] x ( 6). In all cases the alkyne ligand is side-on coordinated to the metal (η 2), the bonding features correspond to the cyclopropene type. The coordination number of the metal is 7; the complexes 1–3 are dimerised via MCl 2M bridges and the bifunctional complexes 4–6 are polymerised via analogous bridges. In 3, the tungsten atom is coordinatd to the alkyne group adjacent to the phenyl substituent. In the molybdenum compounds the alkyne ligand is cleaved with Lewis bases such as pyridine or diethyl ether forming solvate complexes of molybdenum(IV), whereas in the corresponding tungsten complexes only the chloro bridges are cleaved. The pyridine adducts [W 2Cl 8(PhCCCCSiMe 3)(pyridine) 2] ( 7) and [W 2Cl 8(PhCCSiMe 2CCPh)(pyridine) 2] ( 8) are described in further detail. All complexes are characterized by elemental analyses, mass and IR spectra, the tungsten compounds (as ether adducts) also by their 13C NMR spectra. 7 was obtained in single crystals and has been subjected to a X-ray diffraction study. It crystallises in the monoclinic space group P2 1/ c with four formula units per unit cell (4154 independent, observed reflexions, R = 0.096) and with the lattice constants a 880.0(6), b 2866.0(20), c 1501.2(10) pm; β 94.4(3)°. EAch tungsten atom is surrounded by four chlorine atoms in equatorial positions, both alkyne groups are bonded side-on (η 2) to the tungsten atoms, whereas the N atoms of the pyridine molecules are located trans to the alkyne groups. The CC bond lengths of the alkyne groups are 125 pm (adjacent to the phenyl substituent) and 140 pm (adjacent to the SiMe 3 group), respectively. A strong trans-effect of the two alkyne groups is observed, resulting in shifting the tungsten atoms out of the Cl 4 planes by about 33 pm. The dihedral angle of 94.9°, enclosed by the two WC 2 planes, is remarkable.

Chloronitrosylkomplexe von Ruthenium(II) Die Kristallstruktur von (PPh3Me)2[Ru(NO)Cl4]2-2 CH2Cl2 / Chloro Nitrosyl Complexes of Ruthenium (II) The Crystal Structure of (PPh3Me)2 [Ru(NO)Cl4]2 • 2 CH2Cl2

Abstract Ruthenium trichloride, obtained from its hydrate with thionyl chloride, reacts with excess trichloronitrom ethane yielding polymer [Ru(NO)Cl3]; by addition of triphenylmethylphosphonium chloride in dichlorom ethane (PPh3Me)2[Ru(NO)Cl4]2 · 2 CH2Cl2 is obtained, the IR spectrum of which is reported and assigned. Its crystal structure was determined with X-ray diffraction data (6404 independent observed reflexions, R = 0.068). Crystal data at -90 °C: a = 1145, b = 1591, c = 1406 pm, β = 96,0°, Z = 2, space group P21/C. The structure consists of PPh3Me⊕ cations, centrosymmetric anions [Ru(NO)Cl4]2 2⊖ nearly fulfilling C2h symmetry, and CH2Cl2 molecules. In the anions the Ru atoms are linked via chloro bridges; the nitrosyl groups occupy axial positions with bond distances RuN of 175 and NO of 113 pm, bond angle RuNO 172.7°.

Catalytic activity of some homogeneous and silica-bound dirhodium complexes having one bridging thiolato and one bridging chloro ligand

Several μ-alkylthiolato- and μ-arylthiolato-μ-chloro-dicarbonylbis(tri-t-butylphosphine) dirhodium complexes, Rh 2(CO) 2(P[C(CH 3) 3]3) 2(μ-Cl)(μ-SR) 3 – 8, were shown to be effective catalysts for hydrogenation, hydroformylation and isomerization of olefins. Silica-attached versions of these complexes, in which the sulfur was linked to the support by a (CH 2) n SiO 3 ( n = 2, 3) bridge, could be recycled for use in further runs. Both the homogeneous and the heterogenized catalysts were shown to retain the dinuclear structure during and after the catalytic processes.

Cyclo-thiazenokomplexe von Molybdän und Wolfram. Die Kristallstruktur von AsPh4[WCl4(N3S2)] / Cyclo-thiazeno Complexes of Molybdenum and Tungsten. The Crystal Structure of AsPh4[WCl4(N3S2)

The dark brown cyclo-thiazeno com plexes [MoCl3(N3S2)]2 and [WCl3(N3S2)]2 are obtained by quantitative reactions of MoNCl3 with (NSCl)3 and of WOCl4 or WSCl4 with excess (NSCl)3, respectively. They are diamagnetic, thermally stable up to 200 °C, and only slightly sensitive towards moist air, but react explosively with aqueous bases. According to the IR spectra [MoCl3(N3S2)]2 is dimerized via chloro bridges whereas the tungsten com pound is associated via the γ-nitrogen atoms of the cyclo-thiazeno ligand. By reaction with [AsPh4]Cl or [PPh4]Cl in CH2Cl2, the compounds EPh4[MCl4(N3S2)] are obtained (E = P, As; M = Mo, W). The crystal structure of AsPh4[WCl4(N3S2)] was determined from X-ray diffraction data (1845 observed reflexions, R = 0.045). It crystallizes in the monoclinic space group P21/c with four formula units per unit cell. The lattice constants are a = 1352.4, b = 968.4, c = 2393.8 pm and β = 115.1°. The com pound is built up from AsPh4 ⊕ cations and [WCl4(N3S2)]⊖ anions in which the W atoms are coordinated in a distorted octahedral fashion by four Cl and two N atoms of the N3S2 ligand. The WN bond lengths (182 and 188 pm) correspond to douple bonds. The WN3S2 ring is planar and has SN bond lengths between 154 and 161 pm.

Unexpected formation and molecular structure of a stable dinuclear rhodium compound with a single chloro bridge, [cyclic]-(CO)2ClRh(.mu.-Cl)Rh(CO)[C6H5P(OCMe2CH2)2NH

La reaction de [Rh(CO) 2 Cl] 2 avec l'aminophosphorane bicyclique H(C 6 H 5 ) P[OC(CH 3 ) 2 CH 2 ] 2 N est etudiee du point de vue de sa stœchiometrie. Structure du compose inattendu obtenu

Cobalt(II) and nickel(II) coordination compounds derived from 3,3′, 5,5′-tetramethyl-4,4′-bi-1H-pyrazole, 3,3′, 5,5′-tetramethyl-4,4′ methylene-bis-1H-pyrazole and 4,4′-methylene-bis-1 H-pyrazole

The bidentate ligands 3,3′,5,5′-tetramethyl-4,4′-bi-1H-pyrazole (tmbpz) 3,3′,5,5′-tetramethyl-4-4′-methylene-bis-1H-pyrazole (tmmbpz) and 4,4′ methylene-bis-1H-pyrazole (mbpz) react with cobalt(II) and nickel(II) chlorides to give complexes with the formula MCl 2(LL) (M = Co, LL = tmmbpz; tmmbpz; M = Ni, LL = tmmbzp or MCl 2(LL) 2 (M = Co, LL = mbpz; M = Ni, LL = tmbpz, tmmbpz, mbpz). Similarly the reactions of tmbpz and tmmbpz with cobalt(II) and nickel(II) nitrates give complexes of formula M(NO 3) 2(LL) (M = Co, LL = tmmbpz) or M(NO 3) 2(LL) 2 (M = Co, Ni; LL = tmbpz, tmmbpz). The reaction products are generally independent of the molar ratio (M:LL) of reactants, except in the reactions of tmmbpz with nickel(II) chloride and cobalt(II) nitrate. The CoX 2(LL) complexes are pseudotetrahedral species, whereas NiCl 2(tmmbpz) seems to contain five-coordinate dimeric units bonded through two bridging chloro ligands. The MX 2(LL) 2 complexes are pseudo-octahedral species; some of them are clearly tetragonally distorted, particularly the chlorides. Dimeric or polymeric structures were proposed for the complexes with bridging bipyrazole molecules, as a consequence of the bidentate, non-chelating nature of the ligands.