Syntheses and crystal structures of the closo-borates M2[B7H7] and M[B7H8] (M = PPh4, PNP, and N(n-Bu4)): the missing crystal structure in the series [B(n)H(n)]2- (n = 6-12)

Oxidation of [N(n-Bu(4))](2)[B(9)H(9)] with oxygen in a mixture of dimethoxyethane and CH(2)Cl(2) leads to salts of the [B(7)H(7)](2-) dianion. This is the first convenient synthesis for a seven-vertex hydro-closo-borate anion. Protonation with NEt(3)·HCl resulted in salts of the [B(7)H(8)](-) monoanion. Both closo-borate anions were isolated and characterized by (1)H, (1)H{(11)B}, (11)B, and (11)B{(1)H} NMR spectroscopy. The temperature-dependent (1)H{(11)B}, (11)B, and (11)B{(1)H} NMR spectra of [B(7)H(8)](-) were also measured. The structure of [B(7)H(7)](2-) as well as of [B(7)H(8)](-) were determined by single-crystal X-ray diffraction.     

A bi-butterfly W-Cu-S cluster compound:Synthesis and crystal structure of(n-Bu_4N)_2[W_2Cu_4S_8(S_2CNC_4H_8)_2]

The compound(n-Bu_4N)_2[W_2Cu_4S_8(S_2CNC_4H_8)_2]was obtained by the reaction of Bu_4NBr,(NH_4)_2WS_4,NaS_2NCC_4H_8 and CuCl in CH_3CN and CH_3OH.It crystallizes in the monoclinicspace group P2_1/c with unit cell parameters:a=21.875(5),b=16.843(4),c=17.745(5),β=101.69(6)°,V=6402(6)~3,Z=4,D_o=1.718 g·cm~(-3).The final R and R_w values converged to 0.055and 0.060 respectively.The structure consists of two‘butterfly’units[WS_4Cu_2]linked togetherby two weak Cu—S bonds and two bridging S_2CNC_4H_8 ligands.Infrared spectra gave charac-teristic absorptions at 495 cm~(-1) for W=S and 450,435,412 cm~(-1) for W—μ-S.     

Synthesen und Kristallstrukturen von [Pd9As8(PPh3)8] und [Pd9Sb6(PPh3)8]

Syntheses and Crystal Structures of [Pd₉As₈(PPh₂)₈] and [Pd₉Sb₆(PPh₃)₈] [PdCl₂(PPh₃)₂] reacts with As(SiMe₃)₃ to give the new cluster [Pd₉As₈(PPh₃)₈] ( 4 ). 4 has been characterized by X-ray crystal structure analysis. It is a molecule in which four [Pd₂(PPh₃)₂]-units are bridged by As₂-units. A further Pd atom is located in the centre of the cluster. 4 crystallizes in the space group C2/c with four formula units per unit cell. The lattice constants at 200 K are: a = 3 970.6(3), b = 1 648.90(16), c = 3 266.30(20) pm, β = 131,44(4)°. The reaction of [PdCl₂(PPh₃)₂] with Sb(SiMe₃)₃ yields [Pd₉Sb₆(PPh₃)₈] ( 5 ). 5 consists of a body centred cubic Pd₉-cluster. All of the cube faces are capped by μ₄-Sb-ligands. 5 crystallizes in the space group Pn3 with two formula units per unit cell. The lattice constants at 200 K are: a = b = c = 1 995.4(2) pm.     

The Binary Group 4 Azides [PPh4]2[Zr(N3)6] and [PPh4]2[Hf(N3)6]

The binary zirconium and hafnium polyazides [PPh₄]₂[M(N₃)₆] (M=Zr, Hf) were obtained in near quantitative yields from the corresponding metal fluorides MF₄ by fluoride–azide exchange reactions with Me₃SiN₃ in the presence of two equivalents of [PPh₄][N₃]. The novel polyazido compounds were characterized by their vibrational spectra and their X‐ray crystal structures. Both anion structures provide experimental evidence for near‐linear M‐N‐N coordination of metal azides. The species [M(N₃)₄], [M(N₃)₅]^? and [M(N₃)₆]^2? (M=Ti, Zr, Hf) were studied by quantum chemical calculations at the electronic structure density functional theory and MP2 levels.     

The decompositions of metastable [C4H8O]+˙ ions and the [C4H8O]+˙ potential surface

Collisionally activated decomposition (CA) spectra of [C₄H₈O]⁺˙ ions and the products of their metastable decompositions are used to refine a previously presented picture of the reactions of [C₄H₈O]⁺˙ ions. Metastable [C₄H₈O]⁺˙ isomers predominantly rearrange to the 2-butanone ion and decompose by loss of methyl and ethyl, although up to 38% of the methyl losses take place by other pathways to form \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{2}} = {\rm{CHCH = }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H}}{\rm{.}} $\end{document} . The CA spectra of many of the [C₄H₈O]⁺˙ ions with the oxygen on the first carbon are very similar, consistent with those ions isomerizing largely to common structures before or after collision. However, several of these ions have unique CA spectra, so they must remain structurally distinct from the majority of the [C₄H₈O]⁺˙ ions below energies required for decomposition. The CA spectra of ions with the oxygen on the second carbon are distinct from those of ions with the oxygen on the first carbon, so there is limited interconversion of the non-decomposing forms of the two types of ions. A potential energy diagram for the reactions of metastable [C₄H₈O]⁺˙ ions is constructed from appearance energy measurements. As would be expected, the relative importances of most of the [C₄H₈O]⁺˙ isomerizations seem to be inversely related to the activation energies for those processes. Some parallels between the isomerizations of [C₄H₈O]⁺˙ ions and those of related ions are pointed out.     

Syntheses and Crystal Structures of Complexes [Cu(C14H8N3O4Br)](C4H9NO) and [Ni(C14H9N2O3Br)](C4H9NO)

The title compounds, Cu(L1)(C4H8NHO) and Ni(L2)(C4H8NHO) (H2L1 = 5-bro- mosalicylaldehyde-p-nitrobenzoylhydrazone, H2L2 = 5-bromosalicylaldehyde-p-hydroxybenzo- ylhydrazone), have been obtained and characterized by single-crystal X-ray diffraction. Complex 1 belongs to the triclinic system, space group P1 with a = 8.6960(2), b = 9.957(2), c = 11.878(2) , α = 73.36(3), β = 78.25(3), γ = 82.64(3)o, V = 962.1(3) 3, Mr = 512.81, Z = 2, F(000) = 514, Dc = 1.770 g/cm3, μ(MoKα) = 3.251, R = 0.0337 and wR = 0.0846. Complex 2 is of monoclinic, space group P21/c with a = 13.313(2), b = 8.2096(1), c = 21.890(3) , β = 125.737(3)o, V = 1941.9(4) 3, Mr = 478.97, Z = 4, F(000) = 968, Dc = 1.638 g/cm3, μ(MoKα) = 3.085, R = 0.0356 and wR = 0.0817. The ligands form a satisfactory N2O2 square plane around the metal centers in two compounds. Different patterns of hydrogen bonds are observed owing to the presence of different substituents on aromatic ring of the acylhydrazone Schiff bases. In complex 1, square-planar copper(II) complexes are linked by intermolecular hydrogen bonds leading to zigzag infinite chains. In complex 2, the metal complexes are linked via hydrogen bonds to form corrugated sheets in a staggered fashion; 3D channels along the b axis are constructed through other non-covalent interactions between the neighboring layers.     

钼(钨)/铜/硫三核簇合物[A]2[MS4(CuCN)2] (M=Mo,W;A=Et4N,PPh4)的合成及晶体结构

合成了四个三核簇合物[A]2[MS4(CuCN)2](1A＝Et4N,M＝Mo;2A＝PPh4,M＝W;3A＝Et4N,M＝W;4A＝PPh4,M＝Mo),测定了[Et4N]2[MoS4(CuCN)2]*H2O(1*H2O)和[PPh4]2[WS4(CuCN)2]*0.5DMF*H2O(2*0.5DMF*H2O)的晶体结构.1和2的簇阴离子[MS4(CuCN)2]2-(M＝Mo,W)均具有一个双齿配体MS42-和两个CuCN形成的近似D2d对称性结构.     

Photoionization of the C-1?C-4 monosubstituted alkyl benzenes: Thermochemistry of [C7H7]+ and [C8H9]+ formation

The appearance energies for the [C₇H₇]⁺ and [C₈H₉]⁺ fragment ions produced in the fragmentation of the C-1? C-4 monosubstituted alkyl benzenes have been measured by photon impact. The mean heat of formation calculated for [C₇H₇]⁺ is 205.3 ± 1.9 kcal mol^?1 which is consistent with a threshold tropylium structure. For [C₈H₉]⁺ the mean heat of formation is calculated to be 199.2 ± 1.3 kcal mol^?1 which can be equated with either a methyl tropylium or α-phenylethyl structure at threshold. Some evidence is provided for the existence of the α-phenylethyl ion.     

1-D and 2-D homoleptic dicyanamide structures, [Ph4P]2[CoII[N(CN)2]4] and [Ph4P][M[N(CN)2]3] (M = Mn, Co)

The homoleptic complexes [Ph(4)P](2)[Co[N(CN)(2)](4)] and [Ph(4)P][M[N(CN)(2)](3)] [M = Co, Mn] have been structurally as well as magnetically characterized. The complexes containing [M[N(CN)(2)](4)](2-) form 1-D chains, which are bridged via a common dicyanamide ligand in [M[N(CN)(2)](3)](-) to form a 2-D structure. The five-atom [NCNCN](-) bridging ligands lead to weak magnetic coupling along a chain. The six [NCNCN](-) ligands lead to a (4)T(1g) ground state for Co(II) which has an unquenched spin-orbit coupling that is reflected in the magnetic properties. Long-range magnetic ordering was not observed in any of these materials.     

Syntheses,crystal structures and spectroscopic properties of the novel complexes [M(MOBPT)*2 (H2O)2](ClO4)2 · 4H2O (M = CoII and NiII)

The novel cobalt(II) and nickel(II) complexes with 4-(p-methoxyphenyl)-3,5-bis(pyridin-2-yl)-1,2,4-triazole (MOBPT) have been synthesized and their molecular structures determined by X-ray analysis, i.r. and by ESI-MS spectroscopy. The metal atom is in a distorted octahedral environment. Two bidentate chelating ligands (MOBPT) coordinate to the metal center equatorially and two water molecules coordinate axially. Each MOBPT entity coordinates via one triazole nitrogen and one pyridine nitrogen atom. Magnetic measurements show that the complexes are high-spin species in the 75–300 K range.     

About the Keggin isomers: crystal structure of [N(C4H9)4]-gamma-[SiMo2W10O40]n- (n= 4 or 6)

The tetrabutylammonium gamma-dodecatungstosilicate has been crystallized in a 6/1 acetonitrile/water solvent. An X-ray single-crystal analysis was carried out on [N(C4H9)4]4-gamma-[SiW12O40] which crystallizes in the orthorhombic system, space group P2(1)2(1)2(1), with a = 19.0881(3) A, b = 21.4435(3) A, c = 26.0799(1) A, V = 10674.9(2) A3, Z = 4, and rho(calcd) = 2.392 g/cm3. The idealized C2v arrangement of the anion results from the rotation of 60 degrees of two trigonal [W3O13] groups in the Keggin anion. Taking as reference the geometrical characteristics of the Keggin anion, it appears that the bond lengths and bonds angles within the four [W3O13] groups are not significantly modified while the mu-oxo junctions between the two rotated groups and those between the two unrotated groups involve more acute and opened W-O-W angles, respectively. The syntheses and 183W NMR characterizations of the mixed gamma-[SiW10Mo2O40]n- compounds corresponding to the oxidized (Mo(VI); n = 4) and to the two electron-reduced (Mo(V); n = 6) anions are reported. Structural analysis by 183W NMR has proved unambiguously that the C2v structure of the gamma-[SiW10O36]8- subunit is retained in both the compounds. The electronic behavior of the series gamma-[SiW10M2E2O36]6- (M = Mo or W; E = O or S) is examined, compared and related to 183W NMR data.     

The first examples of metal-mediated addition of a phosphorus imine to nitriles; the preparation and X-ray crystal structures of [PtCl4{NH=C(Et)N=PPh3}2] and [PtCl2(EtCN){NH=C(Et)N[double bond, length as m-dash]PPh3}

Imino(triphenyl)phosphorane, Ph3P=NH (1), reacts with nitrile complexes of Pt(IV) to generate hydrolytically sensitive [PtCl4{NH=C(R)N=PPh3}2](R=Me 2a, Et 2b, Ph 2c), and with the Pt(II) complex [PtCl2(EtCN)2] to give [PtCl2(EtCN){NH=C(Et)N=PPh3}](3) and [PtCl2{NH=C(Et)N=PPh3}2](4); X-ray crystallography performed upon (2b) and (3) confirms the presence of an imine/nitrile addition ligand bound by the terminal nitrogen.     

Synthesis of monohalogeno derivatives of closo-[B9H9]2-. Crystal structures of (Ph4P)2[1-XB9H8].CH3CN (X = Cl, Br, I)

By reaction of Na2[B9H9] with the appropriate N-halogenosuccinimide, the monohalogenated anion [1-XB9H8]2- (X = Cl, Br, or I) is formed. The X-ray diffraction analyses performed on single crystals of (Ph4P)2[1-XB9H8].CH3CN (X = Cl, Br, I) reveal that the tricapped trigonal prismatic geometry of the cluster is retained after substitution in the 1-position. Crystallographic data are as follows for (Ph4P)2[1-XB9H8].CH3CN. X = Cl, Br: monoclinic, space group P2(1), a = 10.7 A, b = 32.9 A, c = 13.8 A, beta = 96 degrees, Z = 4, R1 = 0.038 and R1 = 0.036, respectively. X = I: monoclinic, space group P2(1)/n, a = 10.5 A, b = 13.6 A, c = 33.4 A, beta = 94 degrees, Z = 4, R1 = 0.094. The compounds have been characterized by vibrational and 11B NMR spectroscopy as well.     

Syntheses, X-ray crystal structures, and magnetic properties of novel linear M2[II]U[IV] complexes (M=Co, Ni, Cu, Zn)

Attempts to prepare heterobimetallic complexes in which 3d and uranium magnetic ions are associated by means of the Schiff bases H(2)L(i) derived from 2-hydroxybenzaldehyde or 2-hydroxy-3-methoxybenzaldehyde were unsuccessful because of ligand transfer reactions between [ML(i)] (M=Co, Ni, Cu) and UCl(4) that led to the mononuclear Schiff base complexes of uranium [UL(i)Cl(2)]. The crystal structure of [UL(3)Cl(2)(py)(2)] [L(3)=N,N'-bis(3-methoxysalicylidene)-ethylenediamine; py=pyridine] was determined. The hexadentate Schiff base ligand N,N'-bis(3-hydroxysalicylidene)-2,2-dimethyl-1,3-propanediamine (L) was useful for the synthesis of novel trinuclear complexes of the general formula [[ML(py)](2)U] (M=Co, Ni, Zn) or [[CuL(py)]M'[CuL]] (M'=U, Th, Zr) by reaction of [M(H(2)L)] with [M'(acac)(4)] (acac=MeCOCHCOMe). The crystal structures of the Co(2)U, Ni(2)U, Zn(2)U, Cu(2)U, and Cu(2)Th complexes show that the two ML fragments are orthogonal, being linked to the central actinide ion by the two pairs of oxygen atoms of the Schiff base ligand. In each compound, the UO(8) core exhibits the same dodecahedral geometry, and the three metals are linear. The magnetic study indicated that the two Cu(2+) ions are not coupled in the Cu(2)Zr and Cu(2)Th compounds. The magnetic behavior of the Co(2)U, Ni(2)U, and Cu(2)U complexes was compared with that of the Zn(2)U derivative, in which the paramagnetic 3d ion was replaced with the diamagnetic Zn(2+) ion. A weak antiferromagnetic coupling was observed between the Ni(2+) and the U(4+) ions, while a ferromagnetic interaction was revealed between the Cu(2+) and U(4+) ions.     

The isomerization mechanism of alkylamines: Structure of [C2H6N]+ and [C3H8N]+ fragment ions

The MIKE spectra of amines RCH₂NH₂ containing more than five carbon atoms exhibit m/z 44 and m/z 58 peaks. The structures of these [C₂H₆N]⁺ and [C₃H₈N]⁺ ions have been established by collisional activation spectra. The results are in agreement with the fragmentation mechanisms previously proposed.     

The syntheses,crystal, molecular and electronic structures of two polymorphs of [ReCl2(N2COPh)(C3N2H4)(PPh3)2] and [ReCl2(N2COPh)(py)(PPh3)2] complexes

The [ReCl₂(η²-N₂COPh–N^′,O)(PPh₃)₂] complex reacts with pyridine and pyrazole to give [ReCl₂(N₂COPh)(py)(PPh₃)₂] and [ReCl₂(N₂COPh)(C₃N₂H₄)(PPh₃)₂], respectively. Two monoclinic polymers of [ReCl₂(N₂COPh)(C₃N₂H₄)(PPh₃)₂] and [ReCl₂(N₂COPh)(py)(PPh₃)₂] have been characterized by IR, UV–Vis, ¹H NMR, magnetic measurements and X-ray structure.     

Mass spectrometry of pyridine compounds–IV: The formation and decomposition of the [M – methyl]+ ion [C8H10N]+ from 4-t-butylpyridine in comparison with that of the [M – methyl]+ ion [C9H11]+ from t-butylbenzene,as studied by D- and 13C-labelling

A strong secondary isotope effect is observed in the preferred loss of methyl vs. trideutero-methyl from the molecular ions of appropriately labelled 4-t-butylpyridine and t-butylbenzene decomposing in the first and second field free regions of a double focusing mass spectrometer. This has been rationalised by invoking the theory of radiationless transitions², which can account for the higher population of activated states responsible for loss of methyl vs. that for trideuteromethyl. ¹³C-Labelling at the central carbon atom of the t-butyl group indicates that the [M – methyl]⁺ ions, decomposing further by elimination of ethylene, cannot be represented exclusively by a pyridylated (or phenylated) cyclopropane ion if present at all. It is concluded that ions with structures generated by 1,2-hydrogen-, 1,2-pyridyl- (or 1,2-phenyl-) and 1,2-methyl shifts must also play a role. D-labelling further shows an extensive randomisation of side-chain hydrogen atoms in the [M-methyl]⁺ ions of 4-t-butylbenzene; in this case, however, the expelled ethylene also contains ring hydrogen atoms (≤2). Presumably this is caused by exchange between the side-chain and ortho-hydrogen atoms in the initially generated phenyldimethylcarbinyl carbenium ion.     

Photodissociation of gaseous [C4H5N]+˙ ions

The photodissociation of [C₄H₅N]⁺˙ ions generated by ionization of pyrrole (1), allyl cyanide (2), crotonitrile (3), cyclopropyl cyanide (4) and methacrylonitrile (5) has been studied using ion beam techniques. At least four different stable ion structures have been distinguished, which is in contrast to earlier CAD studies. In addition it has been shown that [C₂H₃N]⁺˙ fragment ions formed by dissociative ionization of the same precursors have structures which are distinct from that of ionized acetonitrile.