Synthesis and characterization of stable osmafuran starting from HC≡CCH(OH)C≡CH and OsHCl(CO)(PPh3)3

This paper presents a new convenient route to prepare osmafuran starting from readily accessible HC≡CCH(OH)C≡CH and OsHCl(CO)(PPh₃)₃. Treatment of a solution of OsHCl(CO)(PPh₃)₃ in dichloromethane with HC≡CCH(OH)C≡CH, followed by the addition of acetic acid, produced osmafuran [Os(CHC(PPh₃)CO(CH₂CH₃))Cl(CO)(PPh₃)₂]Cl (2). 2 has been isolated in good yield and fully characterized. ¹H and ¹³C NMR spectra show the characteristic downfield chemical shifts of the ring hydrogen and carbon atoms. NMR and X-ray diffraction data provide strong evidence for the aromatic nature of 2. Probably due to the effect of the phosphonium substituent, 2 exhibits remarkable thermal stability, air stability and lower reactivity.

     

Reactivity of RuCl(2)(CO)(P(t)()Bu(2)Me)(2) toward H(2) and Brønsted Acids: Aggregation Triggered by Protonation and Phosphine Loss

Reaction of H(2) with RuCl(2)(CO)L(2) (L = P(t)()Bu(2)Me) in benzene forms RuHCl(CO)L(2) and HCl. The latter reacts with RuCl(2)(CO)L(2) to give [LH][Ru(2)Cl(5)(CO)(2)L(2)] and [LH]Cl. The Ru(2)Cl(5)(CO)(2)L(2)(-) ion is detected (NMR) as several isomers, and is shown by X-ray diffraction to have a face-shared bioctahedral structure: LCl(OC)Ru(&mgr;-Cl)(3)Ru(CO)ClL(-). The loss of phosphine from Ru(II) is triggered by electrophilic attack, but not directly on P or on the Ru-P bond. It is shown (low-temperature NMR studies) that HCl reacts with RuHCl(CO)L(2) to give initially RuCl(2)(H(2))(CO)L(2), in which H(2) is trans to Cl. From this study, and also direct observation of the reaction of HCl with RuCl(2)(CO)L(2) to produce Ru(2)Cl(5)(CO)(2)L(2)(-), the Br?nsted basicity of chloride in RuCl(2)(CO)L(2) is established. This accounts for its reaction with PhC(2)H and NEt(3) to give Ru(C(2)Ph)Cl(CO)L(2). Crystallographic data (-173 degrees C) for [P(t)()Bu(2)MeH][Ru(2)Cl(5)(CO)(2)(P(t)()Bu(2)Me)(2)]: a = 16.418(2)?, b = 12.578(2)?, c = 20.044(3)?, beta = 103.38(1) degrees with Z = 4 in space group P2(1)/a.     

Intramolecular Rearrangements of >Si(O–C·=O)(CH2–CH3) and >Si(CH2–CH·–CH3)(CH2–CH3) Radicals

Using ESR and IR spectroscopy, the structures of >Si(O–C^·=O)(CH₂–CH₃) (1) and >Si(CH₂–CH^·–CH₃)(CH₂–CH₃) (2) radicals were deciphered. The directions and kinetic parameters of reactions of intramolecular rearrangements in these radicals were determined. The reactions of hydrogen atom abstraction in radical (1) from the CH₂ and CH₃ groups were studied. It was found that the endothermic reaction of hydrogen atom abstraction from the methyl group occurs at a higher rate than the exothermic reaction with the methylene group. The differences are determined by changes in the size of a cyclic transition state. Based on the experimental data, the strengths of separate C–H bonds in surface fragments are compared. The rearrangement >Si(CH₂–CH^·–CH₃)(CH₂–CH₃) >Si(C^·(CH₃)₂)(CH₂–CH₃) was discovered and its mechanism was determined. One of its steps is the skeletal isomerization Si- (2)- _. (1)Si- (1)- _. (2). Experimental data are analyzed using the results of quantum-chemical calculations of model systems.     

A new disilene with π-accepting groups from the reaction of disilyne RSi≡SiR (R = Si(i)Pr[CH(SiMe3)2]) with isocyanides

The reaction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasila-2-yne (1) with tert-butylisocyanide or tert-octylisocyanide produced the corresponding disilyne-isocyanide adducts [RSiSiR(CNR')(2)] (R = Si(i)Pr[CH(SiMe(3))(2)](2), R' = (t)Bu (2a) or CMe(2)CH(2)(t)Bu (2b)), which are stable below -30 °C and were characterized by spectroscopic data and, in the case of 2a, X-ray crystallography. Upon warming to room temperature, 2 underwent thermal decomposition to produce 1,2-dicyanodisilene R(NC)Si═Si(CN)R (3) and 1,2-dicyanodisilane R(NC)HSiSiH(CN)R (4) via C-N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative 3 was characterized by X-ray crystallography.     

Crystal Structures of [Ni(Phen)(i‐Bu2PS2)2] and [Ni(Phen)3](i‐Bu2PS2)2 Complexes and Interaction between Coordinated 1,10‐Phenanthroline Molecules

Single crystals of [Ni(Phen)(iBu₂PS₂)₂] (I) and [Ni(Phen)₃](iBu₂PS₂)₂ (III) compounds were grown, and their structures were determined by Xray diffraction analysis (CAD4 diffractometer, MoK radiation, 3336 F _hkl , R = 0.0373 for I and 2575 F _hkl for III). The crystals of complex I have a triclinic unit cell with the following parameters: a = 11.097(1) , b = 14.903(2) , c = 22.650(3); = 75.18(1)°, = 80.50(1)°, = 75.07(1)°, V = 3479.2(7)³, Z = 4, _calc = 1.255 g/cm³, and space group 1; the crystals of III have a monoclinic unit cell with the following parameters: a = 19.010(3), b = 15.481(1) , c = 17.940(3); = 97.58(1)°, V = 5233.5(12)³, Z = 4, _calc = 1.292 g/cm³, and space group C2/c. The structure of complex I is built from mononuclear molecules, and the structure of III, from [Ni(Phen)₃]²⁺ complex cations and i Bu₂PS₂ ^- outersphere anions. The NiN₂S₄ coordination polyhedra in the structure of I and NiN₆ in the structure of III are distorted octahedra. Based on structural data, the interaction between the coordinated Phen molecules of complexes I, [Ni(Phen)₂(iBu₂PS₂)](iBu₂PS₂) (II), and III is considered, as well as the packing modes of these complexes.     

Synthesis and characterization of glycol-modified vanadium(V) oxoisopropoxide and their oximato derivatives: sol–gel transformations of [VO(OPr i )3], [VO{OCH2CH2OCH2CH2O}{OPr i }] and [VO{OCH2CH2OCH2CH2O}{ON=C(CH3)(C4H3S-2)}] to vanadia

Reaction of [VO(OPr ⁱ )₃] (1) with [O(CH₂CH₂OH)₂] in 1:1 molar ratio in anhydrous benzene yield glycol-modified precursor, [VO{OCH₂CH₂OCH₂CH₂O}{OPr ⁱ }] (2). Further reactions of (2) with internally functionalized oximes in anhydrous benzene yield heteroleptic complexes of the type [VO{OCH₂CH₂OCH₂CH₂O}{ON=C(R)(Ar)}] (3–8) {where R=CH₃, Ar=C₄H₃O-2 (3), C₄H₃S-2 (4), C₅H₄N-2 (5); and when R=H, Ar=C₄H₃O-2 (6), C₄H₃S-2 (7), C₅H₄N-2 (8)}. All these derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic techniques. The crysoscopic molecular weight measurement as well as FAB mass study suggests dimeric nature of (2). However, FAB mass spectrum of (4), and the crysoscopic molecular weight measurements of (3), (4), (5) and (6) indicate the monomeric behavior of the oximato derivatives (3–8). Hexa-coordination around vanadium(V) has been proposed for both monomeric and dimeric derivatives. Sol–gel transformations of (1), (2) or (4) to vanadia [(a), (b) or (c), respectively] have been carried out at low sintering temperature (600 °C). The XRD patterns of (a), (b) or (c) indicate formation of a single orthorhombic phase in all the three cases. The SEM images suggest grain like [for (a) and (b)] and rod like [for (c)] morphology of the crystallites. IR, Raman spectra as well as EDX analyses indicate formation of pure vanadia. Absorption spectra of the vanadia (b) and (c) suggest energy band gaps of 2.53 and 2.65 eV, respectively.     

Triply bonded stannaacetylene (RC≡SnR): theoretical designs and characterization

The effect of substitution on the potential energy surfaces of RC≡SnR (R = F, H, OH, CH(3), SiH(3), Tbt, Ar*, SiMe(SitBu(3))(2), and SiiPrDis(2)) was explored using density functional theories (B3LYP/LANL2DZdp and B3PW91/Def2-QZVP). Our theoretical investigations indicate that all the triply bonded RC≡SnR molecules prefer to adopt a trans-bent geometry, which is in good agreement with the theoretical model (mode B). In addition, we demonstrate that the stabilities of the RC≡SnR compounds bearing smaller substituents (R = F, H, OH, CH(3), and SiH(3)) decrease in the order R(2)C═Sn: > RC≡SnR > :C═SnR(2). On the other hand, the triply bonded R'C≡SnR' molecules with bulkier substituents (R' = Tbt, Ar*, SiMe(SitBu(3))(2), and SiiPrDis(2)) were found to possess the global minimum on the singlet potential energy surface and are both kinetically and thermodynamically stable. Further, we used the B3LYP computations to predict the stability of stannaacetylene bearing the very bulky phosphine ligand. Our theoretical observations strongly suggest that both the electronic and the steric effects of bulky substituents play an important role in making triply bonded stannaacetylene (RC≡SnR) an intriguing synthetic target.     

Chemical bonding and properties in [Ni(N-heterocylic carbene)(NO)(R)] (R = H, Me, HC=CH2, and C≡CH) complexes: Theoretical insights

A series of N-heterocyclic carbene nickel complexes of the type [Ni(N-heterocylic carbene)(NO)(R)] (R = H, Me, HC=CH₂, and C≡CH) are examined to study the influence of a substituent on the molecular structure and bonding of these complexes. Geometrical and AIM analyses of the interaction between Ni and the carbene fragment reveal that for the metal-carbene bond donation is more important than back-donation. The NICS values suggest that aromaticity in the heterocyclic ring is less than in the free heterocycle.     

A single source precursor for low temperature processing of nanocrystalline MgAl2O4 spinel: synthesis and characterization of [MgAl2(μ3-O)(μ2-O(i)Pr)4(O(i)Pr)2]4

A novel polynuclear single-source precursor was prepared and characterized by single-crystal X-ray diffraction and multinuclear NMR spectroscopy. Nano-crystalline MgAl(2)O(4) spinel was synthesized via sol-gel processing of [MgAl(2)(μ(3)-O)(μ(2)-O(i)Pr)(4)(O(i)Pr)(2)](4). XRD, TGA-DSC and HRTEM confirmed the formation of a spinel phase at 475 °C, a temperature lower than any known processing temperature for MgAl(2)O(4).     

Energetics of the oxidative addition of I2 to [Ir(Μ-L)(CO)2]2 (L=S t Bu, 3,5-Me2pz,7-aza) complexes. X-ray structures of Ir(Μ-S t Bu)(I)(CO)2]2 and [Ir(Μ-3,5-Me2pz)(I)(CO)2]2

The energetics of the oxidative additive of I₂ to [Ir(-L)(CO)₂]₂ [L =t-buthylthiolate (S ^t Bu), 3,5-dimethylpyrazolate (3,5-Me₂pz), and 7-azaindolate (7-aza)] complexes was investigated by using the results of reaction-solution calorimetric measurements, X-ray structure determinations, and extended Hückel (EH) molecular orbital calculations. The addition of 1 mol of iodine to 1 mol of [Ir(-L)(CO)₂]₂, in toluene, leads to [Ir(-L)(I)(CO)₂]₂, with the formation of two Ir-I bonds and one Ir-Ir bond. The following enthalpies of reaction were obtained for this process: –125.8±4.9 kJ mol^–1 (L = S ^t Bu), –152.0±3.8 kJ mol^–1 (L=3,5-Me₂pz), and –205.9±9.9 kJ mol^⊃ (L=7-aza). These results are consistent with a possible decrease of the strain associated with the formation of three-, four-, and five-membered rings, respectively, in the corresponding products, as suggested by the results of EH calculations. The calculations also indicate a slightly stronger Ir-Ir bond for L = 3,5-Me₂pz than for L= S ^t Bu despite the fact that the Ir-Ir bond lengths are identical for both complexes. The reaction of 1 mol of [Ir(-S ^t Bu)(CO)₂]₂ with 2 mol of iodine to yield [Ir(-S ^t Bu)(I)₂(CO)₂]₂ was also studied. In this process four Ir-I bonds are formed, and from the corresponding enthalpy of reaction (–186.4±2.7 kJ mol^–1) a solution phase Ir-I mean bond dissociation enthalpy in [Ir(-S ^t Bu)(I)₂(CO)₂]₂, , was derived. This value is lower than most values reported for octahedral mononuclear Ir¹¹¹ complexes. New large-scale syntheses of the [Ir(-L)(CO)₂]₂ complexes, with yields up to 90%, using [Ir(acac)(CO)₂] as starting material, are also reported. The X-ray structures of [Ir(-L)(I)(CO)₂]₂ (L=S^tBu and 3,5-Me₂pz) complexes have been determined. For L=S^tBu the crystals are monoclinic, space group P2_l/c,a=10.741(2) å,b= 11.282(3) å,c=18.308(3) å,=96.71(1), andZ=4. Crystals of the-3,5-Me₂pz derivative are monoclinic, space group P2_l/n,a=14.002(3) å,b= 10.686(1) å,c=15.627(3) å,=112.406(8), andZ=4. In both complexes the overall structure can be described as two square-planar pyramids, one around each iridium atom, with the iodine atoms in the apical positions, and the equatorial positions occupied by two CO groups and the two sulfur atoms of the S ^t Bu ligands, or two N atoms of the pyrazolyl ligands. In the case of L=S^tBu the pyramids share a common edge defined by the two bridging sulfur atoms and for L =3,5-Me₂pz they are connected through the two N-N bonds of the pyrazolyl ligands. The complexes exhibit short Ir-Ir single bonds of 2.638(1) å for L=S^tBu and 2.637(1) å for L=3,5-Me₂Pz. The oxidative addition of iodine to [Ir(-3,5-Me₂pz)(CO)₂]₂ results in a remarkable compression of 0.608 å in the Ir-Ir separation.     

Study of allylic rearrangement in (μ-H)Os3(μ-O=CNRCH2CH=CH2)(CO)10 (R=H or CH3) clusters

The migration of the double bond in the allylcarboxamide ligands of (μ-H)Os₃(μ-O=CN RCH₂CH=CH₂) (CO)₁₀ (R=H (1) or CH₃ (2)), (μ-D)Os₃(μ-O=CNDCH₂CH=CH₂) (CO)₁₀, and (μ-H)Os₃(μ-O=CNHCD₂CH=CH₂)(CO)₁₀ clusters was studied by¹H,²H, and¹³C NMR spectroscopy. Neither μ-D nor ND groups in the deuterated complexes are directly involved in prototropic processes of allylic rearrangement. Initially, the deuterium atom of the CD₂ group migrates to the ψ-carbon atom of the allyl fragment to form the −CD=CH-CH₂D propenyl moiety, in which the deuterium and hydrogen atoms are gradually redistributed between the ψ-and β-carbon atoms. The triosmium cluster complexes containing the bridging carboxamide ligands O=CNRR' catalyze the allylic rearrangement ofN-allylacetamide. Based on the data obtained, the probable scheme of the allylic rearrangements in clusters1 and2 was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2182–2186, November, 1999.     

Cluster Complexes of Polythioether Macrocycles: The Synthesis and Molecular Structures of Ru6(CO)13(cis-SCH2 CHMe(CH2SCH2CHMe)2CH2)(μ6-C) and Ru6(CO)13(trans-SCH2 CHMe(CH2SCH2CHMe)2CH2)(μ6-C)

The reaction of a mixture of cis-3,7,11-trimethyl-1,5,9-trithiacyclododecane, cis-Me₃12S3, 1 and trans-3,7,11-trimethyl-l,5,9-trithiacyclododecane, trans-Me₃12S3, 2, with Ru₆(CO)₁₇(μ ₆-C), 3, yielded three new cluster compounds Ru₆(CO)₁₃(μ-η³-cis-SCH₂CHMe(CH₂SCH₂CHMe)₂CH₂)(μ ₆-C) 4, and two isomers of Ru₆(CO)₁₃(μ-η³-cis-SCH₂CHMe(CH₂SCH₂CHMe)₂CH₂)(μ ₆-C) 5a and 5b. The molecular structures of 4 and 5b were established by single crystal X-ray diffraction analyses. In both complexes, the macrocycles have adopted tridentate coordination with one of the sulfur atoms in a bridging position. Two carbonyl ligands occupy bridging positions in each compound. Crystal Data for 4·Me₂CO: space group=P2₁/n, a=11.295(1) Å, b=17.547(3) Å, c=20.318(3) Å, β=93.71(1)°, Z=4, 2900 reflections, R=0.025. Crystal Data for 5b·1.5 C₆H₆: space group=Pbca, a=31.8900(8) Å, b=23.4330(6) Å, c=21.6240(4) Å, Z=16, 12163 reflections, R=0.040.     

Carboxymethylcellulose (CMC)–hydroxyethylcellulose (HEC) based hydrogels: synthesis and characterization

A novel carboxymethylcellulose (CMC)–hydroxyethylcellulose (HEC)-based hydrogel with sensitivity to environmental changes, pH and salts was synthesized by using fumaric acid and malic acid at various concentrations. Water uptake capacity of hydrogels was investigated in distilled water, various salt and pH solutions. From pH-dependent studies, it was found that greater water uptake values were observed at greater pH values (7.4), and reversible pH responsiveness of CMC–HEC based hydrogels was obtained. Decreasing the water uptake capacity with increasing of the charge of the metal cation (Al³⁺ < Ca²⁺ < Na⁺) demonstrated metal ion responsiveness of CMC–HEC-based hydrogels. From tensile tests of the hydrogels, a greater crosslinker concentration led to greater tensile strength values. Thermogravimetric analysis and scanning electron microscopy images were used to determine the thermal stability and to observe morphological properties of the samples, respectively.     

Ruthenium(II) complexes of 2-(2′-pyridyl)naphthoimidazole: synthesis,characterization and DNA-binding studies

The perchlorate salts of two new ruthenium(II) complexes incorporating 2-(2′-pyridyl)naphthoimidazole are synthesized in good yield. Complexes [Ru(phen)₂(PYNI)]²⁺ (phen = 1,10-phenanthroline) 1 and [Ru(dmp)₂(PYNI)]²⁺ (dmp = 2,9-dimethyl-1,10-phenanthroline, PYNI = 2-(2′-pyridyl)naphthoimidazole) 2 are fully characterized by elemental analysis, FAB-MS, ES-MS, ¹H NMR and cyclic voltammetric methods. The DNA-binding behavior of the complexes have been studied by spectroscopic titration, viscosity measurements and thermal denaturation. Absorption titration and thermal denaturation studies reveal that these complexes are moderately strong binders of calf-thymus DNA (CT-DNA), with their binding constants spanning the range (2.73–5.35) × 10⁴ M^?1. The experimental results show that 1 interacts with calf thymus DNA (CT-DNA) by intercalative mode, while 2 binds to CT-DNA by partial intercalation.     

A tetranuclear tungsten carbido alkoxide cluster with a hydride ligand: W4(μ-C)(NMe)(OCH2Bu t )11(H)

A minor product in the reaction between W₂(NMe₂)₆ and neopentanol in hydrocarbon solvents has been isolated and characterized by elemental analysis,¹H and¹³C NMR spectroscopy and a single crystal X-ray study. At –174°C,a=11.669(1) Å,b=25.801(5) Å,c=24.345(4) Å, =100.91(1)°,Z=4,d _calcd=1.60 g cm^–3, and space group P2₁/c. The compound is formulated as W₄(₄-C)(NMe)(OCH₂Bu ^t )₁₁ (H). There is a W₄-butterfly and the carbido group is cradled between the wing-tip and back-bone W atoms with W-C=1.90–1.96 and 2.20–2.26 Å, respectively. The five W-W bonding distances span a narrow range 2.74–2.84 Å. The structure of this molecule resembles that previously reported for W₄(₄-C)(NMe)(OPr ⁱ )₁₂ where one OPr ⁱ ligand bonded to a backbone W atom is replaced by a hydride ligand. The hydride was not located crystallographically but is implicated by (i)a void at one W atom, (ii) itstrans-influence as determined by the W-O bond distance of the group trans to the void, and (iii) electron counting which requires the presence of a W₄(₄-C)¹⁴⁺ rather than a W₄(₄-C)¹³⁺ moiety in order to account for the observed diamagnetism. The present finding is compared with the previous preparations and characterizations of W₄(₄-C)¹⁴⁺ alkoxide supported clusters.     

[C5H4C(CH3)(C3H7)CH2CH=CH2]NdMg2(μ3-OH)(μ3-Cl)(μ2-Cl)3(THF)4Cl的合成和晶体结构分析

用Ｘ－射线衍射法测定了［Ｃ５Ｈ４Ｃ（ＣＨ３）（Ｃ３Ｈ７）ＣＨ２ＣＨ＝ ＣＨ２］ＮｄＭｇ２（μ３－ＯＨ）（μ３－Ｃｌ）（μ２－Ｃｌ）３（ＴＨＦ）４Ｃｌ的晶体结构。它属三斜晶系,空间群为Ｐ１－ ,ａ＝ １２．６９８（３）, ｂ＝ １３．６１６（３）, ｃ＝ １３．７１２（３）, α＝ ６８．９１（３）, β＝ ８４．３４（３）, γ＝ ６３．０７（３）°, Ｖ＝ １９６６（１）３, Ｍｒ＝ ８４９．７４, Ｄｘ＝ １．４１２ ｇ·ｃｍ － ３, μ＝ １．７２９７ ｍ ｍ － １, Ｆ（０００）＝ ８４０, Ｚ＝ ２, Ｒ＝ ０．０７３, ｗ Ｒ＝ ０．０８６（Ｉ≥３σ（Ｉ））。分子中Ｎｄ（Ⅲ）原子的配位数为八,形成一个严重扭曲的八面体结构。两个Ｍｇ 原子的配位情况相似,它们的配位数都是六,构成两个扭曲的八面体。这三个八面体通过三个共用平面联接     

Preparation and reactivity of metal-containing monomers 53. Synthesis and stability of a cluster monomer (μ-H)Os3(μ-OCNMe2)(CO)9PPh2CH2CH=CH2 in solution

The stability of the complex (μ-H)Os₃(μ-OCNMe₂)(CO)₉PPh₂CH₂CH=CH₂ (1), which contains a free unsaturated functional group in the terminal ligand PPh₂CH₂CH=CH₂, with respect to isomerization, chelation of the ligand, and other transformations in solutions was examined. No transformations of complex1 were observed in the course of synthesis from (μ-H)Os₃(μ-OCNMe₂)(CO)₉NMe₃ or upon heating in solution. Complex1 as well as complexes (μ-H)Os₃(μ-OCNMe₂)(CO)₉PHPh₂ and (μ-H)Os₃(μ-OCNMe₂)(CO)₉PPh₃, which were formed as admixtures, were isolated in the solid state and identified by¹H,¹H-{³¹P}, and¹H-{¹H} NMR, IR, and Raman spectroscopy and mass spectrometry. For Part 52, see Ref. 1. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1455–1460, August, 2000.     

Studies on binuclear complexes.: The synthesis and molecular structure of PdMo(μ-Ph2-Ppy)2(μ-CO)(CO)2 · 0.5CH2Cl2

Reaction of Mo(CO)₄(Ph₂Ppy)₂(Ph₂Ppy = 2-(diphenylphosphino)pyridine) with (1,5-cyclooctadiene)PdCl₂ gave PdMo(μ-Ph₂Ppy)₂(μ-CO)(CO)₂ · 0.5 CH₂Cl₂. The molecular structure was determined by X-ray diffraction. The complex crystallized in the monoclinic space group P2₁/c with a 14.615(2), b 15.358(3), c 17.721(2) Å, β = 97.18(1)°, Z = 4. The final R = 0.055 and R_w = 0.065 values were for independent reflections. The structure of the binuclear complex indicates that it possesses a PdMo bond which has a bond length of 2.817(1) Å. The palladium atom is five-coordinated and the molybdenum atom is seven-coordinated. Both metal atoms possess the formal oxidation state +1. The molecule is chiral and belongs to the C₁ point group. Different types of spectra are also discussed.     

Preparation and structural characterization of the isomorphous compounds: [Bu4N][Mo3(μ3-O)(μ-X)3(μ-OAc)3 X 3]·(CH3)2CO,X=Cl,Br

The reaction of MoCl₃(H₂O)₃ with a mixture of acetic acid and acetic anhydride in the presence of [N(C₄H₉)₄][BF₄] followed by crystallization from acetone/hexane gives a 77% yield of dark purple [NBu₄][Mo₃OCl₆(OAc)₃]·Me₂CO (1). A similar reaction employing MoBr₃(H₂O)₃ gives purple [NBu₄][Mo₃OBr₆(OAc)₃]·Me₂CO (2) in 50% yield. Also produced in this reaction in low (10–20%) yields are [NBu₄]₂[Mo₄OBr₁₂] · 0.5Me₂CO and [NBu₄]₂[Mo₃OBr₆(OAc)₃] · Me₂CO which will be discussed elsewhere Compounds (1) and (2) are isomorphous, space groupP2₁/n,Z=4 with the following unit cell dimensions, where the values for (1) and (2) are given in that order for each one:a=13.406(4), 13.726(5) Å;b=15.701(4), 15.839(5) Å;c=19.250(5), 19.831(6) Å; =101.61(2), 102.92(3)°. Both (1) and (2) are eight-electron species in which the mean Mo-Mo distances are 2.578(1) Å and 2.597(1) Å, respectively.