Deuterium isotope effect on the atomic alignment dependence in the reaction of oriented Ar (3P2) with (CH3CN)2 and (CD3CN)2 dimers

The effect of atomic alignment on CN (B2Sigma+) formation has been studied in the reaction of oriented Ar (3P2) with (CX3CN)2 (X = H, D). The reaction cross-section for each magnetic M'(J) substate in the collision frame sigma|M'(J)|(H(D),d) relative to the cross-section sigma0(H,m) in the CH(3)CN reaction was determined to be sigma0(H,d)/sigma|1|(H,d)/sigma|2|(H,d)/sigma0(D,d)/sigma|1|(D,d):/sigma|2|(D,d)= 0.87/1.00/0.98/1.58/1.93/1.78. A notable deuterium isotope effect was observed. In contrast with the monomer reactions, a significant decrease of sigma0(H(D),d) relative to the other cross-sections of sigma|M'(J)|(H(D),d) was observed.     

Steric effect in the energy transfer reaction of Ar(3P2)+N2

Steric effect for N2(C,3Piu) formation in the energy transfer reaction of Ar(3P2)+N2 was directly measured by using an oriented Ar(3P2,MJ=2) beam at a collision energy of 0.06 eV. The N2(C,3Piu) chemiluminescence intensity was measured as a function of the magnetic orientation field direction in the collision frame. A significant alignment effect on the energy transfer probability was observed. The relative reactivity for each magnetic substate in the collision frame sigma|MJ'|was determined to be sigma|2|:sigma|1|:sigma(0)=0.50:0.60:1.00. It is suggested that the observed steric effect is primarily due to the favorable configuration of the 3p orbital for the efficient overlap with the 2sigma(u) molecular orbital of N(2).     

Reaction dynamics on the formation of 1- and 3-cyanopropylene in the crossed beams reaction of ground-state cyano radicals (CN) with propylene (C3H6) and its deuterated isotopologues

Crossed molecular beams experiments were utilized to explore the chemical reaction dynamics of ground-state cyano radicals, CN(X(2)Sigma(+)), with propylene (CH3CHCH2) together with two d3-isotopologues (CD3CHCH2, CH3CDCD2) as potential pathways to form organic nitriles under single collision conditions in the atmosphere of Saturn's moon Titan and in the interstellar medium. On the basis of the center-of-mass translational and angular distributions, the reaction dynamics were deduced to be indirect and commenced via an addition of the electrophilic cyano radical with its radical center to the alpha-carbon atom of the propylene molecule yielding a doublet radical intermediate: CH3CHCH2CN. Crossed beam experiments with propylene-1,1,2-d3 (CH3CDCD2) and propylene-3,3,3-d3 (CD3CHCH2) indicated that the reaction intermediates CH3CDCD2CN (from propylene-1,1,2-d3) and CD3CHCH2CN (from propylene-3,3,3-d3) eject both atomic hydrogen through tight exit transition states located about 40-50 kJ mol(-1) above the separated products: 3-butenenitrile [H2CCDCD2CN] (25%), and cis/trans-2-butenenitrile [CD3CHCHCN] (75%), respectively, plus atomic hydrogen. Applications of our results to the chemical processing of cold molecular clouds like TMC-1 and OMC-1 are also presented.     

Steric effects in electron transfer from potassium to pi-bonded oriented molecules CH3CN, CH3NC, and CCl3CN

Electron transfer from K atoms to oriented CH3CN, CH3NC, and CCl3CN is studied in crossed beams at energies near the threshold for forming an ion pair. For the methyl compounds, the dominant ions are K+ and CN-; the steric asymmetry is very small and energy-independent, characteristic of sideways attack with the electron apparently entering the pi*CN antibonding orbital. Migration of the electron to the sigma*CC orbital to break the C-C bond is greatly facilitated by interaction with the atomic donor. CH2CN- is formed in collisions preferring CH3-end attack, and the steric asymmetry becomes very large near threshold. CCl3CN mostly forms Cl- in collisions slightly favoring the CCl3 end with a small energy dependence with the electron apparently entering the sigma* LUMO. CN- is formed in much smaller yield with a slight preference for the CN end. The parent negative ion CCl3CN- is observed, and a lower limit for its electron affinity is estimated to be 0.3 eV. Fragment ions CCl2CN- and CClCN- are also observed with upper limits for the quantity bond dissociation energy - electron affinity (BDE - EA) estimated to be 0.6 and 1.0 eV, respectively.     

The Jahn-Teller effect in CH(3)CN(+) (X(2)E) and CD(3)CN(+) (X(2)E) studied by zero kinetic energy photoelectron spectroscopy

The Jahn-Teller effect in CH(3)CN(+) (X(2)E) and CD(3)CN(+) (X(2)E) has been found experimentally by zero kinetic energy (ZEKE) photoelectron spectroscopy using coherent extreme ultraviolet (XUV) radiation. The vibronic bands of CH(3)CN(+) (X(2)E) and CD(3)CN(+) (X(2)E) at about 4500 cm(-1) above the ground states have been recorded. The spectra consist mainly of the Jahn-Teller active C-C[triple bond]N bending (v(8)), the CN stretching (v(2)), the CH(3) (CD(3)) deforming (v(6)), and the C-C stretching (v(4)) vibronic excitations. The Jahn-Teller active vibronic bands (v(8)) have been assigned with a harmonic model including linear and quadratic Jahn-Teller coupling terms, taking into account only the single mode vibronic excitation. The ionization potentials of CH(3)CN and CD(3)CN have also been determined, and their values are 12.2040(+/-0.001) and 12.2286(+/-0.001) eV, respectively.     

Ab initio study of the spectroscopy of (CH3)(3)CN and (CH3)(2)CHN

Using the complete active space self-consistent field (CASSCF) method with 6-311++g(3df,3pd) basis sets, a few electronic states of nitrenes (CH3)3CN and (CH3)2CHN and their positive ions are calculated. All calculated states are valence states, and their characteristics are discussed in detail. In order to investigate the Jahn-Teller effect on (CH3)3CN radical, Cs symmetry was used for (CH3)3CN and (CH3)2CHN in the calculations. The results of our calculations (CASPT2 adiabatic excitation energies and RASSI oscillator strengths) suggest that the calculated transitions of (CH3)3CN at 27,710 cm(-1) and (CH3)2CHN at 28,110 cm(-1) are attributed to 23A' --> 13A', while those of (CH3)3CN at 28,916 cm(-1) and (CH3)2CHN at 29,316 cm(-1) are attributed to 13A' --> 13A'. The vertical and adiabatic ionization energies were obtained to compare with the photoelectron spectroscopic data. These results are in agreement with previous experimental data. Also, we present a comprehensive review on the CAS calculation results for (CH3)nCH(3-n)N (n = 0-3) presented in our previous and present papers.     

Intra- and intermolecular vibrational energy transfer in tungsten carbonyl complexes W(CO)5(X) (X=CO, CS, CH3CN, and CD3CN)

Vibrational energy relaxation of degenerate CO stretches of four tungsten carbonyl complexes, W(CO)6, W(CO)5(CS), W(CO)5(CH3CN), and W(CO)5(CD3CN), is observed in nine alkane solutions by subpicosecond time-resolved infrared (IR) pump-probe spectroscopy. Between 0 and 10 ps after the vibrational excitation, the bleaching signal of the ground-state IR absorption band shows anisotropy. Decay of the anisotropic component corresponds either to the rotational diffusion of the molecule or to the intramolecular vibrational energy transfer among the degenerate CO stretch modes. The time constant of the anisotropy decay, tauaniso, shows distinct solvent dependence. By comparing the results for the T1u CO stretch of W(CO)6 and the A1 CO stretch of W(CO)5(CS), the time constant of the rotational diffusion, taur, and the time constant of the intramolecular energy transfer among the three degenerate vibrational modes, taue, are determined as 12 and 8 ps, respectively. The tauaniso value increases as the number of carbon atoms in the alkane solvent increases. After 10 ps, the recovery of the bleaching becomes isotropic. The isotropic decay represents the vibrational population relaxation, from v=1 to v=0. In heptane, the time constant for the isotropic decay, tau1, for W(CO)5(CS) and W(CO)6 was 140 ps. The tau1 for the two acetonitrile-substituted complexes, however, shows a smaller value of 80 ps. The vibrational energy relaxation of W(CO)5(CH3CN) and W(CO)5(CD3CN) is accelerated by the intramolecular energy redistribution from the CO ligand to the acetonitrile ligand. In the nine alkane solutions, the tau1 value of W(CO)6 ranges between 124 and 158 ps, showing the apparent V-shaped solvent dependence with its minimum in decane, while the tau1 value shows little solvent dependence for W(CO)5(CH3CN) and W(CO)5(CD3CN).     

Vibrational relaxation of CN stretch of pseudo-halide anions (OCN-, SCN-, and SeCN-) in polar solvents

The vibrational relaxation dynamics of pseudo-halide anions XCN- (X = O, S, Se) in polar solvents were studied to understand the effect of charge on solute-to-solvent intermolecular energy transfer (IET) and solvent assisted intramolecular vibrational relaxation (IVR) pathways. The T1 relaxation times of the CN stretch in these anions were measured by IR pump/IR probe spectroscopy, in which the 0-1 transition was excited, and the 0-1 and 1-2 transitions were monitored to follow the recovery of the ground state and decay of the excited state. For these anions in five solvents, H2O, D2O, CH3OH, CH3CN, and (CH3)2SO, relaxation rates followed the trend of OCN- > SCN- > SeCN-. For these anions and isotopes of SCN-, the relaxation rate was a factor of a few (2.5-10) higher in H2O than in D2O. To further probe the solvent isotope effect, the relaxation rates of S12C14N-, S13C14N-, and S12C15N- in deuterated methanols (CH3OH, CH3OD, CH3OH, CD3OD) were compared. Relaxation rate was found to be affected by the change of solvent vibrational band at the CN- stretching mode (CD3 symmetric stretch) and lower frequency regions, suggesting the presence of both direct IET and solvent assisted IVR relaxation pathways. The possible relaxation pathways and mechanisms for the observed trends in solute and solvent dependence were discussed.     

State-resolved dynamics of the CN(B2Sigma+) and CH(A2Delta) excited products resulting from the VUV photodissociation of CH3CN

Fourier transform visible spectroscopy, in conjunction with VUV photons produced by a synchrotron, is employed to investigate the photodissociation of CH3CN. Emission is observed from both the CN(B2Sigma+-X2Sigma+) and CH(A2Delta-X2Pi) transitions; only the former is observed in spectra recorded at 10.2 and 11.5 eV, whereas both are detected in the 16 eV spectrum. The rotational and vibrational temperatures of both the CN(B2Sigma+) and CH(A2Delta) radical products are derived using a combination of spectral simulations and Boltzmann plots. The CN(B2Sigma+) fragment displays a bimodal rotational distribution in all cases. Trot(CN(B2Sigma+)) ranges from 375 to 600 K at lower K' and from 1840 to 7700 K at higher K' depending on the photon energy used. Surprisal analyses indicate clear bimodal rotational distributions, suggesting CN(B2Sigma+) is formed via either linear or bent transition states, respectively, depending on the extent of rotational excitation in this fragment. CH(A2Delta) has a single rotational distribution when produced at 16 eV, which results in Trot(CH(A2Delta))=4895+/-140 K in v'=0 and 2590+/-110 K in v'=1. From thermodynamic calculations, it is evident that CH(A2Delta) is produced along with CN(X2Sigma+)+H2. These products can be formed by a two step mechanism (via excited CH3* and ground state CN(X2Sigma+)) or a process similar to the "roaming" atom mechanism; the data obtained here are insufficient to definitively conclude whether either pathway occurs. A comparison of the CH(A2Delta) and CN(B2Sigma+) rotational distributions produced by 16 eV photons allows the ratio between the two excited fragments at this energy to be determined. An expression that considers the rovibrational populations of both band systems results in a CH(A2Delta):CN(B2Sigma+) ratio of (1.2+/-0.1):1 at 16 eV, thereby indicating that production of CH(A2Delta) is significant at 16 eV.     

Direct Lanthanide-Transition Metal Interactions: Synthesis of (NH(3))(2)YbFe(CO)(4) and Crystal Structures of {[(CH(3)CN)(3)YbFe(CO)(4)](2).CH(3)CN}(infinity) and [(CH(3)CN)(3)YbFe(CO)(4)](infinity)

The heterometallic complex (NH(3))(2)YbFe(CO)(4) was prepared from the reduction of Fe(3)(CO)(12) by Yb in liquid ammonia. Ammonia was displaced from (NH(3))(2)YbFe(CO)(4) by acetonitrile in acetonitrile solution, and the crystalline compounds {[(CH(3)CN)(3)YbFe(CO)(4))](2).CH(3)CN}(infinity) and [(CH(3)CN)(3)YbFe(CO)(4)](infinity) were obtained. An earlier X-ray study of {[(CH(3)CN)(3)YbFe(CO)(4)](2).CH(3)CN}(infinity) showed that it is a ladder polymer with direct Yb-Fe bonds. In the present study, an X-ray crystal structure analysis also showed that [(CH(3)CN)(3)YbFe(CO)(4)](infinity) is a sheetlike array with direct Yb-Fe bonds. Crystal data for {[(CH(3)CN)(3)YbFe(CO)(4)](2).CH(3)CN}(infinity): monoclinic space group P2(1)/c, a = 21.515(8) ?, b = 7.838(2) ?, c = 19.866(6) ?, beta = 105.47(2) degrees, Z = 4. Crystal data for [(CH(3)CN)(3)YbFe(CO)(4)](infinity): monoclinic space group P2(1)/n, a = 8.364(3) ?, b = 9.605(5) ?, c = 17.240(6) ?, beta = 92.22(3) degrees, Z = 4. Electrical conductivity measurements in acetonitrile show that these acetonitrile complexes are partially dissociated into ionic species. IR and NMR spectra of the solutions reveal the presence of [HFe(CO)(4)](-). However, upon recrystallization, the acetonitrile complexes show no evidence for the presence of [HFe(CO)(4)](-) on the basis of their IR spectra. The solid state MAS (2)H NMR spectra of deuterated acetonitrile complexes give no evidence for [(2)HFe(CO)(4)](-). It appears that rupture of the Yb-Fe bond could occur in solution to generate the ion pair [L(n)Yb](2+)[Fe(CO)(4)](2-), but then the highly basic [Fe(CO)(4)](2-) anion could abstract a proton from a coordinated acetonitrile ligand to form [HFe(CO)(4)](-). However, upon crystallization, the proton could be transferred back to the ligand, which results in the neutral polymeric species.     

Synthesis and Crystal Structure of［Lu（NO_3）_3（H_2O）_2（CH_3CN）］（Benzo－15－C－5）·CH_3CN

ＳｙｎｔｈｅｓｉｓａｎｄＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆ［Ｌｕ（ＮＯ_３）_３（Ｈ_２Ｏ）_２（ＣＨ_３ＣＮ）］（Ｂｅｎｚｏ－１５－Ｃ－５）·ＣＨ_３ＣＮＷａｎｇＲｕｉ－Ｙａｏ；ＪｉｎＺｈｏｎｇ－Ｓｈｅｎｇ；ＮｉＪｉａ－Ｚｕａｎ（Ｌａｂｏｒａｔｏｒｙｏ...     

Synthesis, structure, and magnetic properties of [(CH3CN)5V-O-V(CH3CN)5][BF4]4

The reaction of vanadium(III) acetylacetonate with HBF4 in acetonitrile yields [(CH3CN)5V-O-V(CH3CN)5][BF4]4, a material that serves as a convenient precursor to other [V-O-V]4+ species such as [(bipy)2(CH3CN)V-O-V(CH3CN)(bipy)2][BF4]4 (bipy=2,2'-bipyridine). Single-crystal X-ray diffraction shows that the V-O-V linkage of [(CH3CN)5V-O-V(CH3CN)5]4+ is linear. An Evans method measurement of the solution-phase magnetic susceptibility indicates strong ferromagnetic coupling between the vanadium centers. Magnetic susceptibility (chi) and magnetization (M(H)) data for a powdered sample and for a single crystal oriented with its V-O-V axis parallel to the applied field were measured over 1.8-300 K. The results suggest that the V(III) centers are ferromagnetically coupled with J approximately 72 K (approximately 50 cm(-1)) yielding a ground state with a total spin Stotal=2. Theoretical fit to the M(H) plot for the single crystal yielded g||=2.01+/-0.01 and the zero-field splitting parameter D=0.60+/-0.04 K (0.42+/-0.03 cm(-1)). EPR measurements at 34 and 101.6 GHz are consistent with the Stotal=2 ground state and yield g||=1.9825, g perpendicular=1.9725 and D=0.57+/-0.03 K.     

Development of a cooled He*(23S) beam source for measurements of state-resolved collision energy dependence of Penning ionization cross sections: Evidence for a stereospecific attractive well around methyl group in CH3CN

A low-temperature discharge nozzle source with a liquid-N(2) circulator for He*(2(3)S) metastable atoms has been developed in order to obtain the state-resolved collision energy dependence of Penning ionization cross sections in a low collision energy range from 20 to 80 meV. By controlling the discharge condition, we have made it possible to measure the collision energy dependence of partial ionization cross sections (CEDPICS) for a well-studied system of CH(3)CN+He*(2(3)S) in a wide energy range from 20 to 350 meV. The anisotropic interaction potential energy surface for the present system was obtained starting from an ab initio model potential via an optimization procedure based on classical trajectory calculations for the observed CEDPICS. A dominant attractive well depth was found to be 423 meV (ca. 10 kcal/mol) at a distance of 3.20 A from the center of mass of CH(3)CN in the N-atom side along the CCN axis. In addition, a weak attractive well (ca. 0.9 kcal/mol) surrounding the methyl group (-CH(3)) has been found and ascribed to the interaction between an unoccupied molecular orbital of CH(3)CN and 2s atomic orbital of He*(2(3)S).     

Delta(DeltaS) and Delta(DeltaS) for the competing bond cleavage reactions in (CH3CN)(ROH)H+ [R = CH3, C2H5, C3H7, (CH3)2CH

Microcanonical variational transition-state theory was used to determine the entropies of activation for hydrogen-bond cleavage reactions leading to CH(3)CN + ROH(2)(+) in a series of acetonitrile-alcohol proton-bound pairs (CH(3)CN)(ROH)H(+) (where R = CH(3), CH(3)CH(2), CH(3)CH(2)CH(2), and (CH(3))(2)CH). In each case, the dissociation potential surface was modelled at the MP2/6-31 + G(d) level of theory. The dissociating configurations having the minimum sums-of-states were identified in each case and the resulting entropies of activation were calculated. Combined with previous work on the competing reaction leading to CH(3)CNH(+) + ROH, the results permitted the determination of the Delta(DeltaS) in each proton-bound pair. For the (CH(3)CN)(CH(3)OH)H(+) and (CH(3)CN)(CH(3)CH(2)OH)H(+) proton-bound pairs, the entropies of activation for the two dissociating channels are essentially the same [i.e., Delta(DeltaS) = 0], while Delta(DeltaS) for the propanol-containing pairs ranged between 40 and 45 J K(-1) mol(-1). The latter non-zero values are due to a combination of the location of the dividing surface in each dissociation and the rapidity with the frequencies of the vanishing vibrational modes go to zero as they are converted to product translations and rotations during the dissociation.     

Effect of molecular rotation on the atomic alignment dependence in the oriented Ar (3P2) + CF3H reaction

Atomic alignment effect for the CF3* formation in the oriented Ar (3P2, MJ = 2) + CF3H reaction has been investigated at different two CF3H beam conditions: effusive and supersonic beams. The chemiluminescence intensity of CF3* was measured as a function of the magnetic orientation field direction in the collision frame. A significant contribution of rank 4 moment was recognized. The cross-section for each magnetic M'(J) substate in the collision frame, sigma|M'(J)|, was determined to be sigma(|M'(J)|=0):sigma(|M'(J)|=1):sigma(|M'(J)|=2) = 1.00:0.84 +/- 0.02:0.88 +/- 0.02 for the effusive CF3H beam condition. The atomic alignment effect was found to significantly depend on the CF3H beam condition. For the supersonic beam condition, sigma(|M'(J)|=0&1) was changed to be smaller than sigma(|M'(J)|=2).     

水对二氧化碳插入TpRu(PPh3)(CH3CN)H生成甲酸根配合物的影响

分别研究了在干燥THF及H2O/THF条件下CO2与TpRu(PPh3)(CH3CN)H(Tp=Hydrotris(pyrazolyl)borate)的反应, 发现水对CO2插入TpRu(PPh3)(CH3CN)H的反应具有显著促进作用. 原位高压NMR研究显示, 在水存在下, CO2插入Ru-H键形成水合甲酸根配合物TpRu(PPh3)(CH3CN)(η1-OCHO)H2O, 其中甲酸根配体与溶剂中水分子形成分子间氢键. B3LYP水平的理论计算表明, CO2插入TpRu(PPh3)(CH3CN)H 中Ru-H键的能垒由于水的存在而显著降低; 在过渡态, CO2分子中碳原子的亲电性由于其氧原子与水分子形成氢键而得到增强. TpRu(PPh3)(CH3CN)(η1-OCHO)*H2O很快转化为另一甲酸根配合物TpRu(PPh3)(H2O)(η1-OCHO), 并与之达成平衡. 后者由于甲酸根配体与水分子配体间形成分子内氢键而稳定.     

[Mo2FeS8O2][Et4N]3CH3CN原子簇化合物的晶体结构

[Mo_2FeS_8O_2][Et_4N]_3·CH_3CN晶体属三斜晶系,PI空间群.α=9.998(1)A,b=13.868(3)A,c=16.796(3)A,α=74.66(2)°,β=85.41(1)°,ν=72.21(1)°,Ζ=2.结构参数经块矩阵最小二乘法精修后,最后的偏离因子R=0.037,R_w=0.034.平均键长Mo—Fe为2.722A,Mo—S为2.358A,Fe—S为2.244A,Mo—O为1.697A.结果表明:标题化合物是一个结构新颖的原子簇化合物.它是由一个三价原子簇阴离子与三个一价的乙基季铵阳离子靠静电引力结合在一起,又溶剂合一个乙氰分子的原子簇化合物而形成.     

Symmetry-breaking substitutions of [Re(CN)8]3- into the centered, face-capped octahedral clusters (CH3OH)24M9M'6(CN)48 (M = Mn, Co; M = Mo, W)

The diamagnetic complex [Re(CN)8]3- is shown to react with Mn2+ ions in methanol to generate the centered, face-capped octahedral cluster (CH3OH)24Mn9Re6(CN)48, which is structurally analogous to (CH3OH)24Mn9Mo6(CN)48. Related reactions involving stoichiometric mixtures of octacyanometalate complexes generate the substituted species (CH3OH)24Mn9Mo5Re(CN)48, (CH3OH)24Co9Mo5Re(CN)48, (CH3OH)24Mn9Mo3Re3(CN)48, (CH3OH)24Mn9W5Re(CN)48 and (CH3OH)24Co9W5Re(CN)48, in which the O(h) symmetry of the cluster core is broken. Reassessment of the magnetic properties of the Mn9Mo6(CN)48 cluster confirm that it possesses a ground state spin of S = 39/2, but does not exhibit single-molecule-magnet behavior. Lowering the symmetry of the molecule by substitutions of ReV at one or three of the MoV sites does not lead to an overall increase in the magnetic anisotropy, as probed by ac magnetic susceptibility measurements. A similar result occurs for the other substituted species, with the important exception of the new single-molecule magnet (CH3OH)24Co9W5Re(CN)48, for which the spin reversal barrier is significantly reduced relative to that observed previously in (CH3OH)24Co9W6(CN)48.     

A study of structural and bonding variations in the homologous series [Mo(2)(CN)(6)(dppm)(2)](n-) (n = 2, 1, 0)

Reaction of Mo(2)Cl(4)(dppm)(2) (dppm = bis(diphenylphosphino)methane) with 6 equiv of [n-Bu(4)N][CN] or [Et(4)N][CN] in dichloromethane yields [n-Bu(4)N](2)[Mo(2)(CN)(6)(dppm)(2)] (1) and [Et(4)N](2)[Mo(2)(CN)(6)(dppm)(2)] (2), respectively. The corresponding one- and two-electron oxidation products [n-Bu(4)N][Mo(2)(CN)(6)(dppm)(2)] (3) and Mo(2)(CN)(6)(dppm)(2) (4)were prepared by reactions of 1 with the oxidant NOBF(4). Single-crystal X-ray structures of 2.2CH(3)CN, 3.2CH(3)CN.2H(2)O, and 4.2CH(3)NO(2) were performed, and the results confirmed that all three complexes contain identical ligand sets with trans dppm ligands bisecting the Mo(2)(mu-CN)(2)(CN)(4) equatorial plane. The binding of the bridging cyanide ligands is affected by the oxidation state of the dimolybdenum core as evidenced by an increase in side-on pi-bonding overlap of the mu-CN in going from 1 to 4. The greater extent of pi-donation into Mo orbitals is accompanied by a lengthening of the Mo-Mo distance (2.736(1) A in Mo(2)(II,II) (2), 2.830(1) A in Mo(2)(II,III) (3), and 2.936(1) A in Mo(2)(III,III) (4)). A computational study of the closed-shell members of this homologous series, [Mo(2)(CN)(6)(dppm)(2)](n)() (n = 2-, 0), indicates that the more pronounced side-on pi-donation evident in the X-ray structure of 4 leads to significant destabilization of the delta orbital and marginal stabilization of the delta() orbitals with respect to nearly degenerate delta and delta orbitals in the parent compound, 2. The loss of delta contributions combined with the reduced orbital overlap due to higher charges on molybdenum centers in oxidized complexes 3 and 4 is responsible for the observed increase in the length of the Mo-Mo bond.     

31~P NMR Studies on Quasi-Aromaticity of Mo_3S_3 Core and Structure of {Mo_3(μ_3-S)_3[μ-SOP(OEt)_2][S_2P(OEt)_2]_3(CH3CN)}*CH_3CN

1INTRoDUCTIoNDuringthisdecade,extensivestudieshavebeendoneontheclustercompoundswithMosS`coret1}.Wehavedevelopedanewmethodtosynthesizeaseriesof[Mo,o.S'-.J' ,n=O,l,2,3,inaqueoussolution(2).BythereactionofaqueousclusterionswithHdtp,weobtainedtheircorrespondingcompoundswhichwerefirst-lysynthesizedbythespontaneousself-assemblymethod.Theseaqueousclusterionsandtheirderivativescoordinatedbyorganicligands,bothinaqueousphaseandnon-aqueoussolution,demonstratedreactiveactivitiestowardsmanytransitio…