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1.
Vapour pressure measurements have been carried out on the complexes W(CO)it6-x (NCCH3x(x=1,2,3) and Mo(CO)it6-x(NCCH3x(x=1,3) employing the Knudsen effusion technique. The following enthalpies of sublimation, ΔH298sub(kJ mole?1), have been determined from vapour pressure data: W(CO)5(NCCH3)=98.1±2.0; W(CO) 4 (NCCH3)2=131.0±6.0; W(CO)3(NCCH33=103.4±6.0; Mo(CO)5(NCCH3)=105.8± 5.6; and Mo(CO)3(NCCH3)3=111.3±3.0.  相似文献   

2.
Acetato-bis(pyrazole) complexes [Mo(η3-methallyl)(O2CMe)(CO)2(pz∗H)2], (methallyl = CH2C(CH3)CH2) and fac-[M(O2CMe)(CO)3(pz∗H)2], (pz∗H = pyrazole or 3,5-dimethylpyrazole, dmpzH; M = Mn, Re) are obtained from [Mo(η3-methallyl)Cl(CO)2(NCMe)2] or fac-[MBr(CO)3(NCMe)2] [M = Mn (synthesized in situ), Re], 2 equiv. of pyrazole, and 1 equiv. of sodium acetate for Mo complexes, or silver acetate for Mn or Re complexes. The chlorido-complexes [Mo(η3-methallyl)Cl(CO)2L2] (L = pzH, dmpzH), obtained from the same starting material by substitution of MeCN by pzH or dmpzH, are also described. The crystal structures of the fac-acetato-bis(dimethylpyrazole) complexes present the same pattern of intramolecular hydrogen bonds between the acetate and the dimetylpyrazole ligands, whereas the crystal structures of the fac-acetato-bis(pyrazole) complexes show different hydrogen bonds patterns, with intermolecular interactions. NMR data indicate that these interactions are not maintained in solution.  相似文献   

3.
The reactions of the substituted Group VI metal carbonyls of the type M(CO)4(2-Mepy)2 (M = Mo, w) and M(CO)3(L)3 (L = py, M = Mo, W; L = NH3, M = Mo) with mercuric derivatives HgX2 (X = Cl, CN, SCN) have given rise to three series of tricarbonyl complexes: M(CO)3(py)HgCl2 · 1/2HgCl2 (M = Mo, W); 2[M(CO)3(L)]Hg(CN)·nHg(CN)x (L = py, M = Mo, W, n = 12, × = 2; L = 2- Mepy, × = 1; M = Mo, n = 3; M = W, n = 1); and [M(CO)3(L)Hg(SCN)2 · nHg(SCN)2] (L = py, M = Mo,W, n = 0; L = 2-Mepy, M = Mo, W, n = 12; L = NH3, M = Mo, n = 0) depending on which mercuric compound is employed. All the reactions with Hg(SCN)2 give isolable products whereas those with Hg(CN)2 and HgCl2 did so far only the reactions with [M(CO)4(2-Mepy)2] and M(CO)3(py)3. The greater reactivity of Hg(SCN)2 than of Hg(CN)2 and HgCl2 is consistent with the various acceptor capacities of the groups bonded to the mercury atom.The reactions studied always involve displacement of the N-donor ligand of the original complex and partial or total displacement of the halide or pseudohalide groups of the mercury compound to give in all cases compounds containing MHg bonds. In addition, elimination of a CO group in the tetracarbonyl complexes M(CO)4(2-Mepy)2occurs.  相似文献   

4.
Reaction of fac-[Mn(CO)3(S2CPR3)(Br)] with [Mo(CO)3(NCMe)3] produces a member of a novel class of heterodinuclear complex [MnMo(CO)6(μ-Br)(μ-S2CPR3)] (R = Cy, iPr), which contains S2CPR3 bridging ligands, acting as an (κ-S,S′) chelate towards Mn, and as an (κ-S,C,S′) pseudoallyl group to Mo, without a direct MoMn bond. One carbonyl group in [MnMo(CO)6(μ-Br)(μ-S2CPR3)] can be easily displaced at room temperature by neutral ligands such as PEt3 and P(OMe)3, affording pentacarbonyl complexes, [MnMo(CO)5(L)(μ-Br)(μ-S2CPR3].  相似文献   

5.
Reaction between cis-[Mo(CO)2(dmpe)2] (dmpe =Me2PCH2CH2PMe2) and organic π-acids tetracyanoethene (TCNE), 1,2,4,5-tetracyanobenzene (TCNB) and 1,3,5-trinitrobenzene (TNB) proceeds via electron transfer from the metal complex, which is oxidised to the 17-electron trans-[Mo(CO)2(dmpe)2]+ ion, to the organic acceptor which is reduced to the radical anion. The final products of the reactions are characterised ascis-[Mo{C2(CN)3} (CO)2(dmpe)2] [CN], cis-[Mo{C6H2(CN)4} (CO)2(dmpe)2] [C6H2(CN)4]8 and [Mo(CO)2(dmpe)2 · 2 C6H3(NO2)3] by analysis and spectroscopic (IR, NMR, ESR) measurements which are compared with those of cis-[MoX(CO)2(dmpe)2]X (X = Cl, Br, I) and fac, fac-[Mo2Cl4(CO)4(dmpe)3]. The reaction of cis-[Cr(CO)2(dmpe)2] with TCNE gives trans-[Cr(CO)2(dmpe)2]+ [TCNE]? only.  相似文献   

6.
The complexes [MI2(CO)3(NCMe)2] (M = Mo or W) react with one equivalent of L in CH2Cl2 at room temperature to give initially the mononuclear seven-coordinate complexes [MI2(CO)3(NCMe)L] which have been isolated for M = W; L = 3Cl-py, 3Br-py, 4Cl-py and 4Br-py. These compounds dimerise to give the iodidebridged dimers [M(μ-I)I(CO)3L]2 by displacement of acetonitrile. When M = Mo; L = 3Cl-py, 3Br-py, 4Cl-py and 4Br-py, and when M = Mo and W; L = py, 2Me-py (for M = W only), 4Me-py, 3,5-Me2-py, 2Cl-py and 2Br-py, only the dimeric complexes have been isolated. The ease of dimerisation of [MI2(CO)3(NCMe)L] is discussed in terms of the steric and electronic effects of the substituted pyridines.  相似文献   

7.
Reactions between [Mn(CO)5Br] and dpkbh in low boiling solvents in air gave fac-[MnI(CO)3(κ2-Npy,Nim-dpkbh)Br]·H2O, [MnIIBr2(κ3-Npy,Nim,O-dpkbh)], and [MnII(κ3-Npy,Nim,O-dpkbh-H)2]·0.5H2O (Nim = imine nitrogen and Npy = pyridyl nitrogen). Crystallization of fac-[MnI(CO)3(κ2-Npy,Nim-dpkbh)Br]·H2O from dmso or CH3CN produced dark red crystals of [MnII(κ3-Npy,Nim,O-dpkbh-H)2]·nX (X = dmso, n = 1 and X = H2O, n = 0.22). This is in contrast to the reaction of [Re(CO)5Cl] with dpkbh in refluxing toluene to form fac-[ReI(CO)3(κ2-,Npy,Npy-dpkbh)Cl] which can be crystallized from CH3CN, dmso or dmf to form fac-[ReI(CO)3(κ2-,Npy,Npy-dpkbh)Cl]·nX (X = CH3CN, n = 0 and solvate = dmso or dmf, n = 1). Infrared spectral measurements are consistent with keto coordination of dpkbh to Mn(I) in fac-[MnI(CO)3(κ2-Npy,Nim-dpkbh)Br]·H2O and Mn(II) in [MnIIBr2(κ3-Npy,Nim,O-dpkbh)] plus enol coordination of the amide-deprotonated dpkbh, to the Mn(II) center in [MnII(κ3-Npy,Nim,O-dpkbh-H)2]·0.5H2O. Electronic absorption spectral measurements in non-aqueous solvents indicate sensitivity of fac-[MnI(CO)3(κ2-Npy,Nim-dpkbh)Br]·H2O and [MnII(κ3-Npy,Nim,O-dpkbh-H)2]·0.5H2O to changes in their outer-shell environments. X-ray crystallographic analyses elucidated the identities of [MnIIBr2(κ3-Npy,Nim,O-dpkbh)] and [MnII(κ3-Npy,Nim,O-dpkbh-H)2]·nX and divulged weaker coordination of [dpkbh] to Mn(II) in [MnIIBr2(κ3-Npy,Nim,O-dpkbh)] and stronger coordination of [dpkbh-H]? to Mn(II) in [MnII(κ3-Npy,Nim,O-dpkbh-H)2]·0.22H2O. Low-temperature X-ray structural analyses were employed to account for the disorder in the structure of [MnII(κ3-Npy,Nim,O-dpkbh-H)2] and the short NH bond distance observed in the structure of [MnIIBr2(κ3-Npy,Nim,O-dpkbh)]. A PLATON Squeeze treatment was invoked to account for the fractional occupancy of lattice water in the structure of [MnII(κ3-Npy,Nim,O-dpkbh-H)2].  相似文献   

8.
Summary The seven-coordinate complexes [MI2(CO)3(NCMe)2] (M=Mo or W) react with two equivalents of L(L=py, 4Me-py, 3Cl-py or 3Br-py) or one equivalent of NN {NN=2,2-bipyridine(bipy), 1,10-phenanthroline(phen), 5,6-dimethyl-1, 10-phenanthroline (5,6-Me2-1, 10-phen), 5-Nitro-1, 10-phenanthroline (5-NO2-1, 10-phen) and C6H4(o-NH2)2 (o-diam) (for M=Mo only)} in CH2Cl2 at room temperature to give the substituted products [MI2(CO)3L2] or [MI2(CO)3(NN)] (1–17) in high yield. The compounds [MI2(CO)3(NCMe)2] react with two equivalents of NN (for M=W, NN=bipy; for M=Mo, NN=phen) to give the dicationic salts [M(CO)3(NN)2]2I(18–19). The compounds [MI2(CO)3(NCMe)2] (M=Mo or W) react with two equivalents of 5,6-Me2-1, 10-phen to yield the monocationic dicarbonyl compounds [MI(CO)2(5,6-Me2-phen)2]I (20 and21). The dicationic mixed ligand complexes [M(CO)3(bipy)(5,6-Me2-phen)]2I (22 and23) are prepared by reacting [MI2(CO)3(NCMe)2] with one equivalent of bipy, followed by anin situ reaction with 5,6-Me2-1, 10-phen to afford the products22 and23. The complexes (1–23) described in this paper have been characterised by elemental analysis (C, H and N), i.r. spectroscopy and, in selected cases,1Hn.m.r. spectroscopy. Magnetic susceptibility measurements show the compounds to be diamagnetic.  相似文献   

9.
The reaction of K2Fe(CO)4 with (CO)4 M(AsMe2Cl)2 (M  Cr, Mo, W) gives low yields of the new heterodinuclear complexes (CO)4M-[μ-AsMe2]2-Fe(CO)3 with CrFe, MoFe and WFe bonds.  相似文献   

10.
The crystal structure of trans-pyH[MoBr4py2] has been determined: orthorhombic, Pnma (No. 62), a = 16.197(3), b = 13.995(3), c = 8.615(1) Å, Z = 4, Dc = 2.23, Do = 2.20(3) g/cm3, V = 1 953(1) Å3. R1, Rw = 0.057 and 0.053. Trans-[MoBr4py2]? anions with staggered conformation of pyridine rings are located on the mirror planes. Mo? Br, Mo? N(pyridine) distances are 2.593(1), 2.573(1), 2.227(8) and 2.213(7) Å. Cations are located on the symmetry centers. The cation in trans-pyH[MBr4py2] can be replaced. Trans-NH4[MBr4py2] · H2O, Cs[MBr4py2], LH[MBr4py2] (M = Mo, W; L = 4-methylpyridine, 4-pic; 2,2′-bipyridyl, bipy) were prepared. The compounds of molybdenum and tungsten with the same chemical composition are isostructural. All compounds react with pyridine and 4-methylpyridine. The products are trans-MBr3L3, and in the case of molybdenum, also trans-MoBr3py2(4-pic). Bromine oxidizes trans-MI[MBr4py2] to trans-MBr4py2.  相似文献   

11.
With the aim to determine the effect of Lewis acidity of rhenium(I) carbonyl complexes on their catalytic properties, and to develop more efficient catalysts based on Re(I) carbonyl systems, a series of rhenium(I) carbonyl triflate complexes with various degrees of Lewis acidity was investigated. Pyridine-substituted bromo tricarbonyl rhenium(I) complexes of the type fac-[ReBr(CO)3L2] (L = py-Cl, py, py-Me and py-NMe2) were synthesized from [ReBr(CO)5] using trimethylamine N-oxide (TMNO) as decarbonylating agent. The complexes [ReBr(CO)5] and fac-[ReBr(CO)3L2] were then reacted with silver triflate to yield the complexes [Re(CF3SO3)(CO)5] and fac-[Re(CF3SO3)(CO)3L2]. The synthesis and characterization of these complexes and their application in the catalysis of the cyclization of 6-aminohex-1-yne are discussed. The crystal structure of [Re(CF3SO3)(CO)3(py)2] is also presented.  相似文献   

12.
Treatment of M(allyl)(Cl)(CO)2(py)2 (M = Mo, W) with 1 equiv. of potassium pyrazolates in tetrahydrofuran at −78 °C afforded M(allyl)(R2pz)(CO)2(py)n (R2pz = 3,5-disubstituted pyrazolate; n = 1, 2) in 68-81% yields. X-ray crystal structure analyses of Mo(allyl)((CF3)2pz)(CO)2(py)2 and W(allyl)(tBu2pz)(CO)2(py) revealed η1- and η2-coordination of the (CF3)2pz and tBu2pz ligands, respectively. Analogous treatment of Mo(allyl)(Cl)(CO)2(NCCH3)2 with 1 equiv. of tBu2pzK in tetrahydrofuran at −78 °C afforded [Mo(allyl)(tBu2pz)(CO)2]2 in 79% yield. An X-ray crystal structure analysis of [Mo(allyl)(tBu2pz)(CO)2]2 showed a dimeric structure bridged by two μ-η2:η1-tBu2pz ligands. Treatment of M(allyl)(Cl)(CO)2(py)2 with 1 equiv. of lithium 1,3-diisopropylacetamidinate or lithium 1,3-di-tert-butylacetamidinate in diethyl ether at −78 °C afforded M(allyl)(iPrNC(Me)NiPr)(CO)2(py) and M(allyl)(tBuNC(Me)NtBu)(CO)2(py), respectively, in 68-78% yields. The new complexes were characterized by spectral and analytical methods and by X-ray crystal structure determinations. M(allyl)(iPrNC(Me)NiPr)(CO)2(py) adopt pseudo-octahedral geometry about the metal centers, with the 1,3-diisopropylacetamidate ligand nitrogen atoms spanning one axial site and one equatorial site of the octahedron. By contrast, M(allyl)(tBuNC(Me)NtBu)(CO)2(py) adopt pseudo-octahedral structures in which the two 1,3-di-tert-butylacetamidinate ligand nitrogen atoms span two equatorial coordination sites. Sublimation of M(allyl)(tBuNC(Me)NtBu)-(CO)2(py) at 105 °C/0.03 Torr afforded ?7% yields of M(allyl)(tBuNC(Me)NtBu)(CO)2, along with sublimed M(allyl)(tBuNC(Me)NtBu)(CO)2(py). W(allyl)(tBuNC(Me)NtBu)(CO)2 exists in the solid state as a 16-electron complex with distorted square pyramidal geometry. Many of the new complexes undergo dynamic ligand site exchange in solution, and these processes were probed by variable temperature 1H NMR spectroscopy. The volatilities and thermal stabilities were evaluated to determine the potential of the new complexes for use as precursors in thin film growth experiments.  相似文献   

13.
From measurements of the heats of iodination of CH3Mn(CO)5 and CH3Re(CO)5 at elevated temperatures using the ‘drop’ microcalorimeter method, values were determined for the standard enthalpies of formation at 25° of the crystalline compounds: ΔHof[CH3Mn(CO)5, c] = ?189.0 ± 2 kcal mol?1 (?790.8 ± 8 kJ mol?1), ΔHof[Ch3Re(CO)5,c] = ?198.0 ± kcal mol?1 (?828.4 ± 8 kJ mo?1). In conjunction with available enthalpies of sublimation, and with literature values for the dissociation energies of MnMn and ReRe bonds in Mn2(CO)10 and Re2(CO)10, values are derived for the dissociation energies: D(CH3Mn(CO)5) = 27.9 ± 2.3 or 30.9 ± 2.3 kcal mol?1 and D(CH3Re(CO)5) = 53.2 ± 2.5 kcal mol?1. In general, irrespective of the value accepted for D(MM) in M2(CO)10, the present results require that, D(CH3Mn) = 12D(MnMn) + 18.5 kcal mol?1 and D(CH3Re) = 12D(ReRe) + 30.8 kcal mol?1.  相似文献   

14.
The kinetics of the iodine cleavage of the SnCo bond in [Me3SnCo(CO)4 ] and of the SnRe bond in [Me3SnRe(CO)5] have been measured. The order of rates of cleavage of the SnM bond in the compounds [Me3SnM(CO)x(cp)y] (M = Mn, Re, x = 5, y = 0;M = Co, x = 4, y = 0; M = Cr, Mo, W, x = 3, y = 1; M = Fe, x = 2, y = 1; cp = η-cyclopentadienyl) indicates that the main factors determining reactivity towards iodine are the size of the metal atom (M) and the shielding of it by the other ligands.  相似文献   

15.
Determination of the electronic structure was performed by the parameter-free Fenske-Hall method for the complexes [(CO)5MHM(CO)5]− with D4h, C2v and C2 symmetries (wehre M = Cr, Mo) as well as for the complex [(CO)3NiHNi(CO)3]− with C2v and D3h symmetries and for the complex [(CO)4FeHFe(CO)4]+ with a D3h symmetry.The character and stability of the metalhydrogenmetal bridge bond in each of these complexes was compared. The effect of lowering the symmetry on the electronic structure of these complexes is also discussed. The influence of the bridging hydrogen atom on terminal ligands, i.e. its cis effect, was characterized.  相似文献   

16.
Oxidation of [Re3(μ-H)4(CO)10]? with CF3SO3H in acetonitrile gives the new complex Re3(μ-H)3(CO)10(NCMe)2. This contains a triangle of metal atoms with the edges bridged by the hydrides (mean ReRe 3.266 Å). The acetonitrile ligands, bound to two metals in a trans-diaxial manner, are easily replaced, giving a variety of derivatives.  相似文献   

17.
Compounds M(η3-C3H5)(CO)2(NCCH3)2(NCBH3) and [N(CH3)4]2[M(η3-C3H5)(CO)2(NCBH3)3] (M = Mo, W) were prepared and structurally characterized. In the solid state, the allyl group orients its open face to the two carbonyl groups producing an endo form in the above compounds. In solution, an exo form coexists with an endo form in compound Mo(η3-C3H5)(CO)2(NCCH3)2(NCBH3). The cyanotrihydroborate ligand bonds to the metal through a nitrogen atom. Both of the IR and the 11B NMR spectroscopic data suggest the negative charge of the cyanotrihydroborate ligand on the complex is almost localized on the BH3 and this negative charge only has small effect on the metal-nitrogen interaction.  相似文献   

18.
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19.
《Polyhedron》1987,6(4):685-693
The strength of multiple metal-metal bonds in the metal dimers M2 (M = Cr, Mo or W) and binuclear complexes M2(OH)6 (M = Cr, Mo or W), M2Cl4(PH3)4 M = V, Cr, Mn, Nb, Mo, Tc, Ta, W or Re) has been studied by a non-local density functional theory. The method employed here provides metal-metal bond energies [D(M-M)] in good accord with experiments for Cr2 and Mo2, and predicts that W2 of the three dimers M2 (M = Cr, Mo or W) has the strongest metal-metal bond with D(W-W) = 426 kJ mol−1 and R(W-W) = 2.03 Å. Among the binuclear complexes studied here we find the 3d elements to form relatively weak metal-metal bonds (40–100 kJ mol−1), compared to the 4d and 5d elements with bonding energies ranging from 250 to 450 kJ mol−1. The metal-metal bond for a homologous series is calculated to be up to 100 kJ mol−1 stronger for the 5d complex, than for the 4d complex. An energy decomposition of D(M-M) revealed that the σ-bond is somewhat stronger than each of the π-bonds, and one order of magnitude stronger than the δ-bond. For the same transition metal we find D(M-M) to be larger for M2(PH3)4Cl4 (M = Cr, Mo or W) than for M2(OH)6 (M = Cr, Mo or W), and attribute this to a stronger π-interaction in the former series. While many of the findings here are in agreement with previous HFS studies, the order of stability D(3d-3d) « D(4d-4d) < D(5d-5d) differs from the order D(3d-3d) « D(5d-5d) < D(4d-4d) obtained by the HFS method, and the present method provides in general more modest values for D(M-M) than the HFS scheme.  相似文献   

20.
Direct measurement of the enthalpy of decomposition of HCr(CO)3C5H5 to [Cr(CO)3C5H5]2 and H2 was made by differential scanning calorimetry. The heat of hydrogenation of 1,3-cyclohexadiene by HM(CO)3C5H5 for M = Cr, Mo, and W was measured by solution calorimetry. The enthalpies of iodination of [M(CO)3C5H5]2 and HM(CO)3C5H5 were measured for M = Mo and W. These data have been used to calculate the heats of hydrogenation for each of the metal—metal bonded dimers, [M(CO)3C5H5]2 (M = Cr, Mo, and W).C5H5(CO)3M-M(CO)3C5H5(s) + H2(g) → 2HM(CO)3C5H5(s)Addition of hydrogen has been found to be exothermic for M = Cr, W (?3.3 kcal/mol and ?1.5 kcal/mole, respectively) but endothermic for M = Mo (+6.3 kcal/mol). These results are consistent with the trend of increasing MH bond strengths upon descending Group VI. Addition of H2 to [Cr(CO)3C5H5]2 is favored by the unusually weak chromium—chromium bond.  相似文献   

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