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ABSTRACT: The ligand substitution chemistry of the hexaruthenium cluster Ru(6)(mu(6)-C)(CO)(17) () with several unsaturated diphosphine ligands has been investigated. Thermolysis of with (Z)-Ph(2)PCH[double bond, length as m-dash]CHPPh(2) (dppen) furnishes the new cluster compounds Ru(5)(mu(5)-C)(CO)(12)(mu(3)-dppen) (), Ru(6)(mu(6)-C)(CO)(14)(mu(3)-dppen) (), and Ru(6)(mu(6)-C)(CO)(12)(mu(3)-dppen)(mu-dppen) (). Clusters and are also obtained when a mixture of and dppen is treated with the oxidative-decarbonylation reagent Me(3)NO. Thermolysis or Me(3)NO activation of in the presence of 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) yields Ru(6)(mu(6)-C)(CO)(14)(mu(3)-bpcd) () as the sole observable product. Near-UV irradiation of leads to P-C bond cleavage and the formation of phosphido-bridged cluster Ru(6)(mu(6)-C)(CO)(13)[mu(3)-C[double bond, length as m-dash]C(PPh(2))C(O)CH(2)C(O)](mu-PPh(2)) () in essentially quantitative yield. The reaction between and the ligand 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf) leads to the formation of Ru(6)(mu(6)-C)(CO)(14)(mu(3)-bmf) (), which exists as a single diastereomer in solution as shown by (1)H and (31)P NMR spectroscopy. The molecular structures and the binding mode of the ancillary diphosphine ligand(s) in have all been established by X-ray diffraction analyses. The solid-state structure of reveals that the chiral bmf ligand caps one of the metallic faces stereospecifically with the 5-methoxy moiety oriented distal or trans relative to the Ru(6) polyhedral core. The new substitution products are discussed relative to the products obtained from and the related diphosphine ligands dppm, dppe, dppf, and dppbz.
Dalton Transactions 02/2010; 39(6):1620-9. · 3.84 Impact Factor
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ABSTRACT: The reaction of H2Re2(CO)8 (1) with Cp*Rh(CO)2 (2) in refluxing hexane affords the mixed-metal clusters H2RhRe2Cp*(CO)9 (4, major product), HRh2ReCp*2(CO)6 (5), and HRhRe3Cp*(CO)14 (6). 4 and 5 are electron-precise 48e clusters and display triangular metallic cores, while 6 contains 64 valence electrons and exhibits a spiked-triangular core having a pendant Re(CO)5 moiety. Heating 1 with Cp*2Rh2(CO)2 (3) gives 4 and 5 as the principal products, in addition to H2Rh2Re2Cp*2(CO)8 (7) in low yield. Cluster 7 possesses 60e and contains a tetrametallic core with two face-capping CO and hydride groups. Heating 4 under CO leads to cluster fragmentation and formation of Re2(CO)10 and 2 in essentially quantitative yield, as assessed by IR spectroscopy. The kinetics for the fragmentation of 4 in toluene under CO have been investigated over the temperature range 325−349 K by UV−vis spectroscopy. On the basis of the first-order rate constants and the Eyring activation parameters (ΔH = 25.0(8) kcal/mol; ΔS = −2.6(3) eu), a rate-limiting step involving a polyhedral opening of 4 is supported. 4 is thermally and photochemically sensitive, and reactions conducted in the presence of chlorinated solvents furnish the face-shared bioctahedral compound Cp*Rh(μ-Cl)3Re(CO)3 (8). Heating 4 and H2S in benzene at ca. 60 °C furnishes the 48e triangular cluster S2Rh3Cp*(CO)4 (9), which contains two Rh(CO)2 moieties and two face-capping sulfide groups. The reaction of 4 with p-methylbenzenethiol gives the sulfido-bridged dimer Cp*Rh(μ-SC6H4Me-p)3Re(CO)3 (11). The dinuclear compounds Cp*Rh(μ-Cl)(μ-SC6H4Me-p)2Re(CO)3 (10) and 11 are formed when 8 is allowed to react with p-methylbenzenethiol. Treatment of 8 and 10 with excess p-methylbenzenethiol yields 11 at elevated temperature in toluene. Compounds 4−11 have been isolated and fully characterized by IR and NMR spectroscopy and by X-ray crystallography. The reactivity displayed by 4 is contrasted with that of the known indenyl-substituted cluster H2Re2Ir(η5-ind)(CO)9 prepared earlier by Shapley and co-workers.
12/2009;
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ABSTRACT: The synthesis and full characterization (mp, NMR, UV/vis, FTIR, and elemental analysis) of 13 bismuth aryloxides are reported. We have prepared bismuth aryloxides with alkyl, aryl, and allylic substituents on the aryl rings. Eleven of these bismuth aryloxides have been characterized with single crystal X-ray diffraction methods. Bismuth-donor interactions (donor = aryl, methoxy) are observed in several cases. Three unexpected bismuth oxo aryloxides (6c, 9c, 11c) were also isolated. Complex C(77)H(102)Bi(4)Br(6)O(8) (6c) results from apparent C-H activation and Bi-C bond formation as a sideproduct in the synthesis of Bi(O-2,6-(i)Pr(2)-4-BrC(6)H(2))(3) (6). Cluster 9c has a Bi(32)O(56) core, and cluster C(90)H(90)Bi(4)Li(2)O(12) (11c) is the second lithium bismuth oxo cluster reported to date.
Inorganic Chemistry 11/2009; 48(23):11002-16. · 4.60 Impact Factor
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ABSTRACT: AbstractThermolysis of mixed-metal tetrahedrane cluster HCCo2MoCp(CO)8 (1) with the diphosphine ligand 2,3–bis(diphenylphosphino)maleic anhydride (bma) furnishes the cluster compounds HCCo2MoCp(CO)6[trans-2,3-bis(diphenylphosphino)succinic anhydride] (2), HCCo2MoCp(CO)6(bma) (3), and Co2MoCp(CO)6[μ–C=C(H)CH2C(PPh2)C(PPh2)C(O)OC(O)] (4) in low yields (<13%). The tungsten congener HCCo2WCp(CO)8 (5) reacts with bma to give Co2WCp(CO)6[μ–C=C(H)CH2C(PPh2)C(PPh2)C(O)OC(O)] (6) as the sole isolable product in 3% yield. The new clusters have been fully characterized in solution by IR and NMR spectroscopies,
and the solid-state structures of the vinylidene-bridged clusters 4 and 6 established by X-ray crystallography. Clusters 4 and 6 each contain 48e- and exhibit triangular Co2M cores, with a vinylidene moiety that caps one of the Co2M faces. The reactivity differences exhibited by clusters 1 and 5 with bma are contrasted with similar data from the substitution reaction of bma with the related cluster compounds PhCCo2MoCp(CO)8 and PhCCo2WCp(CO)8.
Index AbstractThe mixed-metal cluster HCCo2MoCp(CO)8 (1) reacts with the diphosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) at elevated temperature to afford the
new clusters HCCo2MoCp(CO)6[trans-2,3-bis(diphenylphosphino)succinic anhydride] (2), HCCo2MoCp(CO)6(bma) (3), and Co2MoCp(CO)6[μ–C=C(H)CH2C(PPh2)C(PPh2)C(O)OC(O)] (4). Thermolysis of HCCo2WCp(CO)8 (5) with bma furnishes only Co2WCp(CO)6[μ–C=C(H)CH2C(PPh2)C(PPh2)C(O)OC(O)] (6) in trace amounts. The presence of the face-capping vinylidene ligand in clusters 4 and 6 has been confirmed by spectroscopic methods and X-ray crystallography.
Journal of Chemical Crystallography 01/2008; 38(6):437-445. · 0.57 Impact Factor
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ABSTRACT: Benzonorbornadiene and heterobenzonorbornadiene were reacted with dimedone/acetylacetone and Mn(OAc)3 in the presence and absence of Cu(OAc)2. The reaction of benzonorbornadiene with dimedone gave mainly the dihydrofuran addition product, whereas the reaction with acetylacetone produced a rearranged product in addition to the dihydrofuran derivative. On the other hand, oxanorbornadiene gave unusual products such as the cycloproponated compound and a product arising from the incorporation of 2 mol of dimedone. The reaction of azanorbornadiene with 1,3-dicarbonyl compounds and Mn(OAc)3 always produced rearranged products. The mechanism of formation of the products is discussed. We generally observe that the cyclization reaction takes place after the oxidation of the initially formed radical.
The Journal of Organic Chemistry 05/2007; 72(9):3353-9. · 4.45 Impact Factor
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ABSTRACT: Photochemical activation of the bpcd-chelated cluster 1,1-Os3(CO)10(bpcd) (1) in the presence of P(OEt)3 furnishes the simple substitution product 1,1,2-Os3(CO)9[P(OEt)3](bpcd) (2) initially, followed by the formation of the hydride cluster HOs3(CO)7[P(OEt)3][μ-{PPh(C6H4)}C=C(PPh2)C(O)CH2C(O)] (3). Both new clusters were isolated and characterized in solution by IR and NMR (1H and 31P) spectroscopies, with the solid-state structure of cluster 3 determined by X-ray diffraction analysis. Cluster 3 crystallizes in the triclinic space group P−1, a=9.366(2)Å, b=14.182(4)Å, c=17.672(4)Å, α=87.787(4)°, β=78.488(4)°, γ=71.785(4)°, V=2184.1(9)Å3, Z=2, D
cacl=2.123Mg/m3; R=0.0488, R
w=0.1059 for 8527 observed reflections with I > 2σ(I). The presence of the seven-electron ligand μ-P{Ph(C6H4)}C=C(PPh2)C(O)CH2C(O) that caps one of the triangular faces in 3 through both phosphine moieties, the π bond of the dione ring, and an ortho-metalated aryl ligand is established.
Journal of Chemical Crystallography 03/2007; 37(4):247-253. · 0.57 Impact Factor
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ABSTRACT: The tetraruthenium cluster H4Ru4(CO)12 (1) has been studied for its reactivity with the unsaturated diphosphine ligands (Z)–Ph2PCH–CHPPh2 and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) under thermal, near-UV photolysis, and Me3NO-assisted activation. All three cluster activation methods promote loss of CO and furnish the anticipated substitution products H4Ru4(CO)10[(Z)–Ph2PCH–CHPPh2] (2) and H4Ru4(CO)10(bpcd) (3) that possess a chelating diphosphine ligand. Clusters 2 and 3 have been characterized in solution by IR and NMR spectroscopies, and these data are discussed with respect to the crystallographically determined structure for both new cluster compounds. The 31P NMR spectral data and the solid-state structures confirm the presence of a chelating diphosphine ligand in clusters 2 and 3. Cluster 2 crystallizes in the monoclinic space P21/c, a=11.768(6)Å, b=18.521(9)Å, c=20.48(1)Å, β=102.291(8)°, V=4361(4) A3, Z=4, and d
calc=1.726Mg/m3; R=0.0225, R
w=0.0491 for 6798 reflections with I > 2σ(I). The four bridging hydrides were located in H4Ru4(CO)10[(Z)–Ph2PCH–CHPPh2] and their adopted positions are discussed relative to the solution 1H NMR spectrum. H4Ru4(CO)10(bpcd) crystallizes in the orthorhombic space Pbca, a=19.072(3)Å, b=20.169(3)Å, c=22.774(3)Å, V=8760(2) A3, Z=8, and d
calc=1.870Mg/m3; R=0.0428, R
w=0.0896 for 10296 reflections with I > 2σ(I). Sealed NMR tubes containing clusters 2 and 3 were found to be exceeding stable towards near-UV light and temperatures up to ca. 125°C. The surprisingly robust behavior of 2 and 3 is contrasted with the related cluster Ru3(CO)10(bpcd) that undergoes fragmentation to the donor-acceptor compound Ru2(CO)6(bpcd) and the phosphido-bridged compound Ru2(CO)6(μ–PPh2)[μ–C–C(PPh2)C(O)CH2C(O)] under mild conditions. The electrochemical properties of each substituted cluster have been investigated by cyclic voltammetry, and our findings are discussed with respect to the reported electrochemical data on the parent cluster H4Ru4(CO)12.
Journal of Chemical Crystallography 11/2006; 36(12):813-822. · 0.57 Impact Factor
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ABSTRACT: The structure of an unexpected compound from the dehydration of an aldol addition product has been determined using 1-D and 2-D NMR techniques. This reaction is the last step in a new synthetic approach to the galanthan ring system. Complete 1H and 13C NMR assignments for two synthetic precursors are also reported.
Magnetic Resonance in Chemistry 11/2006; 44(10):969-71. · 1.44 Impact Factor
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ABSTRACT: We report a series of calix[4]arene Mo(VI) dioxo complexes M2RC4MoO2 (M = alkali metal, R = H or Bu(t)) that were fully characterized by NMR, X-ray, IR, UV/vis, and elemental analysis. Molybdocalix[4]arene structures can be controlled via lower rim deprotonation, groups at para positions of calix[4]arene, and alkali metal counterions. Mono deprotonation at the lower rim leads to calix[4]arene Mo(VI) monooxo complexes RC4MoO (R = H, Bu(t), or allyl), and full deprotonation gives rise to calix[4]arene Mo(VI) dioxo complexes. Structural studies indicate that HC4 Mo(VI) dioxo complexes easily form polymeric structures via cation-pi interaction and coordination between different calixarene units. However, Bu(t)C4 Mo(VI) dioxo complexes tend to form dimers or tetramers due to steric hindrance of the tert-butyl groups at para positions in calixarene. The structures of the reduced side products A and C were determined by X-ray diffraction studies. The mechanism of RC4MoO formation from the reaction of calixarene monoanions with MoO2Cl2 appears to include the addition of a calixarene -OH group across a Mo=O bond.
Inorganic Chemistry 06/2006; 45(10):4247-60. · 4.60 Impact Factor
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ABSTRACT: The substitution chemistry of the activated clusters Os3(CO)10(MeCN)2 (1) and Os3(CO)10(1,5-cod) (2) has been investigated with the bidentate ligand 1,2-bis(dimethylphosphino)ethane (dmpe). Both starting clusters react rapidly with dmpe at room temperature to give the corresponding substitution product Os3(CO)10(dmpe) (3), whose isomeric composition is shown to depend on the nature of the starting cluster. Whereas the bridged cluster 1,2-Os3(CO)10(dmpe) (3b) was formed almost exclusively upon reaction with Os3(CO)10(MeCN)2, a near statistical mixture of bridging (3b) and chelating (3c) isomers of Os3(CO)10(dmpe) was found in the reaction employing Os3(CO)10(1,5-cod). Both dmpe isomers have been characterized in solution by 3iP NMR spectroscopy and their solid-state structures established by X-ray crystallography. The bridged cluster 1,2-Os3(CO)10(dmpe) crystallizes in the monoclinic space group P21/n, a = 9.867(2), b = 17.081(3), c = 14.198(2), β = 95.902(3), V = 2380.4(6)3, Z = 4, and d
calc = 2.793Mg/m3; R = 0.0435, R
w = 0.0466 for 3519 reflections with I > 2σ(I). The chelated cluster 1,1-Os3(CO)10(dmpe) crystallizes in the orthorhombic space group C222(1), a = 8.329(3), b = 19.028(6), c = 15.008(5), V = 2379(1)3, Z = 4, and d
calc = 2.795Mg/m3; R = 0.0390, R
w = 0.0718 for 2360 reflections with I > 2σ(I).
Journal of Chemical Crystallography 01/2006; 36(2):123-128. · 0.57 Impact Factor
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ABSTRACT: The Knoevenangel condensation between 9-anthracenecarboxaldehyde and the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione (bpcd) takes place rapidly in CH2Cl2/MeOH solution in the presence of molecular sieves (4Å) to produce the functionalized ligand 2-(anthracen-9-ylidene)-4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione. The title compound has been isolated and characterized in solution by IR, NMR, and UV-vis spectroscopies, and the solid-state structure has been established by X-ray diffraction analysis. 2-(anthracen-9-ylidene)-4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione crystallizes in the triclinic space group P−1, a=10.227(2)Å, b=13.865(2)Å, c=15.905(2)Å, α=112.157(2)°, β=101.424(2)°, γ=100.065(3)°, V=1968.5(5)Å3, Z=2, and d
calc=1.101Mg/m3; R=0.0873, R
w=0.2604 for 7452 reflections with I>2σ(I). The cyclic voltammetric behavior for 2-(anthracen-9-ylidene)-4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione has been studied, and the observed redox data and results from extended Hückel MO calculations are discussed relative to the parent ligand bpcd.
Journal of Chemical Crystallography 01/2006; 36(11):715-722. · 0.57 Impact Factor
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ABSTRACT: The reaction between the tetraosmium cluster H4Os4_{4}\hbox{Os}_{4}(CO)12_{12} and the unsaturated diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) has been examined in CH2Cl2_{2}\hbox{Cl}_{2} solvent and in the presence of the oxidative-decarbonylation reagent Me3_{3}NO. Rapid ligand substitution is observed and the four products H4Os4_{4}\hbox{Os}_{4}(CO)11_{11}(NMe3_{3}), 1,1-H4Os4_{4}\hbox{Os}_{4}(CO)10_{10}(bpcd), 1,2-H4Os4_{4}\hbox{Os}_{4}(CO)10_{10}(bpcd), and 1,2-H4Os4_{4}\hbox{Os}_{4}(CO)10_{10}(NMe3_{3}) (h1\eta^{1}-bpcd) have been isolated and characterized in solution by IR and NMR spectroscopies. The molecular structures of H4Os4_{4}\hbox{Os}_{4}(CO)11_{11}(NMe3_{3}) and 1,2-H4Os4_{4}\hbox{Os}_{4}(CO)10_{10}(NMe3_{3})(h1\eta^{1}-bpcd) have been crystallographically determined. H4Os4_{4}\hbox{Os}_{4}(CO)11_{11}(NMe3_{3}) crystallizes in the orthorhombic space group Pca21, a=19.907(3)\hbox{\it Pca}2_{1}, a=19.907(3) Å, b = 8.137(1)b = 8.137(1) Å, c = 13.796(2)c = 13.796(2) Å, V=2234.6(6)V=2234.6(6) Å3, Z=4, and dcalc = 3.353d_{\rm calc} = 3.353 mg/m3; R=0.0418, Rw = 0.1071R=0.0418, R_{\rm w} = 0.1071 for 4997 reflections with $I>2 \sigma(I)$I>2 \sigma(I). 1,2-H4Os4_{4}\hbox{Os}_{4}(CO)10_{10}(NMe3_{3})(h1\eta^{1}-bpcd) crystallizes in the monoclinic space group P21/c, a = 21.0173(3)P2_{1}/c, a = 21.0173(3) Å, b = 10.755(2)b = 10.755(2) Å, c = 23.135(4)c = 23.135(4) Å, V = 4950.5(1)V = 4950.5(1) Å3, Z=4, and dcalc = 2.099d_{\rm calc} = 2.099 mg/m3; R = 0.0591, Rw = 0.1046R = 0.0591, R_{\rm w} = 0.1046 for 10,766 reflections with $I>2\sigma(I)$I>2\sigma(I). The monodentate coordination of the bpcd ligand in 1,2-H4Os4_{4}\hbox{Os}_{4}(CO)10_{10}(NMe3_{3})(h1\eta^{1}-bpcd) and the disposition of the NMe3_{3} and bpcd ligands across one of the Os–Os bonds are crystallographically verified.
Journal of Chemical Crystallography 01/2006; 36(10):605-612. · 0.57 Impact Factor
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ABSTRACT: Treatment of the activated trirhenium cluster H3Re3(CO)10(MeCN)2 with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) in CH2Cl2 does not afford the expected cluster product H3Re3(CO)10(bpcd) but rather the mononuclear complex fac-ClRe(CO)3(bpcd). The identity of fac-ClRe(CO)3(bpcd) was determined in solution by IR and NMR (1H and 31P) spectroscopies and the solid-state structure was established by X-ray diffraction analysis. fac-ClRe(CO)3(bpcd) crystallizes in the triclinic space P-1, a = 9.958(2), b = 11.991(3), c = 13.676(3), α = 73.230(4), β = 73.806(4), γ = 77.409(4), V = 1484.6(6)3, Z = 2, and d
calc = 1.723Mg/m3; R = 0.0367, R
w
= 0.0857 for 4253 reflections with I > 2σ(l).
Journal of Chemical Crystallography 12/2005; 36(1):71-75. · 0.57 Impact Factor
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ABSTRACT: [reaction: see text] endo- and exo-2,3,4,7-tetrahydro-1H-1,4-methanobenzocycloheptene-7-carboxylic acid ethyl esters have been synthesized, and their Diels-Alder cycloaddition reactions with maleic anhydride, dimethyl acetylenedicarboxylate and singlet oxygen have been investigated. The X-ray analysis of four adducts indicated the pyramidalization of the central double bond. Density functional theory calculations on the isolated products and model compounds showed excellent agreement between the experimental and theoretical determined butterfly angles. Furthermore, it has been shown that a cyclopropyl group fused to [2.2.2] system decreases significantly the degree of the pyramidalization which is attributed to the steric interactions between the cyclopropyl group and ethano bridge of the norbornene systems. Due to the instability of the bicyclic endoperoxides, their X-ray analysis could not be carried out. DFT calculations on model compounds showed increased bending in the case of the product obtained by the addition of singlet oxygen to endo-2,3,4,7-tetrahydro-1H-1,4-methanobenzocycloheptene-7-carboxylic acid ethyl ester.
The Journal of Organic Chemistry 08/2005; 70(14):5403-8. · 4.45 Impact Factor
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ABSTRACT: Molybdenum monooxo compoundsMoO(OAr)4-nCln (n=0-2, Ar=2,6-Me2C6H3 or 2,6-i-Pr2C6H3) have been synthesized starting from the dioxo precursor MoO2Cl2. The complexes are characterized spectroscopically and by X-ray diffraction. The formation mechanism likely involves phenol precoordination followed by addition across the Mo=O bond.
Inorganic Chemistry 12/2004; 43(24):7567-9. · 4.60 Impact Factor
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ABSTRACT: The reaction of thiols with the heterocyclic compound 2,3-dichloropyrrolo[1,2-a] benzimidazol-1-one (1) has been investigated as a route to new redox-active, bidentate sulfur ligands. Treatment of 1 with either methylthiol or benzylthiol in the presence of pyridine affords monosulfide compounds 2-chloro-3-methylthiopyrrolo[1,2-a] benzimidazol-1-one (2) and 2-chloro-3-benzylthiopyrrolo[1,2-a]benzimidazol-1-one (3) and the disulfide derivatives 2,3-di(methylthio)pyrrolo[1,2-a]benzimidazol-1-one (4) and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one (5). The substitution of the first chlorine group in 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one (1) occurs regioselectively at C-3 to produce 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one (2) and 2-chloro-3-benzylthiopyrrolo[1,2-a]benzimidazol-1-one (3), followed by replacement of the remaining chlorine group to furnish the disulfide compounds 4 and 5. The new thiols have been isolated by column chromatography and characterized in solution by spectroscopic methods. The molecular structures of 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one have been determined by X-ray crystallography. Compound 2 crystallizes as two independent molecules in the monoclinic space group P21/c, a = 13.221(2) , b = 18.478(2) , c = 8.948(1) , = 100.088(3), V = 2152.3(5) 3, Z = 8, and dcalc = 1.547 Mg/m3; R = 0.0354, Rw = 0.0739 for 2820 reflections with I > 2(I). Compound 5 crystallizes in the triclinic space group P-1, a = 5.180(1) , b = 11.494(2) , c = 17.243(3) , = 86.024(3), = 88.606(4), = 81.235(3), V = 1012.1(4) 3, Z = 2, and dcalc = 1.360 Mg/m3; R = 0.0354, Rw = 0.0692 for 2655 reflections with I > 2(I). The redox properties of the disulfide compounds 4 and 5 have been explored by cyclic voltammetry, where a one-electron reduction at ca. –1.10 V has been observed for each compound. The site of electron accession in has been established by carrying out molecular orbital calculations at the extended Huckel level on the model compound 2,3-di(thio)pyrrolo[1,2-a]benzimidazol-1-one.
Journal of Chemical Crystallography 10/2004; 34(11):773-783. · 0.57 Impact Factor
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ABSTRACT: Refluxing equimolar amounts of 2,3-dichloromaleic anhydride and o-phenylenediamine in toluene affords the three compounds 2,3-dichloro-N-o-C6H4(NH2)maleimide (1), N,N-o-C6H4-bis(2,3-dichloromaleimide) (2), and 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one (3). Under these conditions the former compound is observed as the major product. Repeating the same reaction in the presence of added PTSA furnishes the heterocyclic compound 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one, as the major product. Treatment of compound 1 with PTSA, coupled with water removal, gives compound 3 in near quantitative yield and confirms the intermediacy of 1 en route to 3. The new compounds 1–3 have been isolated by column chromatography and characterized in solution by spectroscopic methods. The molecular structures of the maleimide-substituted compounds 1 and 2 were determined by X-ray crystallography. 2,3-Dichloro-N-o-C6H4(NH2)maleimide crystallizes in the monoclinic space group P21/c, a = 20.693(8) , b = 5.712(2) , c = 8.787(4) , = 92.819(7), V = 1037.3(7) 3, Z = 4, and dcalc = 1.646 Mg/m3; R = 0.0604, Rw = 0.1140 for 1354 reflections with I > 2 (I), with N,N-o-C6H4-bis(2,3-dichloromaleimide) crystallizing in the triclinic space group P–1, a = 7.9509(4) , b = 10.2532(6) , c = 12.1126(7) , = 82.637(1), = 87.799(1), = 71.634(1), V = 929.42(9) 3, Z = 2, and dcalc = 1.651 Mg/m3; R = 0.0499, Rw = 0.1545 for 1977 reflections with I > 2 (I).
Journal of Chemical Crystallography 10/2004; 34(11):757-764. · 0.57 Impact Factor
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ABSTRACT: Replacement of the acetonitrile ligands in Ru3(CO)10(MeCN)2 by the diphosphine ligand 1,2-bis(diphenylphosphino)cyclobutenedione (bpcbd) initially gives the unstable bpcbd-bridged cluster Ru3(CO)10(bpcbd) (1), followed by its subsequent transformation to the triruthenium cluster Ru3(CO)10(bma) (2). The decomposition of cluster 2 serves to produce the ruthenium compounds Ru3(CO)10[2,3-bis(diphenylphosphino)succinic anhydride] (3) and Ru2(CO)6(bma) (4). Compounds 2–4 provide the experimental evidence for the ring expansion of the cyclobutenedione ring via the formal insertion of an oxygen atom into the four-membered ring and hydrogen addition to the bond upon exposure to the atmosphere and/or moisture. Both 3 and 4 have been isolated and characterized in solution by IR and 31P NMR spectroscopies, and the molecular structure of each product has been verified by X-ray crystallography. Ru3(CO)10[2,3-bis(diphenylphosphino)succinic anhydride] crystallizes, as the CH2Cl2 solvate, in the monoclinic space group P21/c, a = 12.178(2), b = 15.988(2), c = 22.472(3), = 95.115(2), V = 4358(1)3, Z = 4, and dcalc = 1.732 Mg/m3; R = 0.0344, Rw = 0.0931 for 5683 reflections with I > 2(I). The dinuclear compound Ru2(CO)6(bma) crystallizes in the triclinic space group P-1, a = 9.298(3), b = 12.020(3), c = 30.858(8), = 81.774(5), = 89.276(5), = 83.545(4), V = 3391(1)3, Z = 4, and dcalc = 1.730 Mg/m3; R = 0.0670, Rw = 0.1444 for 8766 reflections with I > 2a(I).
Journal of Chemical Crystallography 10/2004; 34(11):797-805. · 0.57 Impact Factor
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ABSTRACT: The reaction of p-toluenethiol with 4,5-dichloro-4-cyclopenten-1,3-dione in 1,2-dichloroethane with added DBU affords good yields of the new bidentate sulfide ligand 4,5-bis(p-tolylthio)-4-cyclopenten-1,3-dione. The title compound was isolated by column chromatography and characterized in solution by IR and NMR spectroscopies. The solid-state structure of RC=CRC(O)CH2C(O) (where R = p-tolylthio) was solved by X-ray crystallography. 4,5-Bis(p-tolylthio)-4-cyclopenten-1,3-dione crystallizes in the monoclinic space group P2
1/c, a = 14.203(3) , b = 6.181(1) , c = 20.372(4) , = 106.111(3), V = 1718.1(6) 3, Z = 4, and d
calc = 1.316 mg/m3; R = 0.0743, R
w = 0.1693 for 3958 reflections with I > 2(I). The redox properties of 4,5-bis(p-tolylthio)-4-cyclopenten-1,3-dione have been examined by cyclic voltammetry in CH2Cl2 solution, where a quasireversible reduction wave at –1.10 V was found. The reduction behavior is discussed relative to the nature of the LUMO level, which has been determined by extended Hckel MO calculations. The redox chemistry and the LUMO of our bidentate sulfide ligand are contrasted with the known redox chemistry and the LUMO composition of the corresponding bidentate phosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd).
Journal of Chemical Crystallography 09/2004; 34(10):709-716. · 0.57 Impact Factor
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ABSTRACT: The reaction of p-toluidine with 2,3-dichloromaleic anhydride in the presence of added 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) does not give the known compound 2-chloro-3-p-toluidino-N-p-tolylmaleimide (1), but rather 2-p-toluidino-N-p-tolylmaleimide (2) in low yields. Repeating this same reaction with Et3N, pyridine, tmeda, and 4-Me2Npyridine in place of DBU furnishes the expected product 2-chloro-3-p-toluidino-N-p-tolylmaleimide, without the presence of 2-p-toluidino-N-p-tolylmaleimide. The participation of DBU in the chlorine for hydrogen exchange reaction in compound 1 has been demonstrated from the independent thermolysis reaction of 1 with DBU in toluene, where 2 was obtained as the sole isolable product. Compound 2 was isolated and fully characterized in solution, and the molecular structure was established by X-ray diffraction analysis. 2-p-Toluidino-N-p-tolylmaleimide crystallizes in the monoclinic space C2/c, a = 33.630(5), b = 12.508(2), c = 7.381(1), = 90.668(3), V = 3104.3(8)3, Z = 8, and D
calc = 1.251 Mg/m3; R = 0.0357, R
w = 0.0896 for 2011 reflections with I > 2(I).
Journal of Chemical Crystallography 08/2004; 34(9):621-625. · 0.57 Impact Factor
