The homoallylically substituted alcohols (1-OH and 3-OH) of the sterically congested alkene adamanylideneadamantane (1-H) react with acid catalysis in a solvent of 50% v/v acetic acid:50% v/v aqueous sulfuric acid at 110 degrees C to give a saturated ketone 5, the structure of which has been characterized by H-1 and C-13 NMR spectroscopy and by single-crystal X-ray diffraction. Isotopic labeling studies demonstrate that the reaction involves a stereospecific protonation of the double bond and an intramolecular 1,4-hydride transfer from the secondary alcohol C-H to the other carbon of the olefin. The rearrangement reaction exhibits a kinetic isotope effect (KIE) of 2.34 +/- 0.17 for the intramolecular hydride transfer reaction and a competitive isotope effect of 1.2 for protonation of the olefin. These results are consistent with a two-step reaction in which the protonation of the double bond, a potentially reversible process, is followed by the rate-determining, intramolecular 1,4-hydride transfer.

The nucleophilic addition of oxygen, sulfur, nitrogen and carbon nucleophiles to [Cp∗Re(η3-C3H5)(CO)2][BF4] (1) has been investigated. In all cases, addition of the nucleophile to the allyl ligand in 1 was observed to result, giving the substituted propene complexes with general formula Cp∗Re(CO)2(η2-C3H5R) (RCH3CO2, C2H5S, C6H5S, NH2, CHMe2 and C6H5) and [Cp∗Re(CO)2]2(η2;η2-C3H5S(CH2)3SC3H5). No product of attack at the central carbon was observed for any of the nucleophiles. In the cases where the nucleophile was NH2− or C6H5Li, nucleophilic addition occurred either at the η3-allyl or at a CO ligand. At low temperature (−78-0°C) the CO was attacked and complexes with general formula Cp∗Re(η3-C3H5)(CO)(COR) (R  NH2 and C6H5) were produced. When R is C6H5, the product was stable and was observed along with the substituted propene complex in solution, but when NH2− was used, the carbamoyl complex converted completely to the substituted propene complex at room temperature. A by-product of the method used to synthesize Cp∗Re(η2-C3H5SC6H5)(CO)2 was a small amount of Cp∗Re(η3-C3H5)(CO)(O2CSC6H5) (7). The X-ray crystal structure of 7 has been determined.

Reaction of CpIr(CO)(2) (3, Cp = eta(5)-C(5)Me(5)) with [N(2)Ar][BF(4)] (Ar = p-C(6)H(4)OMe) in acetone at -78 degrees C affords the nitrogen extrusion product [CpIr(CO)(2)(Ar)][BF(4)] (5), but in dichloromethane it yields a dinuclear product [Cp(CO)(2)Ir-Ir(Cl)(CO)Cp][BF(4)] (6). By carrying out this very reaction in ethanol solution, a nitrogen-retained product [CpIr(CO)(OEt)(NHNAr)][BF(4)] (7) is obtained, containing an aryldiazene ligand. Deprotonation of 7 gives quantitatively the neutral doubly-bent aryldiazenido complex CpIr(CO)(OEt)(N(2)Ar) (8). The IR nu(CO) absorptions measured for the dinuclear compound 6 indicate no bridging carbonyl, but a (13)C NMR study in solution shows that 6 is stereochemically nonrigid at ambient temperature; its three carbonyl ligands are all involved in a fast exchange process, and this process is frozen at -86 degrees C. Exchange of the CO groups via a terminal-bridging-terminal process accompanied by rotation about the Ir-Ir axis is suggested. The molecular structure of 6 in the solid state has been established by single crystal X-ray crystallographic analysis and is consistent with the solution spectra. By reaction of [N(2)Ar][BF(4)] with the dinuclear complex [CpIr(CO)](2) (4) in acetone, the complex [{CpIr(CO)}(2)(1-eta(1)-1,2-eta(2)-p-C(6)H(4)OMe)][BF(4)] (9) with a rare sigma,pi-bridging aryl group has been obtained and crystallized. The molecular structure containing an asymmetric bridging aryl group is established for 9 in the solid state by a single crystal X-ray crystallographic analysis. However, the identical (1)H NMR features observed at ambient temperature and -90 degrees C in solution (i.e., a singlet resonance for the two Cp ligands and a symmetric AA'BB' pattern for the p-C(6)H(4)OMe) indicate a static or time-averaged symmetrical molecular geometry for 9. Compound 6 crystallizes in the monoclinic space group P2(1)/c with a = 10.583(2) Å, b = 14.256(3) Å, c= 16.818(4) Å, beta = 95.91 (2) degrees, V = 2523.9 Å(3), and Z = 4. Refinement yielded R(F)() = 0.027 and R(w)(F)() = 0.033 for 3299 observed reflections (I(o) >/= 2.5sigma(I(o))) of 4427 unique reflections. Compound 9 crystallizes in the monoclinic space group P2(1)/n with a = 11.695(2) Å, b = 19.911(3) Å, c= 12.539(2) Å, beta = 96.54(1) degrees, V = 2900.8 Å(3), and Z = 4. Refinement yielded R(F)() = 0.025 and R(w)(F)() = 0.035 for 3444 observed reflections (I(o) >/= 2.5sigma(I(o))) of 4526 unique reflections.

Reaction of Cp*Ir(CO)(2) (3, Cp* = eta(5)-C(5)Me(5)) with [N2Ar][BF4] (Ar = p-C(6)H(4)OMe) in acetone at -78 degrees C affords the nitrogen extrusion product [Cp*Ir(CO)(2)(Ar)][BF4] (5), but in dichloromethane it yields a dinuclear product [Cp*(Co)(2)Ir-Ir(Cl)(CO)Cp*][BF4] (6). By carrying out this very reaction in ethanol solution, a nitrogen-retained product [Cp*Ir(CO)(OEt)(NHNAr)][BF4] (7) is obtained, containing an aryldiazene ligand. Deprotonation of 7 gives quantitatively the neutral doubly-bent aryldiazenido complex Cp*Ir(CO)(OEt)(N2Ar) (8). The IR nu(CO) absorptions measured for the dinuclear compound 6 indicate no bridging carbonyl, but a C-13 NMR study in solution shows that 6 is stereochemically nonrigid at ambient temperature; its three carbonyl ligands are all involved in a fast exchange process, and this process is frozen at -86 degrees C. Exchange of the CO groups via a terminal-bridging-terminal process accompanied by rotation about the Ir-Ir axis is suggested. The molecular structure of 6 in the solid state has been established by single crystal X-ray crystallographic analysis and is consistent with the solution spectra. By reaction of [N2Ar][BF4] with the dinuclear complex [Cp*Ir(CO)](2) (4) in acetone, the complex [{Cp*Ir(CO)}(2)(1-eta(1)-1,2-eta(2)-p-C(6)H(4)OMe)][BF4] (9) with a rare sigma,pi-bridging aryl group has been obtained and crystallized. The molecular structure containing an asymmetric bridging aryl group is established for 9 in the solid state by a single crystal X-ray crystallographic analysis. However, the identical H-1 NMR features observed at ambient temperature and -90 degrees C in solution (i.e., a singlet resonance for the two Cp* ligands and a symmetric AA'BB' pattern for the p-C(6)H(4)OMe) indicate a static or time-averaged symmetrical molecular geometry for 9. Compound 6 crystallizes in the monoclinic space group P2(1)/c with a = 10.583(2) Angstrom, b = 14.256(3) Angstrom, c = 16.818(4) Angstrom, beta = 95.91 (2)degrees, V = 2523.9 Angstrom(3), and Z = 4. Refinement yielded R(F) = 0.027 and R(wF) = 0.033 for 3299 observed reflections (I-o greater than or equal to 2.5 sigma(I-o)) of 4427 unique reflections. Compound 9 crystallizes in the monoclinic space group P2(1)/n with a = 11.695(2) Angstrom, b = 19.911(3) Angstrom, c = 12.539(2) Angstrom, beta = 96.54(1)degrees, V= 2900.8 Angstrom(3), and Z = 4. Refinement yielded R(F) = 0.025 and R(wF) = 0.035 for 3444 observed reflections (I-o greater than or equal to 2.5 sigma(I-o)) of 4526 unique reflections.

The complexes [(OC)4Os(PbMe2)]2 (3) and [(OC)4OsSnBu 2 ′ ]2 (4) have been prepared from be reaction of Na2[Os(CO)4] with Me2PbCl2 and Bu 2 ′ SnCl2, respectively, in THF and their X-ray crystal structures determined. The red derivative,3, was light-sensitive in solution. The reactions or [(OC)4 Os(SnMe2)]2 (2), or its decarbonylated derivative [Os3(CO)7(SnMe2)2]2 (7), with olefins or phosphorus donor ligands have also been investigated, and the structures of two derivatives, viz. [Os2(CO)7(SnMe2)2(C2H4)] (5a) and [Os2(CO)7(SnMe2)2(PMe3)] (6a), have been determined; the noncarbonyl ligand occupies an equatorial site in each case. The X-ray crystal structures of all these compounds, like those of [(OC)4Os(EMe2)]2 (E=Ge (1), Sn (2)) which have been reported previously, show leaning of the axial carbonyl ligands toward the metal tetracycle, i.e., an “umbrella” effect. Crystallographic data for compound3: space group, P21/a;a=13.4404(13) Å,b=10.7494(14) A,c=148967(18) A,β=98.204(9)°,R=0.035, 1983 observed reflections. For compound4: space group,P1;a=9.016(1) Å,b=9.370(1),c=11.334(1) A, α=103.67(1)°,β=100.30(1)°, γ=115.03(1)°, R=0.046, 2026 observed reflections. For compound5a: space group,P1;a=9.2933(11)Å,b=9.7181(3),c=12.2508(15) A, α=89.21(1)°,β=87.61(1)°, γ=86.13(1)°,R=0.038, 2770 observed reflections. For compound6a space groupP1:a=8.7244(9)Å,b=10.9318(6),c=13.2560(13) A, α=87.815(6)°,β=83.655(8)°, γ=82.343(6)°, R=0.030, 3497 observed reflections.

By replacing one or both of the CO groups in [Cp∗Re(η3-C3H5)(CO)2][BF4] (1) by MeCN to give [Cp∗Re(η3-C3H5)(CO)(NCMe)][BF4] (3) or [Cp∗Re(η3-C3H5)(NCMe)2][BF4] (4), it was anticipated that the MeCN groups would be labile and would promote ligand substitutior reactions, leading to a variety of new rhenium η3-allyl half-sandwich derivatives. Instead, MeCN is found to be difficult to substitute, and nucleophiles often result in products that arise from attack at either the MeCN or allyl ligands. Complex 1 reacted with NaBH4 to give the propene complex Cp∗Re(η3-CH2CHCH3)(CO)2 (2), with NaOMe to give the methoxycarbonyl complex Cp∗(η3-C3H5)(CO)(COOMe) (6) and the 3-methoxypropene complex Cp∗Re(η2-CH2CHCH2OMe)(CO)2 (5), and with PMe3 to give [Cp∗Re(η2-CH2CHCH2PMe3)(CO)2][BF4] (7). Complex 3 gave the ethylamine complex [Cp∗C3H5(CO)(NH2Et)][BF4] (8) when reacted with NaBH4, [Cp∗Re(η2-CH2CHCH2PMe3)(CO)(NCMe)][BF4] (9) with PMe3, and Cp∗Re(η-3-C3H5)(CO)(NHCOMe) (10) with NaOH. Complex 4 similarly yielded the bis-ethylamine complex [Cp∗Re(η3-C3H5)(NH2Et)in2][BF4] (11) when reacted with NaBH4, but with PMe3 ligand substitution occurred, resulting in [Cp∗Re(η3-C3H5)(NCMe)(PMe3)][BF4 (12). Treating 12 with NaBH4, or 11 wiht PMe3, yielded the ethylamine complex [Cp∗Re(η3-C3H5)(PMe3)(NH2Et)][BF4] (13). The X-ray crystal structure of [endo-Cp∗Re(η3-C3H5)(NH2Et)2][ReO4].solv has been determined. This compound crystallizes in the space group Pnma with a = 8.6554(8) Å, b = 11.729(2) Å, c = 26.928(3) Å, V = 2733.7 Å3, and Z = 4. The structure was refined to RF = 0.028 for 1444 data (I0 ⩾ 2.5 σ(I0), 2θmax = 46°) and 158 variables. The cation has a crystallographic mirror plane that relates the two EtNH2 ligands and bisects the endo-η3-allyl and Cp∗ ligands. Selected distances and angles are ReN = 2.228(7) Å, ReC(6) = 2.177(9) Å (allyl terminal carbon), ReC(7) = 2.090(13) Å (allyl central carbon), NC(4) = 1.470(10) Å, ReNC(4) = 125.2(6) Å, and C(6)-C(7)-C(6) = 114.1(13) Å

Our Laboratory has been involved in the structure solution and refinement of a number of data sets collected from crystals showing twin lattice symmetry (TLS), this experience has led to procedures which have some general applicability in the structure solution stage where there are a limited number of heavy atoms.The structure solution is sought as if the apparent diffraction symmetry represents untwinned data.The resulting model is then tested against the various alternative space groups by varying only the site occupancies based on the original higher symmetry model.Other experiences with regard to the refinement of twinned data will also be presented.These involve cases where very substantial improvement in the model was achieved by the addition of one variable (twin ratio) to the model.PS02.09.

The complex [(OC)(4)Os(GeMe(2))](2) (1) has been prepared from Na-2[Os(CO)(4)] and Me(2)GeCl(2) in THF. Photolysis of 1 in hexane affords the known [(OC)(3)Os(GeMe(2))](3) (4) as the major product, along with the new clusters Os-3(GeMe(2))(2)(CO)(11) (3) and Os-4(GeMe(2))(4)(CO)12 (5). Pyrolysis of 1, in hexane at 100 degrees C, gives the same compounds except that Os-2(GeMe(2))(3)(CO)(6) (2) was also isolated, albeit in low yield. The structures of 1-5 have been determined; the configurations of 1, 2, and 4 are analogous to those previously found for group 8-group 14 congeners. The skeleton of 3 consists of two Os2Ge triangles that share a common osmium atom, that is, a "bow-tie" arrangement; the Os-Os lengths in 3 are crystallographically equivalent at 2.981(1) Angstrom, and the Os-Ge lengths are 2.520(1) and 2.522(1) Angstrom. The framework of 5 consists of a central triangulated (raftlike) Os3Ge3 unit (similar to that in 4) to one Os atom of which is bound an (Oe)(4)Os(GeMe(2)) fragment so as to give an Os2Ge triangle that lies in the plane of the other metal atoms. The Os-Os bond length associated with this triangle is long (3.069(1) Angstrom), The other Os-Os lengths in 4 range from 2.860(1) to 2.967(1) Angstrom; the Os-Ge lengths are in the range 2.475(2)-2.584(2) Angstrom. The H-1 NMR spectrum of 5 in toluene-d(s) is consistent with rotation of the (OC)(4)Os(GeMe(2)) unit with respect to the rest of the molecule at temperatures above 60 degrees C.

By replacing one or both of the CO groups in [Cp∗Re(η3-C3H5)(CO)2][BF4] (1) by MeCN to give [Cp∗Re(η3-C3H5)(CO)(NCMe)][BF4] (3) or [Cp∗Re(η3-C3H5)(NCMe)2][BF4] (4), it was anticipated that the MeCN groups would be labile and would promote ligand substitutior reactions, leading to a variety of new rhenium η3-allyl half-sandwich derivatives. Instead, MeCN is found to be difficult to substitute, and nucleophiles often result in products that arise from attack at either the MeCN or allyl ligands. Complex 1 reacted with NaBH4 to give the propene complex Cp∗Re(η3-CH2CHCH3)(CO)2 (2), with NaOMe to give the methoxycarbonyl complex Cp∗(η3-C3H5)(CO)(COOMe) (6) and the 3-methoxypropene complex Cp∗Re(η2-CH2CHCH2OMe)(CO)2 (5), and with PMe3 to give [Cp∗Re(η2-CH2CHCH2PMe3)(CO)2][BF4] (7). Complex 3 gave the ethylamine complex [Cp∗C3H5(CO)(NH2Et)][BF4] (8) when reacted with NaBH4, [Cp∗Re(η2-CH2CHCH2PMe3)(CO)(NCMe)][BF4] (9) with PMe3, and Cp∗Re(η-3-C3H5)(CO)(NHCOMe) (10) with NaOH. Complex 4 similarly yielded the bis-ethylamine complex [Cp∗Re(η3-C3H5)(NH2Et)in2][BF4] (11) when reacted with NaBH4, but with PMe3 ligand substitution occurred, resulting in [Cp∗Re(η3-C3H5)(NCMe)(PMe3)][BF4 (12). Treating 12 with NaBH4, or 11 wiht PMe3, yielded the ethylamine complex [Cp∗Re(η3-C3H5)(PMe3)(NH2Et)][BF4] (13). The X-ray crystal structure of [endo-Cp∗Re(η3-C3H5)(NH2Et)2][ReO4].solv has been determined. This compound crystallizes in the space group Pnma with a = 8.6554(8) Å, b = 11.729(2) Å, c = 26.928(3) Å, V = 2733.7 Å3, and Z = 4. The structure was refined to RF = 0.028 for 1444 data (I0 ⩾ 2.5 σ(I0), 2θmax = 46°) and 158 variables. The cation has a crystallographic mirror plane that relates the two EtNH2 ligands and bisects the endo-η3-allyl and Cp∗ ligands. Selected distances and angles are ReN = 2.228(7) Å, ReC(6) = 2.177(9) Å (allyl terminal carbon), ReC(7) = 2.090(13) Å (allyl central carbon), NC(4) = 1.470(10) Å, ReNC(4) = 125.2(6) Å, and C(6)-C(7)-C(6) = 114.1(13) Å

The complex [(eta(5)-C(5)Me(5))Ir(C2H4)(p-N(2)C(6)H(4)OMe)][BF4] (1) reacts with X(-) = I- and Br- to give neutral [(eta(5)-C(5)Me(5))IrX](2)(mu-eta(2)-p-N(2)C(6)H(4)OMe)(mu-eta(1)-p-N(2)C(6)H(4)OMe) where X = I (2) and Br (3), respectively. The spectroscopic data for 2 and 3, as well as their N-15(alpha) derivatives 2a and 3a, establish that 2 and 3 are isostructural in solution and each contains diiridium centers that are bridged by two coordinatively different aryldiazenido ligands, i.e., mu-eta(2)- and mu-eta(1)-p-N(2)C(6)H(4)OMe groups. This structural feature has also been unequivocally confirmed in the solid state by a single-crystal X-ray crystallographic analysis of 2. The NMR studies of the protonation reactions of 2a and 3a indicate that protonation occurs solely at the N-alpha atom of the mu-eta(2)-p-N(2)C(6)H(4)OMe ligand in both cases. When 1 reacts with the metal base complex (eta(5)-C(5)Me(5))Ir(CO)(2) in ethanol at reflux, the monobridging aryldiazenido complex [{(eta(5)-C(5)Me(5))Ir(CO)}(2)(mu-eta(2)-p-N(2)C(6)H(4)OMe][BF4] (6) results. The molecular structure of 6 in the solid state, established by a single-crystal X-ray crystallographic analysis, is consistent with its spectroscopic properties in solution. On the basis of an EHMO calculation and a fragment orbital interaction analysis, a rationale is suggested to explain how the electronic nature of the substituent ligand influences the outcome of substitution reactions of 1. Complex 2 crystallized in the space group <P(1)over bar> with a = 8.937(2) Angstrom, b = 10.036(2) Angstrom, c = 10.893(2) Angstrom, a = 79.98(1)degrees, beta 79.52(1)degrees, gamma = 70.36(1)degrees, and Z = 1. The structure of 2 was refined to R(F) = 0.021 and R(wF) = 0.029 on the basis of 3077 observed independent reflections with I-o greater than or equal to 2.5 sigma(I-o) and 189 variables in the range 28 = 4-52 degrees. Complex 6 crystallized in the space group Pc2lb with a = 8.821(1) Angstrom, b = 20.237(2) Angstrom, c = 34.808(5) Angstrom, and Z = 8. The structure of 6 was refined to R(F) = 0.044 and R(wF) = 0.049 on the basis of 1661 observed independent reflections with I-0 greater than or equal to 2.5 sigma(I-0) and 259 variables in the range 2 theta = 4-50 degrees.

Pyrolysis a the cluster Os3(µ-H h (CO)10 (SnMe2 H) produced an as yet unidentified purple duster, which upon reaction with PEt2Ph at room temperature, gave essentially a quantitative yield of the cluster Os3(µ-H)3(CO)9(µ3-Sn) Os3(µ-H)(CO)10(PEt2Ph), 4. The X-ray structure of 4 (as the toluene solvate) shows that it consists Or two Os, triangles linked through a µ4-Sn unit, such that one of the Os3 triangle is µ3-bonded to the Sn atom (Os-Sn range 2.689(2)–2.707(2) Å) and the other is bonded via a single covalent bond (Os-Sn = 2.643(2) Å). The phosphine ligand occupies the equatorial site on a second osmium atom a be latter Os3 moiety that is syn to the Sn atom; the unique bridging hydride ligarid is believed to occupy a site that Acis to both the P and Sn atoms. Crystallographic data for compound4. 0.5C7H8: space group,P\(\bar 1\); ca= 11862(4) Å,b = 12.940(4) Å,c = 16.513(5) Å, α=68.96(3),β=80.60(3)°,γ=62.49(2).R=0.029, 4118 observed reflections.

The complex [(OC)4Os(GeMe2)]2 (1) has been prepared from Na2[Os(CO)4] and Me2GeCl2 in THF. Photolysis of 1 in hexane affords the known [(OC)3Os(GeMe2)]3 (4) as the major product, along with the new clusters Os3(GeMe2)2(CO)11 (3) and Os4(GeMe2)4(CO)12 (5). Pyrolysis of 1, in hexane at 100 °C, gives the same compounds except that Os2(GeMe2)3(CO)6 (2) was also isolated, albeit in low yield. The structures of 1−5 have been determined; the configurations of 1, 2, and 4 are analogous to those previously found for group 8−group 14 congeners. The skeleton of 3 consists of two Os2Ge triangles that share a common osmium atom, that is, a “bow-tie” arrangement; the Os−Os lengths in 3 are crystallographically equivalent at 2.981(1) A, and the Os−Ge lengths are 2.520(1) and 2.522(1) A. The framework of 5 consists of a central triangulated (raftlike) Os3Ge3 unit (similar to that in 4) to one Os atom of which is bound an (OC)4Os(GeMe2) fragment so as to give an Os2Ge triangle that lies in the plane of the other metal ato...

The complex [(η5-C5Me5)Ir(C2H4)(p-N2C6H4OMe)][BF4] (1) reacts with X- = I- and Br- to give neutral [(η5-C5Me5)IrX]2(μ-η2-p-N2C6H4OMe)(μ-η1-p-N2C6H4OMe) where X = I (2) and Br (3), respectively. The spectroscopic data for 2 and 3, as well as their 15Nα derivatives 2a and 3a, establish that 2 and 3 are isostructural in solution and each contains diiridium centers that are bridged by two coordinatively different aryldiazenido ligands, i.e., μ-η2- and μ-η1-p-N2C6H4OMe groups. This structural feature has also been unequivocally confirmed in the solid state by a single-crystal X-ray crystallographic analysis of 2. The NMR studies of the protonation reactions of 2a and 3a indicate that protonation occurs solely at the Nα atom of the μ-η2-p-N2C6H4OMe ligand in both cases. When 1 reacts with the metal base complex (η5-C5Me5)Ir(CO)2 in ethanol at reflux, the monobridging aryldiazenido complex [{(η5-C5Me5)Ir(CO)}2(μ-η2-p-N2C6H4OMe)][BF4] (6) results. The molecular structure of 6 in the solid state, established by a single-crystal X-ray crystallographic analysis, is consistent with its spectroscopic properties in solution. On the basis of an EHMO calculation and a fragment orbital interaction analysis, a rationale is suggested to explain how the electronic nature of the substituent ligand influences the outcome of substitution reactions of 1. Complex 2 crystallized in the space group P1̄ with a = 8.937(2) Å, b = 10.036(2) Å, c = 10.893(2) Å, α = 79.98(1)°, β = 79.52(1)°, γ = 70.36(1)°, and Z = 1. The structure of 2 was refined to RF = 0.021 and RwF = 0.029 on the basis of 3077 observed independent reflections with Io ≥ 2.5σ(Io) and 189 variables in the range 2θ = 4−52°. Complex 6 crystallized in the space group Pc21b with a = 8.821(1) Å, b = 20.237(2) Å, c = 34.808(5) Å, and Z = 8. The structure of 6 was refined to RF = 0.044 and RwF = 0.049 on the basis of 1661 observed independent reflections with Io ≥ 2.5σ(Io) and 259 variables in the range 2θ = 4−50°.

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Pyrolysis of Cp*Os-4(mu-H)(CO)(12) (Cp* = eta 5-C(5)Me(5)) in solution at 50 degrees C afforded Cp*Os-4(mu-H)(CO)11 (1). The clusters [mu,eta(5),eta(1)-C(5)Me(4)CH(2)]OS4(mu-H)(2)(CO)(10) (2), [mu,eta(6),eta(1)-C(5)Me(4)CH(2)]Os-4(CO)(11) (3), and [mu(3),eta(5),eta(1),eta(1)-C(5)Me(3)(CH2)(2)]Os-4(mu-H)(3)(CO)(9) (4) have been isolated from the pyrolysis of 1 above 90 degrees C. Each tetrahedral cluster has been structurally characterized by X-ray crystallography and thereby provides a unique series of structures that depict the stepwise C-H activation of two methyl groups of a C(5)Me(5) ligand on a metal cluster. The series also allows a comparison of Os-Os lengths of Os-4, Os-4(mu-H), Os-4(mu-H)(2), and Os-4(mu-H)(3) units in a closely related series of clusters. Crystallographic data for compound 1: space group, Pcmn; a = 8.852(1) Angstrom, b = 14.821(2) Angstrom, c = 19.054(2) Angstrom; R = 0.019, 1813 observed reflections. For compound 2: space group, P2(1)/c; a = 9.924(1) Angstrom, b = 17.051(3) Angstrom, c = 15.020(3) Angstrom, beta = 101.81(1)degrees, R = 0.031, 2934 observed reflections. For compound 3: space group, Pbca; a = 14.254(2) Angstrom, b = 16.214(2) Angstrom, c = 21.735(3) Angstrom, R = 0.038, 2197 observed reflections. For compound 4: space group: P2(1)/n; a = 9.655(1) Angstrom, b = 16.380(2) Angstrom, c = 14.842(1) Angstrom, beta = 92.66(1)degrees, R = 0.030, 2822 observed reflections.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of [(.eta.5-C5Me5)Re(PR3)2(p-N2C6H4OMe)][BF4] (R = Me, OMe), X-ray Crystal Structure of [(.eta.5-C5Me5)Re(CO)(PMe3)(p-N2C6H4OMe)][BF4], and an Investigation of Stereochemical Nonrigidity of a Singly-Bent Aryldiazenido LigandAntonio Cusanelli, Raymond J. Batchelor, Frederick W. B. Einstein, and Derek SuttonCite this: Organometallics 1994, 13, 12, 5096–5112Publication Date (Print):December 1, 1994Publication History Published online1 May 2002Published inissue 1 December 1994https://doi.org/10.1021/om00024a061Request reuse permissionsArticle Views55Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (4 MB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

The synthesis of methyl and allyl 5'-thio-alpha-D-kojibiosides and methyl 5'-thio-alpha-D-isomaltoside is described. The phenylselenoglycoside and trichloroacetimidate of 2,3,4,6-tetra-O-acetyl-5-thioglucose have been employed as glycosyl donors to glycosylate glucopyranosyl accepters with 2-OH and 6-OH positions free. The disaccharides thus obtained are potential glucosidase inhibitors. The conformational preferences of allyl 5'-thiokojibioside (34) were studied by comparison of experimental NOE curves with the theoretical counterparts for the corresponding methyl glycoside 25, derived from a Boltzmann-averaged grid search using the program PIMM91. Very goad agreement of experimental NOE curves derived from selective NOE measurements with the theoretical curves is found. The data are consistent with the population of a global minimum structure Phi=-43, Psi-39 degrees) to the extent of 90%, and a second local minimum (Phi=-36, Psi=-173 degrees) to the extent of 6%. An X-ray crystal structure of 34 at 190 K (R=4.2%) indicates a conformation (Phi=-46, Psi=-23 degrees) that is similar to that of the global minimum.