Studies on K2CO3-catalyzed 1,4-addition of 1,2-allenic ketones with diethyl malonate: controlled selective synthesis of beta,gamma-unsaturated enones and alpha-pyrones

The K2CO3 (10 mol %)-catalyzed 1,4-addition reaction of diethyl malonate with various substituted 1,2-allenic ketones leading to polyfunctionalized beta,gamma-unsaturated enones 3 or 4 was studied. With 3-unsubstituted 1-substituted-1,2-allenyl ketones, the highly selective formation of beta,gamma-unsaturated enones 4 was observed; with 1,2-allenyl ketones bearing one or two 3-substituents in the allenyl group, only beta,gamma-unsaturated enones 3 with an unmigrated carbon-carbon double bond were produced; with 3-monosubstituted-1,2-allenyl ketones Z-beta,gamma-unsaturated enones 3 were formed with excellent stereoselectivity (E:Z > 96:4); with propadienyl ketones, mixtures of beta,gamma-unsaturated enones 3 and 4 were formed. alpha-Pyrone derivatives were synthesized via the K(2)CO(3)-catalyzed or -promoted reaction of 1,2-allenic ketones with diethyl malonate via a sequential Michael addition-carbon-carbon double bond migration-lactonization process.     

General, stereoselective synthesis of (Z)-beta,gamma-unsaturated nitriles promoted by samarium diiodide

A method to obtain (Z)-beta,gamma-unsaturated nitriles in high or good yields and with moderate or high stereoselectivity is described. The products were achieved through the photoinduced metalation of 3-acetoxy-4-chloronitriles with SmI2. The starting compounds were readily prepared, and a mechanism is proposed to explain this stereoselective beta-elimination reaction.     

Formation of Chiral β-Silyl-Vinyl Ethers

Chiral formates derived from propane-1,2-diol, 1,2- O -isopropylidene- f - D -xylo- and f - D -gluco-furanoses were subjected to treatment with cyclopentadienyl [tris(trimethylsilylmethyl)] titanium (IV). A mixture of the corresponding ( E )- and ( Z )- g -silylvinyl ethers were obtained with predominance of the former. It was found that in contrast to ( Z )-vinyl ethers, which give g -lactams with chlorosulfonyl isocyanate, the ( E )-vinyl ethers gave unstable cycloadducts which undergo rapid elimination reaction leading to ( E )- f , g -unsaturated amides.     

Zirconium-mediated intramolecular ester transfer reaction: synthesis of alpha-substituted gamma-aminobutyric acid (GABA) derivatives

[reaction: see text]. The zirconium-mediated intramolecular ester transfer reaction of N-alkenyl carbamate derivatives proceeded to give alpha-substituted gamma-aminobutyric acid (GABA) derivatives in good to excellent yields. Quenching experiments of the reaction mixture with iodine or O2 indicated the presence of a cyclopropane intermediate. The resulting iodide was converted to 2-substituted pyrrolidine-3-carboxylate and/or alpha-alkylidene-gamma-aminobutyric acid derivatives in a stereospecific manner.     

Manganese(III) acetate-mediated free radical reactions of [60]fullerene with beta-dicarbonyl compounds

[60]Fullerene reacted with various beta-dicarbonyl compounds in the presence of Mn(OAc)3*2H2O to generate dihydrofuran-fused [60]fullerene derivatives or 1,4-bisadducts. Dihydrofuran-fused [60]fullerene derivatives 2 could be formed by treatment of alpha-unsubstituted beta-diketones 1a-e or beta-ketoesters 1f and 1g with [60]fullerene in refluxing chlorobenzene in the presence of Mn(III). Solvent-participated unsymmetrical 1,4-bisadducts 3 were obtained through the reaction of [60]fullerene with dimethyl malonate 1h or alpha-substituted beta-dicarbonyl compounds 1i-1n in toluene. A possible reaction mechanism for the formation of different fullerene derivatives is proposed.     

Syntheses and characterizations of three-dimensional channel-like polymeric lanthanide complexes constructed by 1,2,4,5-benzenetetracarboxylic acid

The hydrothermal reaction of YbCl(3) small middle dot6H(2)O with 1,2,4,5-benzenetetracarboxylic dianhydride resulted in [[Yb((b)btec)(1/4)((d)btec)(3/6)(H(2)O)(2)](4).6H(2)O](n)() (1) (H(4)btec = 1,2,4,5-benzenetetracarboxylic acid), and the solvothermal reaction of Er(NO(3))(3) small middle dot6H(2)O or TbCl(3).6H(2)O with 1,2,4,5-benzenetetracarboxylic dianhydride in H(2)O/acetic acid gave rise to [[Er(2)((c)btec)(2/4)((e)btec)(2/4)((f)btec)(2/4)(H(2)O)(4)].4H(2)O](n)() (2) and [[Tb(H(2)btec)(2/4)((f)btec)(3/6)(H(2)O)].2H(2)O](n)() (3), respectively. Complex 1 crystallizes in monoclinic space group C2/m with a = 20.8119(5) A, b = 17.6174(1) A, c = 5.7252(2) A, beta = 92.324(1) degrees, and Z = 1. 1 possesses a three-dimensional framework consisting of eight-coordinate ytterbium centers and two kinds of channels along the c axis. Complex 2 crystallizes in triclinic space group P with a = 9.6739(5) A, b = 11.0039(5) A, c = 11.5523 A, alpha = 104.8330(10) degrees, beta = 91.0000(10) degrees, gamma = 114.2570(10) degrees, and Z = 2. 2 has a three-dimensional framework comprising both eight- and nine-coordinate erbium centers and channels along the a axis. Complex 3 crystallizes in monoclinic space group P2(1)/n with a = 10.7246(12) A, b = 7.1693(9) A, c = 17.158(2) A, beta = 97.109(2) degrees, and Z = 4. 3 shows a three-dimensional framework containing nine-coordinate terbium centers and channels along the b axis. Uncoordinated water molecules occupy the channels in the three complexes. TGA and XRPD were determined for the three complexes, and the results illustrate that the framework of 1 is retained upon removal of uncoordinated and coordinated water molecules.     

Coordination of lanthanide triflates and perchlorates with N,N,N',N'-tetramethylsuccinamide

Compounds formed from the reaction of N,N,N',N'-tetramethylsuccinamide (TMSA) with trivalent lanthanide salts possessing the poorly coordinating counteranions triflate (CF3SO3-) and perchlorate (ClO4-) have been prepared and examined. Structural features of these Ln-TMSA compounds have been studied in the solid phase by thermogravimetric analysis, infrared spectroscopy, and, in selected cases, by single-crystal X-ray diffraction and in solution by infrared spectroscopy. Eight-coordinate compounds, [Ln(TMSA)4]3+, derived from coordination of four succinamide ligands to the metal ion could be formed with all lanthanides examined (Ln = La, Pr, Nd, Eu, Yb, Lu). Structural analyses by single-crystal X-ray diffraction were performed for the lanthanide triflate salts Ln(C8H16N2O2)4(CF3SO3)3: Ln = La, compound 1, monoclinic, P2(1)/n, a = 11.0952(2) A, b = 19.2672(2) A, c = 24.9759(3) A, beta = 90.637(1) degrees, Z = 4, Dcalcd = 1.586 g cm-3; Ln = Nd, compound 2, monoclinic, C2/c, a = 24.6586(10) A, b = 19.3078(7) A, c = 11.1429(4) A, beta = 90.450(1) degrees, Z = 4, Dcalcd = 1.603 g cm-3; Ln = Eu, compound 3, monoclinic, C2/c, a = 24.4934(2) A, b = 19.3702(1) A, c = 11.1542(1) A, beta = 90.229(1) degrees, Z = 4, Dcalcd = 1.617 g cm-3; Ln = Lu, compound 5, monoclinic, C2/c, a = 24.2435(4) A, b = 19.6141(2) A, c = 11.2635(1) A, beta = 90.049(1) degrees, Z = 4, Dcalcd = 1.626 g cm-3. X-ray analysis was also carried out for the perchlorate salt: Ln = Eu, compound 4, triclinic, P1, a = 10.9611(2) A, b = 14.6144(3) A, c = 15.7992(2) A, alpha = 106.594(1) degrees, beta = 91.538(1) degrees, gamma = 90.311(1) degrees, Z = 2, Dcalcd = 1.561 g cm-3. In the presence of significant amounts of water, 7-coordinate compounds with mixed aquo-TMSA cation structures [Ln(TMSA)3(H2O)]3+ (Ln = Yb) and [Ln(TMSA)2(H2O)3]3+ (Ln = La, Pr, Nd, Eu, Yb) have been isolated with structural determinations by single-crystal X-ray diffraction obtained for the following species: Yb(C8H16N2O2)3(H2O)(CF3SO3)3, compound 6, monoclinic, P2(1)/n, a = 8.9443(3) A, b = 11.1924(4) A, c = 44.2517(13) A, beta = 93.264(1) degrees, Z = 4, Dcalcd = 1.735 g cm-3; Yb(C8H16N2O2)3(H2O)(ClO4)3, compound 7, monoclinic, Cc, a = 19.2312(6) A, b = 11.1552(3) A, c = 19.8016(4) A, beta = 111.4260(1) degrees, Z = 4, Dcalcd = 1.690 g cm-3; Yb(C8H16N2O2)2(H2O)3(CF3SO3)3, compound 8, triclinic, P1, a = 8.6719(1) A, b = 12.2683(2) A, c = 19.8094(3) A, alpha = 75.815(1) degrees, beta = 86.805(1) degrees, gamma = 72.607(1) degrees, Z = 2, Dcalcd = 1.736 g cm-3. Unlike in the analogous nitrate salts, only bidentate binding of the succinamide ligand to the lanthanide metal is observed. IR spectroscopy studies in anhydrous acetonitrile suggest that the solid-state structures of these Ln-TMSA compounds are maintained in solution.     

Ruthenium hydride-catalyzed addition of aldehydes to dienes leading to beta,gamma-unsaturated ketones

An efficient cross-addition reaction of dienes with aldehydes was developed by using RuHCl(CO)(PPh3)3 as a catalyst to give a wide variety of beta,gamma-unsaturated ketones, where a pi-allylruthenium species, derived from hydroruthenation of diene, may be involved as a key intermediate.     

Mn(III)-Based Oxidative Free-Radical Cyclizations of Unsaturated Ketones

Mn(III)-based oxidative free-radical cyclization of unsaturated ketones is a versatile synthetic procedure with broad applicability. For example, oxidation of cyclopentanone 1a with 2 equiv of Mn(OAc)(3).2H(2)O and 1 equiv of Cu(OAc)(2).H(2)O in AcOH at 80 degrees C for 1.5 h affords 75% of bicyclo[3.2.1]oct-3-en-8-one 8a and 15% of bicyclo[3.2.1]oct-2-en-8-one 9a. Bridged bicyclic ketones that cannot enolize further are isolated in good yield. Monocyclic beta,gamma-unsaturated ketones that can enolize are oxidized further to give gamma-acetoxy enones. The formation of bicyclo[3.3.1]non-2-en-9-one (57a) in 52% yield from 2-allylcyclohexanone (56a) suggests that kinetically controlled enolization is the rate-determining step in alpha-keto radical formation. A wide variety of examples delineating the scope, limitations, and stereoselectivity of this reaction are presented.     

Total synthesis of natural (+)-(2's,3'r)-zoapatanol

[reaction: see text] (+)-Zoapatanol was synthesized by using four key-steps: a Suzuki cross-coupling to prepare a (Z)-alpha,beta-unsaturated ester followed by an enantioselective dihydroxylation to control the C2' and C3' stereocenters, an intramolecular Horner-Wadsworth-Emmons olefination to construct the oxepane ring, and a chemoselective nucleophilic addition/Birch reduction process of a Weinreb amide to introduce simultaneously the beta,gamma-unsaturated ketone on the side-chain and regenerate alcohols from benzyl ethers.     

Palladium complex catalyzed acylation of allylic esters with acylstannanes: complementary method to the acylation with acylsilanes

Palladium-catalyzed acylation of allylic trifluoroacetates (2) using acylstannanes (1) is reported. The reaction serves as a complementary method to the previously reported acylation with acylsilane (4). In particular, the reaction is profitable in the acylation of unsubstituted allyl trifluoroacetate (2a) and benzoylation of allylic trifluoroacetates to afford synthetically useful beta,gamma-unsaturated ketones (3) in good yields without undesirable isomerizations.     

Reactions of [(eta(6)-arene)RuCl(2)](2) with Aromatic Phosphines Containing Methoxy Groups in 2,6-Positions

Reactions of [(eta(6)-arene)RuCl(2)](2) 1 (arene = p-cymene (a), 1,2,3,4-Me(4)C(6)H(2) (b), 1,2,3-Me(3)C(6)H(2) (c)) with tris(2,6-dimethoxyphenyl)phosphine (TDMPP) led to loss of two molecules of CH(3)Cl to give (eta(6)-arene)Ru[{2-O-C(6)H(3)-6-OMe}(2){C(6)H(3)(OMe)(2)-2,6}], 2a-c, which contains a trihapto ligand (eta(3)-P,O,O) derived from TDMPP, whereas the 1,3,5-Me(3)C(6)H(3) (1d), 1,2,3,5-Me(4)C(6)H(2) (1e), and C(6)Me(6) (1f) complexes did not react with TDMPP. The structures of 2a and 2b were confirmed by X-ray analyses: for 2a, a = 11.691(2) ?, b = 15.228(2) ?, c = 10.320(1) ?, alpha = 95.93(1) degrees, beta = 113.783(9) degrees, gamma = 83.86(1) degrees, triclinic, P&onemacr;, Z = 2, R = 0.051; for 2b, a = 17.79(2) ?, b = 15.43(1) ?, c = 20.93(1) ?, beta = 91.25(8) degrees, monoclinic, P2(1)/n, Z = 8, R = 0.056. Bis(2,6-dimethoxyphenyl)phenylphosphine (BDMPP) reacted with 1a, 1b, and 1d at room temperature to give (eta(6)-arene)RuCl[PPh(2-O-C(6)H(3)-6-OMe){C(6)H(3)(OMe)(2)-2,6}], 3a,b,d, which contains a dihapto (eta(2)-P,O) ligand derived from BDMPP by an X-ray analysis of 3a: a = 12.33(1) ?, b = 14.246(8) ?, c = 11.236(9) ?, alpha = 91.47(8) degrees, beta = 117.28(6) degrees, gamma = 111.70(6) degrees, triclinic, P&onemacr;, Z = 2, R = 0.040. A similar reaction with 1f recovered the starting materials, but that in refluxing MeCN produced [(eta(6)-C(6)Me(6))Ru[PPh(2-O-C(6)H(3)-6-OMe}(2)], 4f, containing a trihapto (eta(3)-P,O,O) ligand derived from BDMPP. Complex 1d reacted with BDMPP at reflux in MeCN/CH(2)Cl(2) and resulted in a loss of an arene ring to give a five-coordinate complex, Ru[eta(2)-P,O-PPh(2-O-C(6)H(3)-6-OMe){C(6)H(3)(OMe)(2)-2,6}](2)(MeCN), 5. Treatment of (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) with 1f gave (eta(6)-C(6)Me(6))RuCl[eta(2)-P,O-PPh(2)(2-O-C(6)H(3)-6-OMe)],6f, and that with 1b gave (eta(6)-1,2,3,4-Me(4)C(6)H(2))RuCl[eta(2)-P,O-PPh(2)(2-O-C(6)H(3)-6-OMe}], 6b, and (eta(6)-1,2,3,4-Me(4)C(6)H(2))RuCl(2)[eta(1)-P-PPh(2){C(6)H(3)(OMe)(2)-2,6}],7b. The phosphine ligand of 6b acted as a bidentate ligand derived from MDMPP: a = 8.074(4) ?, b = 16.816(3) ?, c = 18.916(4) ?, beta = 94.05(3) degrees, monoclinic, P2(1)/n, Z = 4, R = 0.051. Transformation of 7b to 6b readily occurred accompanying an elimination of MeCl. Reaction of 1a with MDMPP eliminated an arene ring to give the octahedral compound RuCl(2)[eta(2)-P,OMe-PPh(2){C(6)H(3)(MeO)(2)-2,6}](2), 8. An X-ray analysis of 8 showed that two MDMPP ligands were in a cis-position: a = 10.596(14) ?, b = 27.586(12) ?, c = 13.036(8) ?, beta = 108.17(7) degrees, monoclinic, P2(1)/n, Z = 4, R = 0.035.     

Revised structure of a purported 1,2-dioxin: a combined experimental and theoretical study

3,6-Bis(p-tolyl)-1,2-dioxin (1g) was suggested by Shine and Zhao as a product in an electron-transfer (ET) photochemical reaction. This photoproduct is instead shown to be (E)-1,4-di-p-tolylbut-2-ene-1,4-dione ((E)-4a). Ab initio and DFT calculations indicate that ring-closed 1,2-dioxin is thermodynamically far less stable than open-chain but-2-ene-1,3-dione. These calculations indicate that (E)-4a is formed via the cation radical of 1g, which sequentially isomerizes to a novel sigma-radical with an O,O 3e bond [(Z)-4a](+)(*), undergoes ET to give (Z)-4a, and then photoisomerizes to (E)-4a.     

From metallacyclophanes to 1-D coordination polymers: role of anions in self-assembly processes of copper(II) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole

The reaction of various CuII salts with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L) in CH3CN-H2O medium affords different complexes, the solid structures of which are controlled only by the choice of the counteranions. Reaction of Cu-(ClO4)2.6H2O or Cu(NO3)2.3H2O and L yields the novel bimetallic macrocyclic complex [Cu2L2(H2O)6](ClO4)4(H2O)4 (1) [monoclinic, space group P21/m, a = 8.745(5) A, b = 16.179(10) A, c = 14.930(8) A, beta = 93.253(10) degrees, Z = 2] or [CuL(NO3)2]2(CH3CN)2 (2) [triclinic, space group P1, a = 7.863(3) A, b = 8.679(3) A, c = 13.375(5) A, alpha = 74.121(5) degrees, beta = 78.407(6) degrees, gamma = 86.307(6) degrees, Z = 1]. However, with the replacement of CuII perchlorate or nitrate salts with CuSO4.5H2O or Cu(OAc)2.H2O in the above reaction, two different one-dimensional (1-D) coordination polymers [[Cu2L2(H2O)6(SO4)2](H2O)6]n (3) [triclinic, space group P1, a = 7.078(3) A, b = 11.565(4) A, c = 12.561(5) A, alpha = 109.511(6) degrees, beta = 105.265(6) degrees, gamma = 94.042(6) degrees, Z = 1] or [[Cu2L(mu-OAc)4]]n (4) [monoclinic, space group C2/c, a = 20.007(7) A, b = 7.506(2) A, c = 16.062(5) A, beta = 108.912(5) degrees, Z = 4] were obtained. These results unequivocally indicate that the nature of the counteranions, which play different roles in each complex, is the key factor governing the structural topologies of them. The magnetic properties of these CuII complexes have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, and the magneto-structural correlation has been analyzed in detail.     

Calix[4]arene rhenium(V) complexes as potential radiopharmaceuticals

The calix[4]arene platform was used for the syntheses of novel rhenium(V) complexes, that may have potential applications as radiopharmaceuticals. The reaction of ReO(PPh3)2Cl3 with tetradentate N2O2-calix[4]arene ligand 8 in ethanol gave the novel mixed-ligand rhenium complex 9 with the structure ReO(N2O2-calix)OEt. The configuration was elucidated by using a number of 1H NMR techniques. In 9, the ethoxy ligand could be easily and quantitatively exchanged for another monodentate ligand to give complex 12. Tetradentate N2S2-calix[4]arene ligand 15 formed the rhenium complex 16 either via reaction with ReO(PPh3)2Cl3 in an organic solvent or by reaction with rhenium gluconate in an aqueous solution. Complex 16 showed good stability in phosphate-buffered saline solution (37 degrees C, 5 d). The crystal structures of a mono- and a bimetallic complex were determined. The bimetallic N2O2-calixarene complex dimer 11 crystallized in the monoclinic space group C2/c, with a = 38.963(5) A, b = 23.140(6) A, c = 27.382(6) A, beta = 128.456(10) degrees, V = 19,333(7) A3, Z = 8, and final R = 0.0519. The monometallic N2S2 model complex 17 crystallized in the monoclinic space group Cc, with a = 15.715(2) A, b = 12.045(2) A, c = 20.022(3) A, beta = 94.863(12) degrees, V = 3776.3(10) A3, Z = 4, and final R = 0.0342.     

Structure-based description of a step-by-step synthesis of homo- and heterodinuclear (4f, 4f ') lanthanide complexes

The stepwise course of the synthesis of homo- (4f, 4f) and heterodilanthanide (4f, 4f ') complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, the tripodal ligand H(3)L is reacted with Ln(NO(3))(3) x 5H(2)O to give a complex (H(3)L)Ln(NO(3))(3) in which the ligand does exist in a zwitterionic form. This unexpected feature has been definitely supported by a structural determination performed on a closely related complex (HL')(3)Ln(NO(3))(3) (1). These species are fairly stable and may be isolated. In basic medium, (H(3)L)Ln(NO(3))(3) is deprotonated to yield a neutral LLn complex crystallized as LLnNaClO(4) (2), the lanthanide ion being linked to the inner N(4)O(3) coordination site of the ligand. Finally, addition of Ln'(NO(3))(3) x 5H(2)O (Ln' being similar or different from Ln) to the LLn complex yields the desired homo- or heterodinuclear LLnLn'(NO(3))(3) complex 3, where the Ln' ion is coordinated to the outer O(3)O(3) coordination site of the tripodal ligand. Complex 1 (Ln = La) crystallizes in the triclinic space group P1 (No. 2): a = 11.1883(7) A, b = 11.8993(9) A, c = 16.4197(10) A, alpha = 81.900 (6) degrees, beta = 79.406(5) degrees, gamma = 79.470(6) degrees, V = 2099.5(2) A(3), Z = 2. Complex 2 (Ln = Eu) crystallizes in the monoclinic space group P2(1)/n (No. 14): a = 13.6333(13) A, b = 15.3799(12) A, c = 17.1473(13) A, beta = 111.283(10) degrees, V = 3350.2(5) A(3), Z = 4. Complex 3 (Ln = Ln' = Dy) crystallizes in the trigonal space group R3 (No. 148) with a = b = 23.847(3) A, c = 42.982(2) A, V = 21168(4) A(3), Z = 18. Complex 3 possesses a Dy(O(phenoxo))(3)Dy core, and a nitrato anion has been replaced by a eta(2)-chelated o-vanillin anion. We did not succeed in obtaining crystals of any of the heterodinuclear LLnLn'(NO(3))(3) entities, but their existence was unambiguously confirmed by positive fast atom bombardment mass spectrometry experiments.     

Thermal Coupling Reactions of 1-Phenyl-3,4-dimethylphosphole within the Coordination Sphere of Palladium(II)

The thermolyses of dihalobis(1-phenyl-3,4-dimethylphosphole)palladium(II) complexes [(DMPP)(2)PdX(2), X = Cl, Br, I] were investigated in 1,1,2,2-tetrachloroethane solutions at 145 degrees C and in the crystalline state at 140 degrees C. For cis-(DMPP)(2) PdCl(2) and cis- or trans-(DMPP)(2) PdBr(2) four types of products were formed: (1) [4 + 2] cycloaddition products, (2) [2 + 2] cycloaddition products, (3) compounds that result from 1,5-hydrogen migration from a methyl group on one phosphole to the beta-carbon of an adjacent phosphole (exo-methylene), and (4) products that result from an intermolecular [4 + 2] coupling of two phospholes followed sequentially by phosphinidene elimination and intramolecular [4 + 2] cycloaddition to another phosphole to give diphosphatetracyclotetradecatrienes (DPTCT). trans-(DMPP)(2)PdBr(2) undergoes thermal isomerization to cis-(DMPP)(2)PdBr(2) in the solid state, and cis- and trans-(DMPP)(2)PdBr(2) give the same products in both their solid- and solution-state thermolyses. In contrast, trans-(DMPP)(2) PdI(2) neither isomerizes to the cis-isomer nor undergoes any of the phosphole coupling reactions in either the solution or solid state. The crystal structures of trans-(DMPP)(2)PdX(2) (X = Br, I), {(DMPP)(2)[2 + 2]}PdBr(2), {(DMPP)(2)(exo-methylene)}PdBr(2), and (DPTCT)PdCl(2) were determined. They crystallize in the monoclinic P2(1)/c, triclinic P&onemacr;, monoclinic P2(1)/c, monoclinic P2(1)/n, and orthorhombic P2(1)2(1)2(1) space groups in units cells of the following dimensions: a = 10.158 (3) ?, b = 14.876 (4) ?, c = 16.829 (5) ?, beta = 104.25(2) degrees, rho(calc) = 1.732 g/cm(3), Z = 4; a = 9.025(1) ?, b = 11.023(1) ?, c = 13.833 (1) ?, alpha = 101.15(1) degrees, beta = 98.82(1) degrees, gamma = 105.30(1) degrees, rho(calc) = 1.886 g/cm(3), Z = 2; a = 13.090 (2) ?, b = 17.637 (2) ?, c = 21.834 (2) ?, beta = 100.51 (1) degrees, rho(calc) = 1.738 g/cm(3), Z = 4, a = 10.721 (1) ?, b = 16.929 (1) ?, c = 14.675(1) ?, beta = 97.86 (1) degrees, rho(calc) = 1.663 g/cm(3), Z = 4; and a = 15.532 (3) ?, b = 19.401 (4) ?, c = 9.910 (2) ?, rho(calc) = 1.490 g/cm(3), Z = 2, respectively. Least-squares refinements converged at final values of R(F) of 0.041, 0.0354, 0.0624, 0.0533, and 0.035 for 2770, 2672, 2729, 2159, and 2525 independent observed reflections, respectively. Kinetic studies suggest that the reaction mechanisms are the same in both the solid and solution states and that the reaction mechanisms are substantially different from those previously reported for the thermolyses of the analogous cis-(DMPP)(2)PtX(2) complexes.     

Insertion of SO(2) into the S-S bond of Cp(2)MoS(2) and Cp(2)MoS(2)O to give molybdocene dithiosulfate and bis(O-alkylthiosulfates)

Cp(2)MoS(2), 3, reacts with SO(2) in CH(2)Cl(2)/EtOH mixtures to give Cp(2)MoS(3)O(2), 4, wherein the SO(2) has inserted into the S-S bond to give a dithiosulfate ligand. Crystal data for 4: P2(1)/n, a = 7.6782(6) A, b = 14.580(3) A, c = 10.2730(10) A, beta = 92.04(1) degrees, V = 1149(3) A(3), Z = 4. Cp(2)MoS(2)O, 5, reacts with SO(2) in CH(2)Cl(2) to give low yields of 4 plus other identified products. 5 reacts with SO(2) in MeOH and EtOH to give the corresponding bis(O-alkylthiosulfate), 6a and 6b, respectively. Crystal data for 6a: P 1 macro, a = 8.3226(13) A, b = 8.4736(11) A, c = 12.382(2) A, alpha = 87.803(11) degrees, beta = 77.758(11) degrees, gamma = 86.383(12) degrees, V = 851.4(2) A(3), Z = 2.     

Synthesis, structures, and magnetic properties of tetranuclear CuII-LnIII complexes

The copper(II)-gadolinium(III) and copper(II)-terbium(III) complexes studied in this report derive from disymmetric trianionic ligands abbreviated H3Li (i = 4-6). These ligands are obtained through reaction of different aldehydes with "half-units" having an amide function, the latter resulting from the monocondensation of different diamines with phenyl 2-hydroxy-3-methoxybenzoate. Upon deprotonation, the Li ligands (i = 4-10) possess an inner N2O2 coordination site with one amido, one imine, and two phenoxo functions, an outer O2O2 or O2O coordination site, and an amido oxygen atom positioned out of these two sites. The trianionic character of such ligands yields original anionic complexes in the presence of copper(II) or nickel(II) ions, with a 1/1 L/M stoichiometry. The crystal and molecular structures of four complexes, two 3d (1, 5) and two 3d-4f (12, 13) complexes, have been determined. Complex 1 crystallizes in the monoclinic space group C2/c: a = 27.528(2) A, b = 7.0944(7) A, c = 22.914(2) A, beta = 92.130(6) degrees , V = 4471.9(7) A(3), Z = 8 for C(21.5)H(27)CuKN(2)O(6.5). Complex 5 crystallizes in the monoclinic space group P2(1)/n (No. 14): a = 11.0760(9) A, b = 21.454(2) A, c = 15.336(1) A, beta = 101.474(1) degrees , V = 3571.5(5) A(3), Z = 4. Complex 12 crystallizes in the triclinic space group P (No. 2): a = 8.682(2) A, b = 11.848(2) A, c = 11.928(2) A, alpha = 81.77(3) degrees , beta = 89.17(3) degrees , gamma = 85.49(3) degrees , V = 1210.6(4) A(3), Z = 2 for C20H22CuN5O11Tb. Complex 13 belongs to the monoclinic space group C2/c: a = 25.475(5)A, b = 12.934(3)A, c = 15.023(3) A, beta = 91.06(3) degrees , V = 4949.02A3, Z = 8 for C21H25CuN4O12Tb. The structural determinations confirm that the dinuclear entities involved in 12 and 13 are disposed in a head-to-tail arrangement to give tetranuclear complexes in which the copper and lanthanide ions are positioned at the vertexes of a rectangle. In the [Cu-Gd]2 species, there are two different ferromagnetic Cu-Gd interactions. The stronger one is supported by the double phenoxo bridge (CuO2Gd) while the weaker one corresponds to the single amido bridge (Cu-N-C-O-Gd). Replacement of gadolinium ions with anisotropic terbium ions yields tetranuclear entities showing slow relaxation of magnetization and magnetization hysteresis. Detailed relaxation and hysteresis loop studies establish single-molecule magnet (SMM) behavior which is influenced by weak intermolecular interactions.     

Rearrangement of homoallylic alcohols induced by DAST

[reaction: see text] Treatment of beta,gamma-unsaturated monoprotected 1,2-diols with diethylaminosulfur trifluoride (DAST) allows the stereoselective formation of beta,gamma-unsaturated aldehydes in good yields and with a good transfer of chirality.