Superacidic activation of 1- and 3-isoquinolinols and their electrophilic reactions

Isomeric 1- and 3-isoquinolinols (11 and 12) when activated in CF(3)SO(3)H-SbF(5) acid system undergo selective ionic hydrogenation with cyclohexane to give 5,6,7,8-tetrahydro-1(2H)- and 5,6,7,8-tetrahydro-3(2H)-isoquinolinones (22 and 27). Under the influence of aluminum chloride similar products were also obtained along with 3,4-dihydro-1(2H)- and 1,4-dihydro-3(2H)-isoquinolinones (23 and 28), respectively. Compounds 11 and 12 also condense with benzene in the presence of aluminum halides, under mild conditions, to give 3,4-dihydro-3-phenyl-1(2H)- and 1,4-dihydro-1-phenyl-3(2H)-isoquinolinones (24 and 29), respectively. Prolonged reaction time or catalysis under strongly acidic HBr-AlBr(3) provides an alternative reaction pathway to yield 5,6-dihydro-6,8-diphenyl-1(2H)- and 5,6,7,8-tetrahydro-6,8-diphenyl-3(2H)-isoquinolinones (25 and 30), respectively. Products 24 and 29 were also found to revert back to 11 and 12 in the presence of aluminum halides in o-dichlorobenzene. The mechanism of these intriguing reactions, which involves superelectrophilic dicationic intermediates, is discussed.     

Notizen zur Synthese sulfonierter Derivate von 5,6,7,8-Tetrahydro-1-naphthylamin und 5,6,7,8-Tetrahydro-2-naphthylamin

Notes on the Synthesis of Sulfonated Derivatives of 5,6,7,8-Tetrahydro-1-naphthylamine and 5,6,7,8-Tetrahydro-2-naphthylamine Sulfonation of 5,6,7,8-tetrahydro-1-naphthylamine ( 1 ) with sulfuric acid gave a mixture of 1-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid ( 2 ), 4-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid ( 13 ) and 4-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid ( 3 ). The same reaction with 5,6,7,8-tetrahydro-2-naphthylamine ( 20 ) yielded 3-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid ( 21 ); formation of 2-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid ( 16 ) or of 3-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid ( 24 ) was not observed. Treatment of 4-bromo-5,6,7,8-tetrahydro-1-naphthylamine ( 4 ) or of its 4-chloro analogue 5 with amidosulfuric acid gave 1-amino-4-bromo-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid ( 9 ) and its 4-chloro analogue 10 , respectively, which were dehalogenated to 2 . Preparations of 13 and 24 were achieved by sulfonation of 5-nitro-1,2,3,4-tetrahydronaphthalene ( 14 ) and 6-nitro-1,2,3,4-tetrahydronaphthalene ( 22 ) to 4-nitro-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid ( 15 ) and 3-nitro-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid ( 23 ), respectively, followed by Béchamp reductions. The sulfonic acid 13 was also obtained by hydrogenolysis of 4-amino-1-bromo-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid ( 11 ) or of its 1-chloro analogue 12 ; compounds 11 and 12 were synthesized from N-(4-bromo-5,6,7,8-tetrahydro-1-naphthyl)acetamide ( 7 ) and from its 4-chloro analogue 8 , respectively, by sulfonation with oleum and subsequent hydrolysis. By ‘baking’ the hydrogensulfate salt of 1 or 20 compounds 3 and 21 were obtained, respectively. Synthesis of 16 was achieved by sulfur dioxide treatment of the diazonium chloride derived from 2-nitro-5,6,7,8-tetrahydro-1-naphthylamine ( 17 ) giving 2-nitro-5,6,7,8-tetrahydronaphthalene-1-sulfonyl chloride ( 18 ), followed by hydrolysis of 18 to the corresponding sulfonic acid 19 and final reduction.     

Zirconium complexes incorporated with asymmetrical tridentate pincer type mono- and di-anionic pyrrolyl ligands: mechanism and reactivity as catalytic precursors

The reactions of Zr(NR(2))(4) (1, R = Me; 2, R = Et) with an asymmetrical tridentate pincer type pyrrole ligand precursor [C(4)H(2)NH(2-CH(2)NH(t)Bu)(5-CH(2)NMe(2))] and treatment of the derivatives with either PhNCS or PhNCO have been carried out and characterized. Reacting Zr(NR(2))(4) (1, R = Me; 2, R = Et) with [C(4)H(2)NH(2-CH(2)NH(t)Bu)(5-CH(2)NMe(2))] generates Zr[C(4)H(2)N(2-CH(2)N(t)Bu)(5-CH(2)NMe(2))](NR(2))(2) (3, R = Me; 4, R = Et) in high yield along with the elimination of 2 equiv of dimethylamine or diethylamine, respectively. Interestingly, while changing the solvent from Et(2)O to CH(2)Cl(2), the complex Zr[C(4)H(2)N(2-CH(2)N(t)Bu)(5-CH(2)NMe(2))][C(4)H(2)N(2-CH(2)NH(t)Bu)(5-CH(2)NMe(2))]Cl (5) is produced by undergoing C-Cl bond cleavage. Furthermore, reaction of either 3 or 4 with 1 or 2 equiv of PhNCS or PhNCO yields Zr[C(4)H(2)N(2-CH(2)N(t)Bu)(5-CH(2)NMe(2))](NMe(2))[PhNC(NMe(2))S] (6), Zr[C(4)H(2)N(2-CH(2)N(t)Bu)(5-CH(2)NMe(2))](NEt(2))[PhNC(NEt(2))O] (7) and Zr[C(4)H(2)N(2-CH(2)NH(t)Bu)(5-CH(2)NMe(2))][PhNC(NEt(2))O](3) (8), respectively. All the aforementioned complexes were characterized by (1)H and (13)C NMR spectrometry and the molecular structures of 5, 6, and 8 have been determined by single-crystal X-ray diffractometry. Complexes 4, 5, and 7 initiated the ethylene polymerization in the presence of MAO as the co-catalyst.     

Building blocks for coordination polymers: self-assembled cleft-like and planar discrete metallo-macrocyclic complexes

Discrete dinuclear metallo-macrocyclic complexes have been prepared from the flexible amide ligand N-6-[(3-pyridylmethylamino)carbonyl]pyridine-2-carboxylic acid (L1-CH(3)), and its more rigid analogue, N-6-[(3-pyridylamino)carbonyl]pyridine-2-carboxylic acid (L3-CH(3)). With ligands L1-CH(3) and L3-CH(3), discrete dinuclear metallo-macrocyclic complexes with the generic formula [Cu(2)(L1-CH(3))(2)(X)(2)(Y)(2)] (7, X = NO(3); 8, X = Cl, Y = H(2)O; 9, X = ClO(4), Y = CH(3)OH) and [Cu(2)(L3-CH(3))(2)(X)(2)(Y)(2)] (10, X = NO(3), Y = H(2)O; 11, X = ClO(4), Y = CH(3)OH) are obtained. For complexes 7-9, containing the more flexible link L1-CH(3), these complexes are cleft-shaped and hinged at the methylene spacer, which allows the cleft to widen and contract to accommodate different packing modes in the solid-state. In contrast, the rigid link L3-CH(3) gives near planar metallo-macrocyclic structures. These metallo-macrocyclic compounds may be useful building blocks for coordination polymers.     

Group 13 organoderivatives supported on a metallic oxide model

The [{TiCp*(micro-O)}3(mu3-CH)] (1) metalloligand, (Cp* = eta5-C5Me5), coordinates in a 1:1 ratio to [AlMe3] or 9-BBN to give [{Me3Al}{(mu3-O)(mu-O)2(TiCp)2(TiCp)3(mu3-CH)}](2) or [{(C8H14)B}(mu-H) {(mu3-O)(mu-O)2(TiCp*)3(mu3-CH)}](4), respectively, partial hydrolysis of 2 leads to the new hydroxo-aluminium derivative [{MeAl} {(mu-OH)(mu3-O)}2{(mu-O)2(TiCp*)3-(mu3-CH)}2](3).     

Nitration of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide with other aromatic substitutions. Isolation and mutagenicity of an α-nitropyridine N-oxide

Treatment of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide ( 2 ) with fuming nitric acid afforded 3-nitro-5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide ( 3 ), an example of formation of an α-nitropyridine N-oxide derivative by nitration of N-oxides. Further reaction of 3 resulted in deoxygenation giving 3-nitro-5,6,7,8-tetrahydro-5,8-methanoisoquinoline ( 4 ). No aromatic nitration was observed by similar treatment of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline ( 1 ) or 5,6,7,8-tetrahydroisoquinoline N-oxide ( 11 ). Some other aromatic substitutions with 1 and 2 were caried out to obtain mainly the 3-substituted derivatives. Significant mutagenicity of 3 is briefly reported.     

Regioselective alkylation of 2-alkyl-5,6,7,8-tetrahydro-3h-cycloheptimidazol-4-ones and 2-alkyl-3h-cycloheptimidazol-4-ones

Regioselective alkylation of 2-alkyl-5,6,7,8-tetrahydro-3H-cycloheptimidazol-4-one (1) and 2-alkyl-3H-cycloheptimidazol-4-one (2) was investigated. 3-[2'-(1-tert-Butyl-1H-tetrazol-5-yl)biphenyl-4-ylmethyl]-2-propyl-5,6,7,8-tetrahydro-1H-cycloheptimidazol-4-one (6) was preferentially obtained under the conditions by using NaH in DMF or THF. On the other hand, 3-[2'-(1-tert-butyl-1H-tetrazol-5-yl)biphenyl-4-ylmethyl]-2-propyl-5,6,7,8-tetrahydro-3H-cycloheptimidazol-4-one (5), the synthetic intermediate compound of Pratosartan, was obtained selectively in the presence of n-Bu(4)NBr in toluene by using aqueous sodium hydroxide as a base. In this reaction, it was found that the concentration of the alkaline solution influences its regioselectivity. This selectivity was observed even for aldehyde and ester derivatives.     

Cyanide-bridged Mn(III)-Fe(III) bimetallic complexes based on the pentacyano(1-methylimidazole)ferrate(III) building block: structure and magnetic characterizations

Seven cyanide-bridged bimetallic complexes have been synthesized by the reaction of [Fe(1-CH3im)(CN)5]2- with Mn(III) Schiff base complexes. Their crystal structure and magnetic properties have been characterized. Five complexes, [Mn2(5-Brsalen)2Fe(CN)5(1-CH3im)] x H2O (1), [Mn2(5-Clsalen)2(H2O)2Fe(CN)5(1-CH3im)] x H2O (2), [Mn2(5-Clsaltn)2(H2O)2Fe(CN)5(1-CH3im)] (3), [Mn2(5-Clsaltmen)2(H2O)2Fe(CN)5(1-CH3im)] x H2O (4), and [Mn2(5-Brsaltmen)2(H2O)2Fe(CN)5(1-CH3im)] x CH3OH (5), are neutral and trinuclear with two [Mn(SB)]+ (SB2- = Schiff base ligands) and one [Fe(1-CH3im)(CN)5]2-. Complex {[Et4N][Mn(acacen)Fe(CN)5(1-CH3im)]}n x 6nH2O (6) is one-dimensional with alternate [Mn(acacen)]+ and [Fe(CN)5(1-CH3im)]2- units. The two-dimensional complex {[Mn4(saltmen)4Fe(CN)5(1-CH3im)]}n[ClO4]2n x 9nH2O (7) consists of Mn4Fe units which are further connected by the phenoxo oxygen atoms. Magnetic studies show the presence of ferromagnetic Mn(III)-Fe(III) coupling in the trinuclear compounds with the magnetic coupling constant (J) ranging from 4.5 to 6.0 cm-1, based on the Hamiltonian H = -2JSFe(SMn(1) + SMn(2)). Antiferromagnetic interaction has been observed in complex 6, whereas ferromagnetic coupling occurs in complex 7. Complexes 6 and 7 exhibit long-range magnetic ordering with a TN value of 4.0 K for 6 and Tc of 4.8 K for 7. Complex 6 shows metamagnetic behavior at 2 K, and complex 7 possesses a hysteresis loop with a coercive field of 500 Oe, typical of a soft ferromagnet.     

Amino-functionalised diarylphosphide complexes of the alkali metals and lanthanum

The secondary phosphines Ar(C6H4-2-CH2NMe2)PH [Ar = mes (3), Tripp (4)] may be isolated in good yields from reactions between Li(C6H4-2-CH2NMe2) and the respective dichlorophosphine, followed by reduction with LiAlH4 [mes = 2,4,6-Me3C6H2, Tripp = 2,4,6-Pri3C6H2]. Metalation of either 3 or 4 with BunLi gives the corresponding lithium compound; the lithium derivative of 3 was isolated as the separated ion pair complex [Li(12-crown-4)2][(mes)(C6H4-2-CH2NMe2)P].THF (5). The lithium complexes Ar(C6H4-2-CH2NMe2)PLi undergo metathesis reactions with either NaOBut or KOBut to give the heavier alkali metal phosphides {Ar(C6H4-2-CH2NMe2)P}M.1/2OEt2 [Ar = mes, M = Na (8), K (9); Ar = Tripp, M = K (10)]. Metathesis reactions between 9 and LaI3(THF)4 give only intractable products; in contrast, a metathesis reaction between 10 and LaI3(THF)4 yields the heteroleptic complex {(Tripp)(C6H4-2-CH2NMe2)P}2LaI (11). Compound 11 reacts cleanly with K{N(SiMe3)2} to give {(Tripp)(C6H4-2-CH2NMe2)P}2La{N(SiMe3)2} (14). Compounds 3-5, 8-11 and 14 have been characterised by multi-element NMR spectroscopy; in addition, compounds 5, 11 and 14 have been studied by X-ray crystallography.     

Syntheses, structures, and reactivities of homometallic rare-earth-metal multimethyl methylidene and oxo complexes

Unsolvated, trinuclear, homometallic, rare-earth-metal multimethyl methylidene complexes [{(NCN)Ln(μ(2)-CH(3))}(3)(μ(3)-CH(3))(μ(3)-CH(2))] (NCN = L = [PhC{NC(6)H(4)(iPr-2,6)(2)}(2)](-); Ln = Sc (2a), Lu (2b)) have been synthesized by treatment of [(L)Ln{CH(2)C(6)H(4)N(CH(3))(2)-o}(2)] (Ln = Sc (1a), Lu (1b)) with two equivalents of AlMe(3) in toluene at ambient temperature in good yields. Treatment of 1 with three equivalents of AlMe(3) gives the heterometallic trinuclear complexes [(L)Ln(AlMe(4))(2)] (Ln = Sc (3a), Lu (3b)) in good yields. Interestingly, 2 can also be generated by recrystallization of 3 in THF/toluene, thereby indicating that the THF molecule can also induce C-H bond activation of 2. Reaction of 2 with one equivalent of ketones affords the trinuclear homometallic oxo-trimethyl complexes [{(L)Ln(μ(2) -CH(3))}(3) (μ(3)-CH(3))(μ(3)-O)] (Ln = Sc(4a), Lu(4b)) in high yields. Complex 4b reacts with one equivalent of cyclohexanone to give the methyl abstraction product [{(L)Lu(μ(2) -CH(3) )}(3) (μ(3) -OC(6)H(9))(μ(3)-O)] (5b), whereas reaction of 4b with acetophenone forms the insertion product [{(L)Lu(μ(2)-CH(3))}(3){μ(3)-OCPh(CH(3))(2)}(μ(3)-O)] (6b). Complex 4a is inert to ketone under the same conditions. All these new complexes have been characterized by elemental analysis, NMR spectroscopy, and confirmed by X-ray diffraction determination.     

Reactions of nickel(II) 2,21-dimethyl-2-aza-21-carbaporphyrin with phenyl Grignard reagents, phenyllithium, and n-butyllithium

Addition of a phenyl Grignard reagent to a toluene solution of the nickel(II) chloride complex of a dimethylated inverted porphyrin, (2-NCH3-21-CH3CTPP)NiIICl (1), at 203 K results in the formation of a rare paramagnetic (sigma-phenyl)nickel(II) species, (2-NCH3-21-CH3CTPP)NiIIPh (2). The coordination of the sigma-phenyl in 2 is determined by a unique pattern of three sigma-phenyl resonances (ortho 375.0 ppm; meta 108.94 ppm; para 35.68 ppm (at 283 K)) in the 1H NMR and 2H NMR spectra. The (sigma-phenyl)nickel(II) compound 2 is in the high-spin ground electronic state (dxy)2(dxz)2(dyz)2(dz2)1(dx2-y2)1, as confirmed by similarity of the NMR spectra of the equatorial ligand in 1 and 2. Titration of 1 with phenyllithium produces (2-NCH3-21-CH3CTPP)NiIIPh (2). One-electron reduction with excess PhLi yields [(2-NCH3-21-CH3CTPP)NiIIPh]- (3), which can be also generated by independent routes, e.g., by reduction of (2-NCH3-21-CH3CTPP)NiIIPh using lithium triethylborohydride or tetrabutylammonium borohydride. The spectroscopic data indicate that (2-NCH3-21-CH3CTPP)NiIIPh (2) undergoes one-electron reduction without a substantial disruption of the molecular geometry. The presence of two paramagnetic centers in 3, i.e., the high-spin nickel(II) and the carbaporphyrin anion radical, produces remarkable variations in a spectral patterns, such as the upfield and downfield positions of pyrrole resonances (103.78, 96.66, -25.35, -50.97, -92.15, -114.83 ppm (at 253 K)) and sign alternations of the meso-phenyl resonances (ortho -77.81, -79.34 ppm; meta 48.77, 48.04 ppm; para -85.65, -86.46 ppm (at 253 K)). A single species, 4, is detected in the 1H NMR titration of 1 with n-butyllithium. The formation of one- or two-electron-reduced species, [(2-NCH3-21-CH3CTPP)NiBu]- or [(2-NCH3-21-CH3CTPP)NiBu]2-, respectively, is considered to account for the spectroscopic properties of 4 (pyrrole 17.33, 15.45, -5.79, -7.74, -14.62, -58.14 ppm; 21-CH3 3 ppm (at 203 K)). The temperature dependence of the hyperfine shifts of 4 demonstrates pronounced anti-Curie behavior, interpreted in terms of a temperature-dependent spin equilibrium between diamagnetic and paramagnetic states with diamagnetic properties approached as the temperature is lowered. Warming of 2-4 results in complete decomposition via homolytic/heterolytic cleavage of an axial nickel-apical carbon bond. In the case of 2 or 3, the process yields a mixture of two compounds, 5 and 6, which are detected by EPR spectroscopy, demonstrating the anisotropy of the g tensor (5, g1 = 2.237, g2 = 2.092, g3 = 2.090; 6, g1 = 2.115, g2 = 2.030, g3 = 1.940 (in frozen toluene solution at 77 K)).     

Reactivity of Mo(PMe3)6 towards benzothiophene and selenophenes: new pathways relevant to hydrodesulfurization

Mo(PMe(3))(6) cleaves a C-S bond of benzothiophene to give (kappa(2)-CHCHC(6)H(4)S)Mo(PMe(3))(4), which rapidly isomerizes to the olefin-thiophenolate and 1-metallacyclopropene-thiophenolate complexes, (kappa(1),eta(2)-CH(2)CHC(6)H(4)S)Mo(PMe(3))(3)(eta(2)-CH(2)PMe(2)) and (kappa(1),eta(2)-CH(2)CC(6)H(4)S)Mo(PMe(3))(4). The latter two molecules result from a series of hydrogen transfers and are differentiated according to whether the termini of the organic fragments coordinate as olefin or eta(2)-vinyl ligands, respectively. The reactions between Mo(PMe(3))(6) and selenophenes proceed differently from those of the corresponding thiophenes. For example, whereas Mo(PMe(3))(6) reacts with thiophene to give eta(5)-thiophene and butadiene-thiolate complexes, (eta(5)-C(4)H(4)S)Mo(PMe(3))(3) and (eta(5)-C(4)H(5)S)Mo(PMe(3))(2)(eta(2)-CH(2)PMe(2)), selenophene affords the metallacyclopentadiene complex [(kappa(2)-C(4)H(4))Mo(PMe(3))(3)(Se)](2)[Mo(PMe(3))(4)] in which the selenium has been completely abstracted from the selenophene moiety. Likewise, in addition to (kappa(1),eta(2)-CH(2)CC(6)H(4)Se)Mo(PMe(3))(4) and (kappa(1),eta(2)-CH(2)CHC(6)H(4)Se)Mo(PMe(3))(3)(eta(2)-CH(2)PMe(2)), which are counterparts of the species observed in the benzothiophene reaction, the reaction of Mo(PMe(3))(6) with benzoselenophene yields products resulting from C-C coupling, namely [kappa(2),eta(4)-Se(C(6)H(4))(CH)(4)(C(6)H(4))Se]Mo(PMe(3))(2) and [mu-Se(C(6)H(4))(CH)C(CH)(2)(C(6)H(4))](mu-Se)[Mo(PMe(3))(2)][Mo(PMe(3))(2)H].     

Reactions of 5,6,7,8-Tetrafluoro-4-hydroxy-2H-chromen-2-ones with methylamine

5,6,7,8-Tetrafluoro-4-hydroxy-2H-chromen-2-one reacts with methylamine to give methylammonium 5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, regardless of the solvent. The reaction of 3-acetyl-5,6,7,8-tetrafluoro-4-hydroxy-2H-chromen-2-one with the same amine in ethanol or acetonitrile leads to the formation of methylammonium 3-acetyl-5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, while in dimethyl sulfoxide 5,6,8-trifluoro-7-methylamino-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is formed. The latter is also formed in the reaction of 5,6,7,8-tetrafluoro-4-hydroxy-3-(1-iminoethyl)-2H-chromen-2-one with methylamine in DMSO, whereas in ethanol and acetonitrile 5,6,7,8-tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is obtained. 5,6,7,8-Tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione reacts with methylamine, yielding 7-mono-or 5,7-bis(methylamino)-substituted derivatives.     

Enantioselective self-assembly of bimetallic [Mn(II) (delta)-Cr(III)(C2O4)3]- and [Mn(II) (lambda)-Cr(III)(C2O4)3]- layered anionic networks templated by the optically active (Rp)- and (Sp)-[1-CH2N(n-C3H7)3-2-CH3-C5H3Fe-C5H5]+ ions

The ferrocenic ammonium (Rp)- and (Sp)-[1-CH2NR(3-)-2-CH3-C5H3Fe-C5H5] iodide salts with R=CH3, C2H5, n-C3H7, n-C4H9, were synthesized starting from the (Rp)- and (Sp)-[1-CH2N(CH3)2-2-CH3-C5H3Fe-C5H5] amines obtained in their optically active forms through asymmetric cyclopalladation of [C5H5Fe-C5H4CH2N(CH3)2]. 1H NMR studies of these planar chiral 1,2-disubstituted ferrocenic ammonium iodide salts in the presence of the (Delta)-(tris(tetrachlorobenzenediolato)phosphate(V) anion), [(Delta)-Trisphat] support the formation of specific diastereomeric ion pairs. Such intermolecular interactions can be related to the self-assembly of the two-dimensional optically active compounds [[(Sp)-1-CH2N(n-C3H7)3-2-CH3-C5H3Fe-C5H5][Mn (Delta)-Cr(C2O4)3]] and [[(Rp)-1-CH2N(n-C3H7)3-2-CH3-C5H3Fe-C5H5][Mn (Lambda)-Cr(C2O4)3]] starting from the resolved (Rp)- and (Sp)-[1-CH2N(n-C3H7)3-2-CH3-C5H3Fe-C5H5]+ ion associated to the racemic anionic building block rac-[Cr(C2O4)3]3- and Mn2+. Both enantiomeric forms of the networks behave as ferromagnets with a Curie temperature of 5.7 K.     

Synthesis of some new pyrimidine selanyl derivatives

The targeted synthesis of 2-(methylsulfanyl)-6-(furan-2-yl)-4(3H)-selenoxo -pyrimidine-5-carbonitrile failed due to the formation 1-methyl-2-methylsulfanyl-6-oxo -4-(furan-2-yl)-1,6-dihydropyrimidine-5-carbonitrile. A new series of 5,6,7,8-tetrahydro-1-benzo thieno[2,3-d]pyrimidine-4-yl substituted selanyl derivatives were prepared by the reaction of sodium diselenide with 4-chloro-5,6,7,8-tetrahydro-1-benzothieno[2,3-d]pyrimidine followed by the reaction with chloroacetic acid derivatives such as ethyl chloroacetate, chloroacetamide or chloroacetonitrile. Hydrazinolysis of ethyl (5,6,7,8-tetrahydro-1-benzothieno[2,3-d]pyrimidine- 4-ylselanyl)acetate with hydrazine hydrate gave the corresponding hydrazino derivative. The latter reacted with ethyl acetoacetate, acetylacetone, diethyl malonate, ethoxymethylenemalononitrile or ethyl 2-cyano-3-ethoxyacetate to afford 5-methyl-2-[2-(5,6,7,8-tetrahydro-1-benzothieno [2,3-d]pyrimidine-4-ylselanyl)acetyl]-2,4-dihydropyrazol-3-one, 1-(3,5-dimethylpyrazol-1-yl)-2- (5,6,7,8-tetrahydro-1-benzothieno[2,3-d]pyrimidin-4-ylselanyl)ethanone, 1-[2-(5,6,7,8-tetrahydro -1-benzothieno[2,3-d]pyrimidine-4-ylselanyl)acetyl]-2,4-dihydropyrazolidine-3,5-dione and 5-Amino-1-[2-(5,6,7,8-tetrahydro-1-benzothieno[2,3-d]pyrimidin-4-ylselanyl)acetyl]-1H-pyrazol -4-yl substituted carbonitrile or ethyl carboxylate, respectively. The structure of the novel compounds was confirmed by spectroscopic tools (IR, ¹H NMR ¹³C NMR and mass spectra) and elemental analysis.     

Facile and selective aliphatic C-H bond activation at ambient temperatures initiated by Cp*W(NO)(CH2CMe3)(eta(3)-CH2CHCHMe)

Thermolysis of Cp*W(NO)(CH2CMe3)(eta(3)-CH2CHCHMe) (1) at ambient temperatures leads to the loss of neopentane and the formation of the eta(2)-diene intermediate, Cp*W(NO)(eta(2)-CH2=CHCH=CH2) (A), which has been isolated as its 18e PMe3 adduct. In the presence of linear alkanes, A effects C-H activations of the hydrocarbons exclusively at their terminal carbons and forms 18e Cp*W(NO)(n-alkyl)(eta(3)-CH2CHCHMe) complexes. Similarly, treatments of 1 with methylcyclohexane, chloropentane, diethyl ether, and triethylamine all lead to the corresponding terminal C-H activation products. Furthermore, a judicious choice of solvents permits the C-H activation of gaseous hydrocarbons (i.e., propane, ethane, and methane) at ambient temperatures under moderately elevated pressures. However, reactions between intermediate A and cyclohexene, acetone, 3-pentanone, and 2-butyne lead to coupling between the eta(2)-diene ligand and the site of unsaturation on the organic molecule. For example, Cp*W(NO)(eta(3),eta(1)-CH2CHCHCH2C(CH2CH3)2O) is formed exclusively in 3-pentanone. When the site of unsaturation is sufficiently sterically hindered, as in the case of 2,3-dimethyl-2-butene, C-H activation again becomes dominant, and so the C-H activation product, Cp*W(NO)(eta(1)-CH2CMe=CMe2)(eta(3)-CH2CHCHMe), is formed exclusively from the alkene and 1. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by X-ray crystallographic analyses. Finally, the newly formed alkyl ligands may be liberated from the tungsten centers in the product complexes by treatment with iodine. Thus, exposure of a CDCl3 solution of the n-pentyl allyl complex, Cp*W(NO)(n-C5H11)(eta(3)-CH2CHCHMe), to I2 at -60 degrees C produces n-C5H11I in moderate yields.     

Influence of the boron atom on the solvatochromic properties of 4-nitroaniline-functionalized boronate esters

Para-nitroaniline derivatives with peripheral 1,2- and 1,3-diol functionalities [O(2)N-C(6)H(4)-NR(1)-CH(2)CH(OH)CH(2)OH; O(2)N-C(6)H(4)-NR(1)-CH(CH(2)OH)(2); R(1) = -H, -CH(3)] covalently bonded to the amino group are esterified with various para-substituted phenylboronic acids [R(2)-C(6)H(4)-B(OH)(2); R(2) = -OCH(3), -CH(3), -H, -Br, -CHO, -NO(2), -B(OH)(2)], and the solvatochromic properties of these esters are investigated in 33 solvents of different polarity. To interpret the solvent effects, the established linear solvation energy (LSE) multiparameter equations of Kamlet-Taft and the improved Catalán scales are used. Although the boron atom is separated by two or three sp(3)-hybridized carbon atoms from the actual chromophore, solvation effects have a significant positive solvatochromic effect on the nitroaniline unit (R(1) = -CH(3)) as result of the solvent acting as a donor at the boron atom. The influence of the substituent R(2) on the coefficient b of the LSE relationship according to Kamlet-Taft and Catalán, which reflects the quantitative influence of the hydrogen-bonding acceptor or the electron-pair donor capacity of the solvent on the position of the UV-vis absorption maximum, can be determined via a linear Hammett relationship [b = f(σ(p))]. The interpretation of the effects is based on the electronic influence of the solvated boronic acid ester unit on the 4-nitroaniline group, predominantly through inductive interactions.     

Syntheses and structural and electrochemical characterizations of vanadatricarbadecaboranyl analogues of vanadocene and the structural characterization of the [Li(CH(3)CN)2+](6-CH(3)-nido-5,6,9-C(3)B(7)H(9-) tricarbadecaboranyl anion.

A single-crystal X-ray determination of the [Li(CH(3)CN)(2)(+)](6-CH(3)-nido-5,6,9-C(3)B(7)H(9)(-)) salt has shown that the 6-CH(3)-nido-5,6,9-C(3)B(7)H(9)(-) tricarbadecaboranyl anion has a nido-cage geometry based on an octadecahedron missing the unique six-coordinate vertex. The resulting six-membered open face is puckered, with two of the cage carbons (C6 and C9) occupying the low-coordinate cage positions above the plane of the four remaining atoms (C5, B7, B8, and B10). The Li(+) ion is centered over the open face and is solvated by two acetonitrile molecules. The reactions of the 6-CH(3)-nido-5,6,9-C(3)B(7)H(9)(-) anion with various vanadium halide salts, including VCl(4), VCl(3), and VBr(2), each resulted in the isolation of the same five paramagnetic products (2-6) of composition V(CH(3)-C(3)B(7)H(9))(2). X-ray crystallographic determinations of 2-5 showed that the complexes consist of two octadecahedral VC(3)B(7) fragments sharing a common vanadium vertex and established their structures as commo-V-(1-V-4'-CH(3)-2',3',4'-C(3)B(7)H(9))(1-V-2-CH(3)-2,3,4-C(3)B(7)H(9)) (2), commo-V-(1-V-5'-CH(3)-2',3',5'-C(3)B(7)H(9))(1-V-4-CH(3)-2,3,4-C(3)B(7)H(9)) (3), commo-V-(1-V-5'-CH(3)-2',3',5'-C(3)B(7)H(9))(1-V-2-CH(3)-2,3,4-C(3)B(7)H(9)) (4), and commo-V-(1-V-2-CH(3)-2,3,4-C(3)B(7)H(9))(2) (5). These complexes can be considered as tricarbadecaboranyl analogues of vanadocene, (eta(5)-C(5)H(5))(2)V. However, unlike vanadocene, these complexes are air- and moisture-stable and have only one unpaired electron. The five complexes differ with respect to one another in that they either (1) contain different enantiomeric forms of the CH(3)-C(3)B(7)H(9) cages, (2) have a different twist orientation of the two cages, or (3) have the methyl group of the CH(3)-C(3)B(7)H(9) cage located in either the 2 or 4 position of the cage. Subsequent attempts to oxidize the compounds with reagents such as Br(2) and Ag(+) were unsuccessful, illustrating the ability of the tricarbadecaboranyl anion to stabilize metals in low oxidation states. Consistent with this, both the electrochemical oxidation and the reduction of 2 were much more positive than those of the same oxidation state changes in vanadocene. The one-electron reduction of 2 is a remarkable 2.9 V positive of that of Cp(2)V.     

New iridacyclohexadienes and iridabenzenes by [2+2+1] cyclotrimerization of alkynes and facile interconversion between iridacyclohexadienes and iridabenzenes

Iridabenzenes [Ir[=CHCH=CHCH=C(CH2R)](CH3CN)2(PPh3)2]2+ (R=Ph 4 a, R=p-C6H4CH3 4 b) are obtained from the reactions of H+ with iridacyclohexadienes [Ir[-CH=CHCH=CHC(=CH-p-C6H4R')](CO)(PPh3)2]+ (R'=H 3 a, R'=CH3 3 b), which are prepared from [2+2+1] cyclotrimerization of alkynes in the reactions of [Ir(CH3CN)(CO)(PPh3)2]+ with HC[triple chemical bond]CH and HC[triple chemical bond]CR. Iridabenzenes 4 react with CO and CH3CN in the presence of NEt3 to give iridacyclohexadienes [Ir[-CH=CHCH=CHC(=CHR)](CO)2(PPh3)2]+ (6) and [Ir[-CH=CHCH=CHC(=CHR)](CH3CN)2(PPh3)2]+ (7), respectively. Iridacyclohexadienes 6 and 7 also convert to iridabenzenes 4 by the reactions with H+ in the presence of CH3CN. Alkynyl iridacyclohexadienes [Ir[-CH=CHCH=CHC(=CH-p-C6H4R')](-C[triple chemical bond]CH)(PPh3)2] (8) undergo a cleavage of C[triple chemical bond]C bond by H+/H2O to produce [Ir[-CH=CHCH=CHC(=CH-p-C6H4R')](-CH3)(CO)(PPh3)2] (10) via facile inter-conversion between iridacyclohexadienes and iridabenzenes.     

Aluminum compounds containing eta1- and/or eta5-bidentate dianionic pyrrolyl-methylamide ligands

A series of dialuminum compounds have been synthesized and their reactivity and application for lactide polymerization have been studied. The reaction of AlH3 x NMe3 with [C4H3NH(2-CH2NHtBu)] in diethyl ether generated a dimeric aluminum hydride compound, [[[C4H3N(2-CH2NtBu)]AlH]2] (1). The structure of 1 was confirmed by spectroscopy of a deuterated analogue of 1 with an Al--D function. Direct treatment of [C4H3NH(2-CH2NHtBu)] with LiAlH4 in diethyl ether resulted in colorless crystals of [[Li[micro-eta1:eta5-C4H3N(2-CH2NtBu)]2Al]2] (2) in 80 % yield after recrystallization from a toluene solution. The micro-eta1:eta5-pyrrolyl protons exhibit high-field shifts at delta=5.73, 6.15, and 6.72 comparable to a similar eta5-bonding mode in the literature. Treatment of 1 with 1 equiv acetone oxime or acetone in dichloromethane gave [[[C4H3N(2-CH2NtBu)]Al[varkappaO,varkappaN-(ON==CMe2)]]2] (3) and [[[C4H3N(2-CH2NtBu)]Al(O--CHMe2)]2] (4) in 67 % and 60 % yield, respectively. Compounds 1-4 have been characterized by X-ray diffractometry and were used as catalysts for epsilon-caprolactone polymerization.