TiCl4-n-Bu4NX (X = I, Br, and Cl) combination-induced coupling of alpha,beta-unsaturated ketones with aldehydes.

A three-component coupling reaction between vinyl ketones, aldehydes, and halides has been developed with TiCl(4)-n-Bu(4)NX combined reagents. Treatment of vinyl ketones with a TiCl(4)-n-Bu(4)NI combination followed by an addition of a variety of aldehydes provides syn-alpha-iodomethyl-beta-hydroxy ketones with high stereoselectivity. Methyltriphenylphosphonium iodide as well as n-Bu(4)NI acts efficiently as a halide source. The combination of TiCl(4)-n-Bu(4)NBr provides the corresponding bromo compounds in good yields. syn-alpha-Chloromethyl-beta-hydroxy ketones are obtained with the TiCl(4)-n-Bu(4)NCl combination. A competitive experiment reveals that the order of relative reactivity of the combinations is TiCl(4)-n-Bu(4)NI > TiCl(4)-n-Bu(4)NBr > TiCl(4)-n-Bu(4)NCl.     

A mild conversion of phenylpropropnoid into rare phenylbutanoids: (E)-4-(2,4,5-trimethoxyphenyl)but-1,3-diene and (E)-4-(2,4,5-trimethozypheny)but-1-ene occuring in Zingiber cassumunar

(E)-4-(2',4',5'-trimethoxyphenyl)but-1,3-diene (4) and (E)-4-(2',4',5'-trimethoxyphenyl)but-1-ene (6), bioactive phenylbutanoids of Zingiber cassumunar, were synthesized exclusively with trans geometry. Treatment of methylmagnesium iodide with (E)-2',4',5'-trimethoxycinnamaldehyde (2), an oxidized product of abundantly available toxic (Z)-phenylpropanoid (1) of Acorus calamus, gave (E)-4-(2',4',5'-trimethoxyphenyl)but-3-en-2-ol (3) which upon dehydration with copper sulphate/silica gel under microwave irradiation for 3 min afforded 4 in 58% yield. Further, catalytic hydrogenation of 4 with 10% Pd/C afforded 4-(2',4',5'-trimethoxyphenyl)butane (5) which upon dehydrogenation with DDQ/SiO2 afforded hypolipidemic 6 in 54% yield.     

Synthesis and reactions of 4-(arylhydrazino)coumarins

The interaction of 4-hydroxycoumarin with phenyl-, 2-chlorophenyl- and 4-bromophenyhydrazine hydrochlorides in the presence of triethylamine led in all cases to the corresponding 4-(arylhydrazino)-coumarins and 1-aryl-3-(2-hydroxyphenyl)-2H-pyrazolin-5-ones. 4-(Arylhydrazino)coumarins reacted with 4-chlorobenzaldehyde in the presence of piperidine acetate to give the corresponding 2-aryl-3-(4-chlorophenyl)[1]benzopyrano[4,3-b]pyrazol-4-ones. The reaction of 4-(4-bromophenylhydrazino)-coumarin with 4-chlorobenzaldehyde in the presence of piperidine acetate and an excess of piperidine gave 2-(4-bromophenyl)-5-(4-chlorophenyl)-3-(2-hydroxyphenyl)-4-(piperidinocarbonyl)pyrazole, but the reaction of phenyl- and 4-(2-chlorophenylhydrazino)coumarins with 4-chlorobenzaldehyde gave 1-aryl-5-(4-chlorophenyl)-3-(2-hydroxyphenyl)-4-(1-piperidino)carbonyl-4,5-dihydropyrazoles.     

Tetranuclear [Rh4(mu-PyS2)2(diolefin)4] complexes as building blocks for new inorganic architectures: synthesis of coordination polymers and heteropolynuclear complexes with electrophilic d8 and d10 metal fragments

The reaction of [Rh4(mu-PyS2)2(cod)4] (PyS2 = 2,6-pyridinedithiolate, cod = 1,5-cyclooctadiene) with CF3SO3Me gave the cationic complex [Rh(4)(mu-PyS(2)Me)(2)(cod)4][CF3SO3]2 (1) with two 6-(thiomethyl)pyridine-2-thiolate bridging ligands from the attack of Me+ at the terminal sulfur atoms of the starting material. Under identical conditions [Rh4(mu-PyS2)2(tfbb)4] (tfbb = tetrafluorobenzobarrelene) reacted with CF3SO3Me to give the mixed-ligand complex [Rh(4)(mu-PyS2)(mu-PyS2Me)(tfbb)4][CF3SO3] 2. The nucleophilicity of the bridging ligands in the complexes [Rh4(mu-PyS2)2(diolefin)4] was exploited to prepare heteropolynuclear species. Reactions with [Au(PPh3)(Me2CO)][ClO4] gave the hexanuclear complexes [(PPh3)2Au2Rh4(mu-PyS2)2(diolefin)4][ClO4]2 (diolefin = cod (3), tfbb (4)). The structure of 4, solved by X-ray diffraction methods, showed the coordination of the [Au(PPh3)]+ fragments to the peripheral sulfur atoms in [Rh4(mu-PyS2)2(diolefin)4] along with their interaction with the neighbor rhodium atoms. Neutral coordination polymers of formula [ClMRh4(mu-PyS2)2(diolefin)4]n (M = Cu (5, 6), Au (7)) result from the self-assembly of alternating [Rh4(mu-PyS2)2(diolefin)4] ([Rh4]) blocks and MCl linkers. The formation of the infinite polymetallic chains was found to be chiroselective for M = Cu; one particular chain contains exclusively homochiral [Rh4] complexes. Cationic heterometallic coordination polymers of formula [MRh4(mu-PyS2)2(diolefin)4]n[BF4]n (M = Ag (8, 9), Cu (10, 11)) and [Rh5(mu-PyS2)2(diolefin)5]n[BF4]n (12, 13) result from the reactions of [Rh4] with [Cu(CH2CN)4]BF4, AgBF4, and [Rh(diolefin)(Me2CO)2]BF4, respectively. The heterometallic coordination polymers exhibit a weak electric conductivity in the solid state in the range (1.2-2.8) x 10(-7) S cm(-1).     

High-level ab initio predictions for the ionization energies and heats of formation of five-membered-ring molecules: thiophene, furan, pyrrole, 1,3-cyclopentadiene, and borole, C4H4X/C4H4X+ (X = S, O, NH, CH2, and BH)

The ionization energies (IEs) and heats of formation (ΔH°(f0)/ΔH°(f298)) for thiophene (C(4)H(4)S), furan (C(4)H(4)O), pyrrole (C(4)H(4)NH), 1,3-cyclopentadiene (C(4)H(4)CH(2)), and borole (C(4)H(4)BH) have been calculated by the wave function-based ab initio CCSD(T)/CBS approach, which involves the approximation to the complete basis set (CBS) limit at the coupled-cluster level with single and double excitations plus a quasi-perturbative triple excitation [CCSD(T)]. Where appropriate, the zero-point vibrational energy correction (ZPVE), the core-valence electronic correction (CV), and the scalar relativistic effect (SR) are included in these calculations. The respective CCSD(T)/CBS predictions for C(4)H(4)S, C(4)H(4)O, C(4)H(4)NH, and C(4)H(4)CH(2), being 8.888, 8.897, 8.222, and 8.582 eV, are in excellent agreement with the experimental values obtained from previous photoelectron and photoion measurements. The ΔH°(f0)/ΔH°(f298) values for the aforementioned molecules and their corresponding cations have also been predicted by the CCSD(T)/CBS method, and the results are compared with the available experimental data. The comparisons between the CCSD(T)/CBS predictions and the experimental values for C(4)H(4)S, C(4)H(4)O, C(4)H(4)NH, and C(4)H(4)CH(2) suggest that the CCSD(T)/CBS procedure is capable of predicting reliable IE values for five-membered-ring molecules with an uncertainty of ±13 meV. In view of the excellent agreements between the CCSD(T)/CBS predictions and the experimental values for C(4)H(4)S, C(4)H(4)O, C(4)H(4)NH, and C(4)H(4)CH(2), the similar CCSD(T)/CBS IE and ΔH°(f0)/ΔH°(f298) predictions for C(4)H(4)BH, whose thermochemical data are not readily available due to its reactive nature, should constitute a reliable data set. The CCSD(T)/CBS IE(C(4)H(4)BH) value is 8.868 eV, and ΔH°(f0)/ΔH°(f298) values for C(4)H(4)BH and C(4)H(4)BH(+) are 269.5/258.6 and 1125.1/1114.6 kJ/mol, respectively. The highest occupied molecular orbitals (HOMO) of C(4)H(4)S, C(4)H(4)O, C(4)H(4)NH, C(4)H(4)CH(2), and C(4)H(4)BH have also been studied by the natural bond orbital (NBO) method, and the extent of π-electron delocalization in these five-membered rings are discussed in correlation with their molecular structures and orbitals.     

Palladacycles of novel bisoxazoline chelating ligands based on the dimeric cyclobutadiene linked cobalt sandwich compound [(η5-Cp)Co(η4-C4Ph3)]2

The reaction of 1,4-diphenylbutadiyne along with diphenylacetylene, when carried out with η(5)-[MeOC(O)Cp]Co(PPh(3))(2) resulted in the cyclobutadiene linked dimeric cobalt sandwich compound {[η(5)-MeOC(O)Cp]Co(η(4)-C(4)Ph(3))}(2) (1) along with the known monomeric compound η(5)-[MeOC(O)Cp]Co(η(4)-C(4)Ph(4)). Compound 1, on treatment with KOH gave the dicarboxylic acid {η(5)-[HOC(O)Cp]Co(η(4)-C(4)Ph(3))}(2) (2) which on reaction with oxalyl chloride followed by (S)-2-amino-3-methyl-1-butanol, triethylamine and mesylchloride was converted to the bis(cobalt oxazoline) based chiral ligand {[η(5)-(4-iPr-2-Ox)Cp]Co(η(4)-C(4)Ph(3))}(2) (3) (Ox = Oxazolinyl). Compound 3 on reaction with palladium acetate gave an NCN bound bis(cobalt-oxazolinyl) palladacycle {[η(5)-(4-iPr-2-Ox)Cp]Co(η(4)-C(4)Ph(3))}(2)PdOAc (4) having both the oxazolinyl groups bound to the palladium in a chelate mode and one of the Cp rings forming a five membered [C,N] palladacycle. Reaction of 4 with aq. NaCl resulted in the chloro analogue of 4, {[η(5)-(4-iPr-2-Ox)Cp]Co(η(4)-C(4)Ph(3))}(2)PdCl (5). A nonchiral bidentate bis cobalt oxazoline ligand {[η(5)-(Ox)Cp]Co(η(4)-C(4)Ph(3))}(2) (6) was also prepared by replacing (S)-2-amino-3-methyl-1-butanol with 2-amino-1-ethanol in the procedure used for the preparation of 3. A reaction of 1,4-diphenylbutadiyne, diphenylacetylene and (η(5)-Cp)Co(PPh(3))(2) resulted in the dimer [(η(5)-Cp)Co(η(4)-C(4)Ph(3))](2) (7) and small amounts of a trimer [(η(5)-Cp)Co(η(4)-C(4)Ph(3))](2)[(η(5)-Cp)Co(η(4)-C(4)Ph(2))] (8) having no substituents on the Cp rings. All the compounds except 2 were structurally characterized. Structural studies on palladacycles 4 and 5 showed interesting anagostic C-H···Pd interactions between the ortho hydrogen of one of the Cp rings and the palladium centre. Preliminary studies carried out on the palladacycles showed promising catalytic activity in the asymmetric rearrangement of trichloroacetimidates.     

Hexasubstituted donor-acceptor benzenes as nonlinear optically active molecules with multiple charge-transfer transitions

The synthesis of three novel nonlinear optical (NLO) chromophores with threefold symmetry, namely 1,3,5-tris(4-N,N-diethylaminophenyl)-2,4,6-tris(4-nitrophenyl)benzene (3), 1,3,5-tris(4-N,N-dihexylaminophenylbutadiynyl)-2,4,6-tris(4-nitrophenyl)benzene (13) and 1,3,5-tris(4-N,N-dihexylaminophenylethynyl)-2,4,6-tris(4-nitrophenylethynyl)benzene (4 b), is reported. We used the [Co(2)(CO)(8)]-catalysed trimerisation of 4-N,N-diethylamino-4'-nitrotolane (5) to prepare 3. The trimerisation experiment carried out with 1-(4-N,N-diethylaminophenyl)-6-(4-N,N-nitrophenyl)hexatriyne (6) and [Rh(PPh(3))(3)Cl] afforded 13. A stepwise approach was used to prepare 4 b. 1,3,5-Trichloro-2,4,6-triiodobenzene (8 b) was coupled with 4-nitrophenyl-acetylene (14) under Pd(0) catalysis to yield 1,3,5-trichloro-2,4,6-tris(4-nitrophenylethynyl)benzene (15). The coupling reaction of 15 with 4-N,N-dihexylaminophenylethynyltributylstannane (21) led to 4 b. X-ray investigations on 3, 4 b and 13 confirmed the structural assignments and revealed that the peripheral aryl rings in 4 b are less twisted around the connecting bonds than in 3 and 13. A large second-order polarisability (beta) of 4 b relative to 3 and 13 was determined by hyper-Rayleigh scattering (HRS). Compound 4 b represents an NLO chromophore with second-order polarisabily among the highest obtained so far for two-dimensional nondipolar NLO chromophores.     

Synthesis and characterization of octa- and hexanuclear polyoxomolybdate wheels: role of the inorganic template and of the counterion

Eight new compounds based on [O3PCH2PO3]4- ligands and {MoV2O4} dimeric units have been synthesized and structurally characterized. Octanuclear wheels encapsulating various guests have been isolated with different counterions. With NH4+, a single wheel was obtained, as expected, with the planar CO32- guest, (NH4)12[(MoV2O4)4(O3PCH2PO3)4(CO3)2].24H2O (1a), while with the pyramidal SO32- guest, only the syn isomer (NH4)12[(MoV2O4)4(O3PCH2PO3)4(SO3)2].26H2O (2a) was characterized. The corresponding anti isomer was obtained with Na+ as counterions, Na12[(MoV2O4)4(O3PCH2PO3)4(SO3)2]39H2O (2b), and with mixed Na+ and NH4(+) counterions, Na+(NH4)11[(MoV2O4)4(O3PCH2PO3)4(SO3)2].13H2O (2d). With [O3PCH2PO3]4- extra ligands, the octanuclear wheel Li12(NH4)2[(MoV2O4)4(O3PCH2PO3)4(HO3PCH2PO3)2].31H2O (4a) was isolated with Li+ and NH4+ counterions and Li14[(MoV2O4)4(O3PCH2PO3)4(HO3PCH2PO3)2].34H2O (4c) as a pure Li+ salt. A new rectangular anion, formed by connecting two MoV dimers and two MoVI octahedra via methylenediphosphonato ligands with NH4+ as counterions, (NH4)10[(MoV2O4)2(MoVIO3)2(O3PCH2PO3)2(HO3PCH2PO3)2].15H2)O (3a), and Li9(NH4)2Cl[(MoV2O4)2(MoVIO3)2(O3PCH2PO3)2]. 22H2O (3d) as a mixed NH4+ and Li+ salt have also been synthesized. The structural characterization of the compounds, combined with a study of their behavior in solution, investigated by 31P NMR, has allowed a discussion on the influence of the counterions on the structure of the anions and their stability. Density functional theory calculations carried out on both isomers of the [(MoV2O4)4(O3PCH2PO3)4(SO3)2]12- anion (2), either assumed isolated or embedded in a continuum solvent model, suggest that the anti form is favored by approximately 2 kcal mol(-1). Explicit insertion of two solvated counterions in the molecular cavity reverses this energy difference and reduces it to less than 1 kcal mol(-1), therefore accounting for the observed structural versatility.     

Copper halide-bridged ruthenium telluride carbonyl complexes: discovery of the semiconducting cluster chain polymer {[PPh4]2[Te2Ru4(CO)10Cu4Br2Cl2].THF}infinity

A new series of Te-Ru-Cu carbonyl complexes was prepared by the reaction of K(2)TeO(3) with [Ru(3)(CO)(12)] in MeOH followed by treatment with PPh(4)X (X=Br, Cl) and [Cu(MeCN)(4)]BF(4) or CuX (X=Br, Cl) in MeCN. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was first treated with PPh(4)X followed by the addition of [Cu(MeCN)(4)]BF(4), doubly CuX-bridged Te(2)Ru(4)-based octahedral clusters [PPh(4)](2)[Te(2)Ru(4)(CO)(10)Cu(2)X(2)] (X=Br, [PPh(4)](2)[1]; X=Cl, [PPh(4)](2)[2]) were obtained. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)X (X=Br, Cl) followed by the addition of CuX (X=Br, Cl), three different types of CuX-bridged Te-Ru carbonyl clusters were obtained. While the addition of PPh(4)Br or PPh(4)Cl followed by CuBr produced the doubly CuBr-bridged cluster 1, the addition of PPh(4)Cl followed by CuCl led to the formation of the Cu(4)Cl(2)-bridged bis-TeRu(5)-based octahedral cluster compound [PPh(4)](2)[{TeRu(5)(CO)(14)}(2)Cu(4)Cl(2)] ([PPh(4)](2)[3]). On the other hand, when the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)Br followed by the addition of CuCl, the Cu(Br)CuCl-bridged Te(2)Ru(4)-based octahedral cluster chain polymer {[PPh(4)](2)(Te(2)Ru(4)(CO)(10)Cu(4)Br(2)Cl(2)).THF}(infinity) ({[PPh(4)](2)[4].THF}(infinity)) was produced. The chain polymer {[PPh(4)](2)[4].THF}(infinity) is the first ternary Te-Ru-Cu cluster and shows semiconducting behavior with a small energy gap of about 0.37 eV. It can be rationalized as resulting from aggregation of doubly CuX-bridged clusters 1 and 2 with two equivalents of CuCl or CuBr, respectively. The nature of clusters 1-4 and the formation and semiconducting properties of the polymer of 4 were further examined by molecular orbital calculations at the B3LYP level of density functional theory.     

Ba2AgInS4 and Ba4MGa5Se12 (M = Ag, Li): syntheses, structures, and optical properties

The first two members in alkaline-earth/group XI/group XIII/chalcogen system, namely Ba(2)AgInS(4) and Ba(4)AgGa(5)Se(12), were synthesized along with a Li analogue Ba(4)LiGa(5)Se(12). Ba(2)AgInS(4) crystallizes in space group P2(1)/c. It contains [AgInS(4)](4-) layers built from AgS(3) triangles and InS(4) tetrahedra with Ba(2+) cations inserted between the layers. Ba(4)AgGa(5)Se(12) and Ba(4)LiGa(5)Se(12) adopt two closely-related structure types in space group P4[combining macron]2(1)c with structural difference originating from the different positions of Ag and Li in them. The three-dimensional framework in Ba(4)AgGa(5)Se(12) is composed of GaSe(4) tetrahedra with the Ba and Ag atoms occupying the large and small channels respectively, whereas that in Ba(4)LiGa(5)Se(12) is built from LiSe(4) and GaSe(4) tetrahedra with channels to accommodate the Ba atoms. As deduced from the diffuse reflectance spectra measurement, the optical band gaps were 2.32 (2) eV, 2.52 (2) eV, and 2.65 (2) eV for Ba(2)AgInS(4), Ba(4)AgGa(5)Se(12), and Ba(4)LiGa(5)Se(12), respectively.     

Luminescent heteronuclear Au(I)5Ag(I)8 complexes of [1,2,3-C6(C6H4R-4)3]3- (R = H, CH3, But) by cyclotrimerization of arylacetylides

Unusual AuI-AgI heterometallic complexes [Au5Ag8(mu-dppm)4{1,2,3-C6(C6H4R-4)3}(CCC6H4R-4)7]3+ (R = H 1, CH3 2, But 3) were isolated by reactions of polymeric silver arylacetylides (AgCCC6H4R-4)n with binuclear gold component [Au2(mu-dppm)2(MeCN)2]2+ (dppm = bis(diphenylphosphino)methane), in which cyclotrimerization of arylacetylide -CCC6H4R-4 affords trianion {1,2,3-C6(C6H4R-4)3}3- with an unprecedented mu5-bonding mode. Compounds 1(SbF6)3-3(SbF6)3 exhibit intense photoluminescence derived from an MLCT (Au5Ag8 --> CCC6H4R-4) transition, mixed with a metal cluster-centered excited states.     

Different transmetallation behaviour of [M(P4HR4)] salts toward rhodium(I) and copper(I) (M = Na, K; R = Ph, Mes; Mes = 2,4,6-Me3C6H2)

[K(2)(P(4)Mes(4))] (1) or [Na(2)(THF)(4)(P(4)Mes(4))] (2) (Mes = 2,4,6-Me(3)C(6)H(2)) reacts with one equivalent of HCl and subsequently with 0.5 equivalents of [{RhCl(cod)}(2)] (cod = 1,5-cyclooctadiene) to give a mixture of rhodium complexes, from which [Rh(P(4)HMes(4))(cod)] (3) and the secondary product [Rh(2)(micro-P(2)HMes(2))(mu-PHMes)(cod)(2)] (4) were isolated and characterised by X-ray diffraction studies. Alternatively, the reaction of [K(2)(P(4)Ph(4))] (5) or [Na(2)(THF)(5)(P(4)Ph(4))] (6) with one equivalent of HCl and subsequently with one equivalent of [CuCl(PCyp(3))(2)] (Cyp = cyclo-C(5)H(9)) gave the complex [Cu(4)(P(4)Ph(4))(2)(PH(2)Ph)(2)(PCyp(3))(2)] (7), presumably via disproportionation of the monoanion (P(4)HPh(4))(-).     

Stabilization of reduced molybdenum-iron-sulfur single- and double-cubane clusters by cyanide ligation

Recent work has shown that cyanide ligation increases the redox potentials of Fe(4)S(4) clusters, enabling the isolation of [Fe(4)S(4)(CN)4]4-, the first synthetic Fe(4)S(4) cluster obtained in the all-ferrous oxidation state (Scott, T. A.; Berlinguette, C. P.; Holm, R. H.; Zhou, H.-C. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 9741). The generality of reduced cluster stabilization has been examined with MoFe(3)S(4) clusters. Reaction of single-cubane [(Tp)MoFe(3)S(4)(PEt(3))3]1+ and edge-bridged double-cubane [(Tp)2Mo(2)Fe(6)S(8)(PEt(3))4] with cyanide in acetonitrile affords [(Tp)MoFe(3)S(4)(CN)3]2- (2) and [(Tp)2Mo(2)Fe(6)S(8)(CN)4]4- (5), respectively. Reduction of 2 with KC(14)H(10) yields [(Tp)MoFe(3)S(4)(CN)3]3- (3). Clusters were isolated in approximately 70-90% yields as Et(4)N+ or Bu(4)N+ salts; clusters 3 and 5 contain all-ferrous cores, and 3 is the first [MoFe(3)S(4)]1+ cluster isolated in substance. The structures of 2 and 3 are very similar; the volume of the reduced cluster core is slightly larger (2.5%), a usual effect upon reduction of cubane-type Fe(4)S(4) and MFe(3)S(4) clusters. Redox potentials and 57Fe isomer shifts of [(Tp)MoFe(3)S(4)L3]2-,3- and [(Tp)2Mo(2)Fe(6)S(8)L(4)]4-,3- clusters with L = CN-, PhS-, halide, and PEt3 are compared. Clusters with pi-donor ligands (L = halide, PhS) exhibit larger isomer shifts and lower (more negative) redox potentials, while pi-acceptor ligands (L = CN, PEt3) induce smaller isomer shifts and higher (less-negative) redox potentials. When the potentials of 3/2 and [(Tp)MoFe(3)S(4)(SPh)3]3-/2- are compared, cyanide stabilizes 3 by 270 mV versus the reduced thiolate cluster, commensurate with the 310 mV stabilization of [Fe(4)S(4)(CN)4]4- versus [Fe(4)S(4)(SPh)4]4- where four ligands differ. These results demonstrate the efficacy of cyanide stabilization of lower cluster oxidation states. (Tp = hydrotris(pyrazolyl)borate(1-)).     

Reactions of tetrafluoroethene oligomers. Part 5. Some reactions of perfluoro-[(1-ethyl-1-methylpropyl)(1-methylpropyl)] keten

The title keten (1) was treated with some alcohols and amines: methanol afforded an inseparable mixture of two products, 4H-4-methoxycarbonyl-docosafluoro-3,5-dimethyl-3-ethylheptane (2) and 4-methoxycarbonyl-heneicosafluoro-3,5-dimethyl-8-ethylhept-3-ene (3). Treatment of the mixture with sodium hydroxide afforded pure (3). Reaction of (1) with benzyl alcohol yielded 4-benzyloxycarbonyl-4H-docosafluoro-3,5-dimethyl-3-ethylheptane (4) which on hydrogenation gave a mixture of 4H-heneicosafluoro-3,5-dimethyl-5-ethylhept-3-ene (5) and 4H-docosafluoro-3,5-dimethyl-3-ethyl-heptane-4-carboxylic acid (6). Reaction of (1) with ammonia yielded 4-carbonamido-heneicosafluoro-3,5-dimethyl-5-ethylhept-3-ene (7) and dimethylamine similarly afforded the N,N-dimethyl analogue (9). However, reaction of (1) with ethylamine gave an unusual cyclisation product, 1-ethyl-3H-heneicosafluoro-4-ethyl-4-methyl-3(1-ethyl-1-methylpropyl)azetan-2-one (8).     

Oxidation of heterocyclic nitrogen ylids to nitro heterocycles. Comparison of dimethyldioxirane with peracids

Oxidation of 3-amino-4-(4-chlorophenyl)furazan ( 1 ) and its phosphine imine derivative, 3-(4-chlorophenyl)-4-trioctylphosphiniminofurazan ( 3 ), with dimethyldioxirane (DMD) gave 3-(4-chlorophenyl)-4-nitrofurazan ( 4 ) as the exclusive product. However, the sulfilimine derivative, 3-(4-chlorophenyl)-4-dimethylsulfiliminofurazan ( 2 ), was converted by DMD to the sulfoximine, 3-(4-chlorophenyl)-4-dimethylsulfoximinofurazan ( 6 ). These results contrast dramatically with the oxidations of these compounds with peracids.     

Syntheses and structures of mono-, di- and tetranuclear rhodium or iridium complexes of thiacalix[4]arene derivatives

The reactions of [Cp*MCl2]2(Cp*=eta5-C5Me5, M = Rh, Ir) with thiacalix[4]arene (TC4A(OH)4) and tetramercaptothiacalix[4]arene (TC4A(SH)4) gave the mononuclear complexes [(Cp*M){eta3-TC4A(OH)2(O)2}] and the dinuclear complexes [(Cp*M)2{eta3eta3-TC4A(S)4}] respectively, while the analogous reactions with dimercaptothiacalix[4]arene (TC4A(OH)2(SH)2) produced the tetranuclear complexes [(Cp*M)2(Cp*MCl2)2-{eta3eta3eta1eta1-TC4A(O)2(S)2}].     

The first acetimino complexes of Rh(III). 4-imino-2-methylpentan-2-amino-Rh(III) complexes through metal-assisted intramolecular aldol-type condensation of two acetimino ligands

[Rh(Cp)Cl(mu-Cl)](2) (Cp = pentamethylcyclopentadienyl) reacts (i) with [Au(NH=CMe(2))(PPh(3))]ClO(4) (1:2) to give [Rh(Cp)(mu-Cl)(NH=CMe(2))](2)(ClO(4))(2) (1), which in turn reacts with PPh(3) (1:2) to give [Rh(Cp)Cl(NH=CMe(2))(PPh(3))]ClO(4) (2), and (ii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:2 or 1:4) to give [Rh(Cp)Cl(NH=CMe(2))(2)]ClO(4) (3) or [Rh(Cp)(NH=CMe(2))(3)](ClO(4))(2).H(2)O (4.H(2)O), respectively. Complex 3 reacts (i) with XyNC (1:1, Xy = 2,6-dimethylphenyl) to give [Rh(Cp)Cl(NH=CMe(2))(CNXy)]ClO(4) (5), (ii) with Tl(acac) (1:1, acacH = acetylacetone) or with [Au(acac)(PPh(3))] (1:1) to give [Rh(Cp)(acac)(NH=CMe(2))]ClO(4) (6), (iii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:1) to give 4, and (iv) with (PPN)Cl (1:1, PPN = Ph(3)P=N=PPh(3)) to give [Rh(Cp)Cl(imam)]Cl (7.Cl), which contains the imam ligand (N,N-NH=C(Me)CH(2)C(Me)(2)NH(2) = 4-imino-2-methylpentan-2-amino) that results from the intramolecular aldol-type condensation of the two acetimino ligands. The homologous perchlorate salt (7.ClO(4)) can be prepared from 7.Cl and AgClO(4) (1:1), by treating 3 with a catalytic amount of Ph(2)C=NH, in an atmosphere of CO, or by reacting 4with (PPN)Cl (1:1). The reactions of 7.ClO(4) with AgClO(4) and PTo(3) (1:1:1, To = C(6)H(4)Me-4) or XyNC (1:1:1) give [Rh(Cp)(imam)(PTo(3))](ClO(4))(2).H(2)O (8) or [Rh(Cp)(imam)(CNXy)](ClO(4))(2) (9), respectively. The crystal structures of 3 and 7.Cl have been determined.     

Chemistry in Molten Alkali Metal Polyselenophosphate Fluxes. Influence of Flux Composition on Dimensionality. Layers and Chains in APbPSe(4), A(4)Pb(PSe(4))(2) (A = Rb, Cs), and K(4)Eu(PSe(4))(2)

The reaction of Pb and Eu with a molten mixture of A(2)Se/P(2)Se(5)/Se produced the quaternary compounds APbPSe(4), A(4)Pb(PSe(4))(2) (A = Rb,Cs), and K(4)Eu(PSe(4))(2). The red crystals of APbPSe(4) are stable in air and water. The orange crystals of A(4)Pb(PSe(4))(2) and K(4)Eu(PSe(4))(2) disintegrate in water and over a long exposure to air. CsPbPSe(4) crystallizes in the orthorhombic space group Pnma (No. 62) with a = 18.607(4) ?, b = 7.096(4) ?, c = 6.612(4) ?, and Z = 4. Rb(4)Pb(PSe(4))(2) crystallizes in the orthorhombic space group Ibam (No. 72) with a = 19.134(9) ?, b = 9.369(3) ?, c = 10.488(3) ?, and Z = 4. The isomorphous K(4)Eu(PSe(4))(2) has a = 19.020(4) ?, b = 9.131(1) ?, c = 10.198(2) ?, and Z = 4. The APbPSe(4) have a layered structure with [PbPSe(4)](n)()(n)()(-) layers separated by A(+) ions. The coordination geometry around Pb is trigonal prismatic. The layers are composed of chains of edge sharing trigonal prisms running along the b-direction. [PSe(4)](3)(-) tetrahedra link these chains along the c-direction by sharing edges and corners with the trigonal prisms. A(4)M(PSe(4))(2) (M = Pb, Eu) has an one-dimensional structure in which [M(PSe(4))(2)](n)()(n)()(-) chains are separated by A(+) ions. The coordination geometry around M is a distorted dodecahedron. Two [PSe(4)](3)(-) ligands bridge two adjacent metal atoms, using three selenium atoms each, forming in this way a chain along the c-direction. The solid state optical absorption spectra of the compounds are reported. All compounds melt congruently in the 597-620 degrees C region.     

The first binuclear sandwich-like complexes based on the aromatic tetraatomic species

The first binuclear sandwich-like complexes based on the aromatic tetraatomic species with formula M(2)(η(4)-E(4))(2) (M = Al, Ga; E = N, P, As) have been studied by density functional theory (DFT). The stable conformer for each M(2)(η(4)-E(4))(2) is the staggered one with D(4d) symmetry except for Ga(2)(η(2)-N(4))(2) with C(2v) symmetry. Natural bonding orbital (NBO) analysis indicates that the metal-metal bonds of Al(2)(η(4)-E(4))(2) (E = N, P, As) and Ga(2)(η(4)-E(4))(2) (E = P, As) are all σ single bonds, which are derived mostly from the s and p(z) orbitals of the metal atoms by molecular orbital (MO) analysis. For M(2)(η(4)-E(4))(2) (M = Al, Ga; E = P, As), the metal-ligand interactions are covalent, while for Al(2)(η(4)-N(4))(2) the interactions between the Al atoms and the N(4)(2-) ligands are ionic. According to the calculated dissociation energies for breaking metal-metal bonds, the Al-Al and Ga-Ga bonds are very strong indicating that these stable sandwich-like compounds Al(2)(η(4)-E(4))(2) (E = N, P, As) and Ga(2)(η(4)-E(4))(2) (E = P, As) may be synthesized in future experiments. The nitrogen-rich compounds Al(2)(η(4)-N(4))(2) and Ga(2)(η(2)-N(4))(2) may be used as potential candidates of high energy density materials (HEDMs). Nucleus-independent chemical shifts (NICS) values reveal that the E(4)(2-) rings in the Al(2)(η(4)-E(4))(2) (E = N, P, As) and Ga(2)(η(4)-E(4))(2) (E = P, As) species possess conflicting aromaticity (σ antiaromaticity and π aromaticity) and with the same ligands, the E(4)(2-) ligands in Ga(2)(η(4)-E(4))(2) have more aromaticity than those in Al(2)(η(4)-E(4))(2).     

Further study of the reaction of Fe2+ with CN-: synthesis and characterization of cis and trans [FeII,III(CN)4L2]n- complexes

The reaction of Fe2+ with CN-, which was first performed in 1704, has been used to synthesize a new series of basic [FeII,III(CN)4L2]n- complexes, where L is a monodentate ligand. trans-Na2[FeII(CN)4(DMSO)2] and cis-[NEt4]2[FeII(CN)4(pyridine)2] are synthesized by the direct reaction of FeCl2 with 4 equiv of CN- in DMSO or pyridine. Air oxidation of the latter compound gives cis-[NEt4][FeIII(CN)4(pyridine)2]. The non-cyanide ligands in these complexes undergo facile ligand exchange reactions with solvent. Reaction of cis-[NEt4]2[FeII(CN)4(pyridine)2] with CO at room temperature gives trans-[NEt4]2[FeII(CN)4(pyridine)(CO)].