Novel results obtained by freezing berry pseudorotation of phosphoranes (10‐P‐5)

By freezing Berry pseudorotation of spirophosphoranes with recourse to the rigidity of the Martin bidentate ligand, we successfully prepared configurationally stable enantiomeric pairs of optically active phosphoranes, and could isolate “anti‐apicophilic” C‐apical O‐equatorial (O‐cis) phosphoranes. The effect of σ*_{P O} orbital of the O‐cis phosphorane was investigated both experimentally and theoretically. O‐cis phosphoranes were revealed to be much more electrophilic at the phosphorus atom than O‐trans isomers by experimental studies. The acidity of the α‐proton of an O‐cis benzylphosphorane was found to be higher than that of the corresponding O‐trans isomer. By the reaction of the α‐carbanion of an O‐cis benzylphosphorane with PhCHO, we succeeded in the first isolation and full structural characterization of a 12‐P‐6 phosphate bearing an oxaphosphetane ring, the intermediate in the Wittig type reaction using a 10‐P‐5 phosphorane. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:390–396, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10072     

4‐Ethoxycarbonyl‐3‐hydroxy‐3‐phenylcyclohexanone

The title compound, ethyl 2‐hydroxy‐4‐oxo‐2‐phenyl­cyclo­hexane­carboxyl­ate, C₁₅H₁₈O₄, was obtained by a Michael–Aldol condensation and has the cyclo­hexanone in a chair conformation. The attached hydroxy, ethoxy­carbonyl and phenyl groups are disposed in β‐axial, β‐equatorial and α‐­equatorial configurations, respectively. An intermolecular hydrogen bond, with an O?O distance of 2.874 (2) Å, links the OH group and the ring carbonyl. Weak intermolecular C—H?O=C (ester and ketone), O—H?O=C (ketone) and C—H?OH hydrogen bonds exist.     

Mixed‐ligand Complexes with 2,6‐Pyridinedicarboxylato(2‐) and 4,7‐Diphenyl‐1,10‐Phenanthroline Ligands, [MII(pdc)(DPphen)(H2O)]·H2O (M = Co or Cu). Synthesis,Crystal Structures and Properties

Iso‐type [M^II(pdc)(DPphen)(H₂O]·H₂O compounds (M = Co or Cu, pdc = 2,6‐pyridinedicarboxylato(2‐) ligand and DPphen = 4,7‐diphenyl‐1,10‐Phenanthroline) were synthesized and studied by X‐ray diffraction, thermal and spectral methods. The N,N′‐equatorial bidentate DPphen‐copper(II) chelation imposes a mer‐N(equatorial)+O₂(apical) conformation to pdc in the coordination polyhedron (type 4+1+1). In the Co(II) derivative, the coordination is of type 1+2+2+1 because of a lesser Jahn‐Teller distortion. In the crystals, π,π‐interligand interactions between phen ligands connect the complex molecules in multi‐stacked chains. Aqua···O(carboxyl) H‐bonding interactions reinforce the stacked chains and build double chains in 1D supramolecular structures parallel to the a axis. Non coordinated water connect these structures by H‐bonds.     

Transition metal complexes with thiosemicarbazide‐based ligands. XLIV. Aqua(3‐hydroxy‐5‐hydroxymethyl‐2‐methylpyridine‐4‐carboxaldehyde 3‐­methylisothiosemicarbazone‐κ3O,N1,N4)nitratocopper(II) nitrate

The title complex, [Cu(NO₃)(C₁₀H₁₄N₄O₂S)(H₂O)](NO₃), is the first metal complex with a Schiff base derived from iso­thio­semicarbazide and pyridoxal (pyridoxal is 3‐hydroxy‐5‐­hydroxy­methyl‐2‐methyl­pyridine‐4‐carbox­aldehyde). The Cu^II environment is a square pyramid, the equatorial plane of which is formed by the tridentate ONN‐coordinated iso­thio­semicarbazone and one water mol­ecule, while the nitrate ligand is in the apical position. The existence of numerous strong intermolecular hydrogen bonds, and weak C—H?O and C—H?π interactions, leads to a three‐dimensional supramolecular structure.     

3‐P⩵O‐Functionalized Phospholane 1‐Oxides by the Michael Reaction of 1‐Phenyl‐2‐phospholene 1‐Oxide and Dialkyl Phosphites,H‐Phosphinates,or Diphenylphosphine Oxide

The addition of dialkyl phosphites, H‐phosphinates, and diphenylphosphine oxide on the β carbon atom of the not too reactive double bond of 1‐phenyl‐2‐phospholene 1‐oxide was carried out in two ways. According to the first approach (A), the P‐reagents were activated by trimethylaluminum prior to the Michael addition. The second method (B) involved the microwave(MW)‐assisted solventless reaction of the P‐species with the phospholene oxide. In general, method A was more efficient and more selective than route B. However, the addition of dialkyl phosphites and diphenylphosphine oxide could also be accomplished well under MW conditions. The disadvantage of the MW‐assisted approach is that the Michael adducts are formed as a mixture of isomers. The 3‐P⩵O‐phospholane oxides are novel products, and among these, the bis(phosphine oxide) is the precursor of the bidentate P‐ligand LuPhos.     

Easily Accessible Auxiliary for Palladium‐Catalyzed Intramolecular Amination of C(sp2)H and C(sp3)H Bonds at δ‐ and ε‐Positions

An easily synthesized and accessible N,O‐bidentate auxiliary has been developed for selective C? H activation under palladium catalysis. The novel auxiliary showed its first powerful application in C? H functionalization of remote positions. Both C(sp²)? H and C(sp³)? H bonds at δ‐ and ε‐positions were effectively activated, thus giving tetrahydroquinolines, benzomorpholines, pyrrolidines, and indolines in moderate to excellent yields by palladium‐catalyzed intramolecular C? H amination.     

Isolation of a Reactive Tricoordinate α‐Oxo Gold Carbene Complex

The [(P,P)Au=C(Ph)CO₂Et]⁺ complex 3 [where (P,P) is an o‐carboranyl diphosphine ligand] was prepared by diazo decomposition at ?40 °C. It is the first α‐oxo gold carbene complex to be characterized. Its crystallographic structure was determined and DFT calculations have been performed, unraveling the key influence of the chelating (P,P) ligand. The gold center is tricoordinate and the electrophilicity of the carbene center is decreased. Complex 3 mimics transient α‐oxo gold carbenes in a series of catalytic transformations, and provides support for the critical role of electrophilicity in the chemoselectivity of phenol functionalization (O?H vs. C?H insertion).     

7‐Phenyl‐1‐oxa‐4‐thiaspiro[4.5]decan‐7‐ol stereoisomers

The stereoisomers of 7‐phenyl‐1‐oxa‐4‐thia­spiro­[4.5]­decan‐7‐ol, C₁₄H₁₈O₂S, have the same stereochemistry at the C atom bearing an OH group, i.e. axial OH and equatorial phenyl groups. However, the acetal S and O atoms are axial and equatorial, respectively, in one isomer and reversed in the second. Furthermore, the crystals of one isomer are composed of hydrogen‐bonded mol­ecules involving the hydroxyl H atom and the O atom of the five‐membered heterocyclic ring, with an O?O distance of 2.962 (3) Å, forming a polymeric chain along the b axis. The asymmetric unit of the other isomer is composed of two mol­ecules, wherein hydroxyl H atoms and the O atoms of the five‐membered heterocyclic rings display intramolecular O—H?O hydrogen bonds with O?O separations of 2.820 (2) and 2.834 (2) Å.     

Bis(3‐amino­pyridine‐κN)(4,4′‐di­methyl‐2,2′‐bipyridine‐κ2N,N′)(per­chlorato‐κO)copper(II) per­chlorate

The title compound, [Cu(ClO₄)(C₅H₆N₂)₂(C₁₂H₁₂N₂)]ClO₄, was prepared by in situ partial ligand substitution between 3‐amino­pyridine and 4,4′‐dimethyl‐2,2′‐bipyridine at room temperature. The central copper(II) ion is five‐coordinated by one bidentate 4,4′‐dimethyl‐2,2′‐bipyridine mol­ecule, two monodentate pyridine‐coordinated 3‐amino­pyridine mol­ecules and one apical O atom from the perchlorate counter‐ion. Inter­molecular N—H⋯O and C—H⋯O hydrogen‐bonding inter­actions form a hydrogen‐bond‐sustained network.     

Aqua(dipicolinato‐κ3O,N,O′)(1H‐imidazole‐κN3)(1,10‐phenanthroline‐N,N′)manganese(II)

In the title compound, [Mn(C₇H₃NO₄)(C₃H₄N₂)(C₁₂H₈N₂)(H₂O)], the Mn^II centre is surrounded by one bidentate phenanthroline ligand [Mn—N = 2.383 (3) and 2.421 (3) Å], one tridentate dipicolinate ligand [Mn—N = 2.300 (3) Å, and Mn—O = 2.300 (2) and 2.357 (2) Å], one monodentate imidazole ligand [Mn—N = 2.238 (3) Å] and one water molecule [Mn—O = 2.157 (3) Å]. It displays a distorted pentagonal‐bipyramidal geometry, with neighbouring angles within the equatorial plane ranging from 68.05 (9) to 77.48 (10)°. Intermolecular O—H...O hydrogen bonds link the molecules into infinite chains. The chains are crosslinked by hydrogen bonds involving the carboxyl O atoms of the dipicolinate ligand and the protonated imidazole N atom, leading to an infinite two‐dimensional network sheet packing mode. The complete solid‐state structure can be described as a three‐dimensional supramolecular framework, stabilized by these intermolecular hydrogen‐bonding interactions and π–π stacking interactions involving the phenanthroline rings.     

Synthesis,spectroscopic exploration,biocidal activities,and crystal structures of 3‐(3‐fluorophenyl)‐2‐phenylpropenoic acid and trimethyltin(IV) complex

The ligand, 3‐(3‐fluorophenyl)‐2‐phenylpropenoic acid, [C₁₅H₁₁FO₂] ( I ) was prepared by reacting equimolar amount of phenyl acetic acid with 3‐fluorobenzaldehyde (1:1) using Perkin condensation method. The trimethyltin(IV) carboxylate, [Me₃SnO₂FH₁₀C₁₅] ( II ) was synthesized by refluxing an equimolar (1:1) mixture of trimethyltin chloride and silver salt of the ligand acid, [C₁₅H₁₀FO₂Ag] ( Ia ). The ligand and complex both were characterized by elemental analysis, IR, mass, ¹H NMR, and X‐ray crystallographic data. On the basis of ¹H NMR data, (²J[^117/119Sn, ¹H] and C Sn C bond angle), it is concluded that the environment around the tin atom in solution is tetrahedral. The Infrared spectroscopic results showed that trimethyltin(IV) derivative has 5‐coordinated polymeric structure with bridging carboxylate groups in the solid state, which has been confirmed by the X‐ray crystallographic data. The crystal of ligand acid ( I ) is triclinic with space group Pbar1. However, the crystal of the complex ( II ) is monoclinic with space group C_2/c. The geometry around the tin atom is distorted trigonal bipyramid with O(1) and O(2) atoms in apical positions. The ligand ( I ) and complex ( II ) were also tested for their biocidal activities. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:398–406, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20032     

Di‐μ‐formato‐1κ2O:2κ2O′‐di‐μ‐pyridin‐2‐olato‐1κO:2κN;1κN:2κO‐bis­[(2‐pyridone‐κO)copper(II)] acetonitrile 1.02‐solvate

In the title compound, [Cu₂(CHO₂)₂(C₅H₄NO)₂(C₅H₅NO)₂]·1.02CH₃CN, the dimeric unit is centrosymmetric, with two bidentate pyridin‐2‐olate and two bidentate formate syn–syn bridges, and two apical 2‐pyridone ligands coordinated through the O atoms. The N atom from the apical 2‐pyridone ligand is a donor of a hydrogen bond to the O atom of the bridging pyridinolate ligand of the same complex. The coordination polyhedron of the Cu atom is a distorted square pyramid.     

catena‐Poly[[diaquabis(2‐chloronicotinato‐κ2O,O′)cadmium(II)]‐μ‐2‐chloronicotinato‐κ3O,O′:N]

In the title neutral coordination polymer, [Cd(C₆H₃ClNO₂)₂(H₂O)₂]_n, each Cd^II ion is coordinated by one N and four O atoms from three 2‐chloro­nicotinate ligands and by two aqua ligands, defining a distorted monocapped octahedral coordination geometry. Adjacent Cd atoms are linked by the pyridyl N atom and the bidentate carboxyl­ate functional group of a 2‐­chloro­nicotinate ligand, forming a one‐dimensional infinite chain along the b axis. The Cd⋯Cd distance is 8.112 (3) Å. These chains are linked by O—H⋯O and O—H⋯N hydrogen bonds into a three‐dimensional network structure.     

Synthesis and Crystal Structure of [Pb(trz)(tfpb)(H2O)]: a Lead(II) Complex Containing 2,4,6‐Tris(2‐pyridyl)‐1,3,5‐triazine and 4,4,4‐Trifluoro‐1‐phenyl‐1,3‐butandionate

[Pb(trz)(tfpb)(H₂O)] ( 1 ) (trz and tfpb are the abbreviations of 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine and 4,4,4‐trifluoro‐1‐phenyl‐1,3‐butandionate, respectively) have been synthesized and characterized by elemental analysis and IR, ¹H NMR, spectroscopy. The single‐crystal structure of 1 shows the coordination number of the Pb²⁺ ions is eight with three N‐donor atoms from a “trz” ligand and four O‐donors from the dionate ligand and one molecule of water. The supramolecular features in this complex are guided by lone pair activity and control of strong hydrogen bonds, weak directional intermolecular interactions and aromatic π‐π stacking interactions.     

Aqua[bis(pyrimidin‐2‐yl‐κN)amine](carbonato‐κ2O,O′)copper(II) dihydrate

The title mononuclear complex, [Cu(CO₃)(C₈H₇N₅)(H₂O)]·2H₂O, was obtained by fixation of CO₂ by a mixture of copper(II) tetra­fluoro­borate and the ligand bis­(pyrimidin‐2‐yl)­amine in ethanol/water. The Cu^II ion of the complex has a distorted square‐pyramidal environment, with a basal plane formed by two N atoms of the ligand and two chelating O atoms of the carbonate group, while the apical position is occupied by the O atom of the coordinating water mol­ecule. In the solid state, hydrogen‐bonding interactions are dominant, the most unusual being the Watson–Crick‐type coplanar ligand pairing through two N—H?N bonds. Lattice water mol­ecules also participate in hydrogen bonding.     

Synthesis,characterization and antibacterial activity of 3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoic acid and di‐isopropylammonium [3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoato] triphenylstannate(IV). The crystal structure of [HQ][SnPh3(o‐mpspa)]

Reaction of 3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoic acid [H₂(o‐mpspa)] with SnPh₃OH in the presence of di‐isopropylamine resulted in the formation of the complex [HQ][SnPh₃(o‐mpspa)] (where HQ = di‐isopropylammonium cation and o‐mpspa = 3‐(2‐methoxyphenyl)‐2‐sulfanylpropenoato), which was characterized by mass spectrometry and vibrational spectroscopy, as well as by ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. The single‐crystal X‐ray structural analysis of the new complex shows a trigonal‐bipyramidal coordination geometry around the Sn atom where o‐mpspa behaves as a bidentate chelating ligand. Dimeric units arise from the existence of N? H…O hydrogen bonds between the NH₂ group of the di‐isopropylammonium cation and the oxygen atoms of the two neighbouring carboxylato groups. The bacteriostatic activity of the complex is also reported. Copyright © 2007 John Wiley & Sons, Ltd.     

trans‐Bis(dimethyl sulfoxide‐κO)bis(3‐oxo‐3,4‐dihydroquinoxaline‐2‐carboxylato‐κ2N1,O2)copper(II)

The title compound, [Cu(C₉H₅N₂O₃)₂(C₂H₆OS)₂], consists of octahedrally coordinated Cu^II ions, with the 3‐oxo‐3,4‐dihydroquinoxaline‐2‐carboxylate ligands acting in a bidentate manner [Cu—O = 1.9116 (14) Å and Cu—N = 2.1191 (16) Å] and a dimethyl sulfoxide (DMSO) molecule coordinated axially via the O atom [Cu—O = 2.336 (5) and 2.418 (7) Å for the major and minor disorder components, respectively]. The whole DMSO molecule exhibits positional disorder [0.62 (1):0.38 (1)]. The octahedron around the Cu^II atom, which lies on an inversion centre, is elongated in the axial direction, exhibiting a Jahn–Teller effect. The ligand exhibits tautomerization by H‐atom transfer from the hydroxyl group at position 3 to the N atom at position 4 of the quinoxaline ring of the ligand. The complex molecules are linked through an intermolecular N—H...O hydrogen bond [N...O = 2.838 (2) Å] formed between the quinoxaline NH group and a carboxylate O atom, and by a weak intermolecular C—H...O hydrogen bond [3.392 (11) Å] formed between a carboxylate O atom and a methyl C atom of the DMSO ligand. There is a weak intramolecular C—H...O hydrogen bond [3.065 (3) Å] formed between a benzene CH group and a carboxylate O atom.     

Intermolecular C—H...π interactions in 1,5‐diphenyl‐3‐(2‐pyridyl)‐2‐pyrazoline

The title compound, C₂₀H₁₇N₃, is a derivative of 1,3,5‐triaryl‐2‐pyrazoline and can act as an N,N′‐bidentate ligand. This molecule features strong fluorescence that can be explained by an extended pyridyl–C=N—N–phenyl system. The three‐dimensional structure is formed by means of an extended network of weak C—H...π hydrogen bonds supported by π–π interactions.     

A theoretical study on the conformation of 3‐phosphinoxido‐ and 3‐phosphono‐1,2,3,4,5,6‐hexahydrophosphinine 1‐oxides

The title compounds ( 2 and 4 ) obtained by the diastereoselective hydrogenation of the corresponding 1,2,3,6‐tetrahydrophosphinine oxides ( 1 and 3 ) were subjected to a detailed quantum chemical study. The possible chair conformers were calculated at the HF/6‐31G* level of theory, according to which, the 1‐phenyl‐3‐P(O)Y₂‐substituted products ( 2 ) exist in the trans₁ form, in which all substituents are equatorial. At the same time, the 1‐ethoxy‐3‐dialkylphosphono compounds ( 4 ) adopt the cis conformations, in which the 1‐ethoxy group is axial and the 3‐P(O)(OR)₂ moiety is equatorial. The major diastereomer ( 4–1 ) is cis₃, in which the 5‐methyl group is axial, while the minor one is cis₁ with an equatorial methyl substituent. It is noteworthy that the rotational position of the exocyclic P(O)Z₂ function affected the energy content of the chair conformer to a high extent. The possibility of the involvement of the twist conformers was also considered. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:520–524, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20148     

Isotopic effect on tautomeric behavior of 5‐(2,6‐disubstituted‐aryloxy)‐tetrazoles

Isotopic effect on tautomeric behaviors of the synthesized 5‐phenoxy‐ (1a), 5‐(2,6‐dimethylphenoxy)‐ (1b), 5‐(2,6‐diisopropylphenoxy)‐ (1c), 5‐(2,6‐dimethoxyphenoxy)‐ (1d) and 5‐(4‐methylphenoxy)‐tetrazole (1e) were investigated in DMSO‐d₆ by adding one drop of D₂O. Among 1a–e, 1a, 1d and 1e show small rotational barrier around C5? O1 and O1? C6 while in 1b and 1c there are distinguishable rotational barrier about that bonds. The ¹H NMR spectra of 1b and 1c show slightly different chemical shifts for two methyl and isopropyl groups on those phenyl ring, respectively, while the chemical shifts difference (Δδ) between two methyl and two isopropyl groups were enhanced by adding D₂O. The ¹³C NMR spectra of 1b show two overlapped singlets for methyl groups after adding D₂O. Representatively, the calculations of compound 1c were performed with GAUSSIAN‐03and the rotational barrier about C5? O1 and between isopropyl group and phenyl ring in 1c was calculated with B3LYP/6‐31G(d) basis set. Copyright © 2011 John Wiley & Sons, Ltd.