Axially Dissymmetric diphosphines in the Biphenyl Series: Crystal structures of three new group-VIII metal complexes of (6,6′-dimethyl-1,1′-biphenyl-2,2′-diyl)bis(diphenylphosphine) ( = biphemp)

(6,6′-Dimethyl-1,1′-biphenyl-2,2′-diyl)bis(diphenylphosphine) ( = biphemp) reacts with allymetal halidesm to yeild complexes 1–3 which were transformed into the corresponding perchlorates 4–6 . The molecular structures of 4–6 were determined by X-ray analyses.     

Axially Dissymmetric Bis(triaryl)phosphines in the Biphenyl series: Synthesis of (6,6′-dimethylbiphenyl-2,2′-diyl)bis(diphenylphosphine) (‘BIPHEMP’) and analogues,and their use in Rh(I)-catalyzed asymmetric isomerizations of N,N-diethylnerylamine

The axially dissymmetric diphosphines (?)-(R)- and (+)-(S)-(6-6′-dimethylbiphenyl-2,2′-diyl)bis(diphenyl-phosphine) ((?)-(R)- 10 and (+)-(S)- 10 ; ‘BIPHEMP’) have been synthesized, starting from (R)- and (S)-6,6′-dimethylbiphenyl-2,2′-diamine ((R)- and(S)- 16 ), respectively, via Sandmeyer reaction, liathiation, and phosphinylation. Moreover, racemic 4,4′- dimethyl- and 4,4′-bis(dimethylamino)-substituted analogues 11 and 12 respectively, and the 6,6′-bridged analogues 1,11-bis(diphenylphosphino)-5,7-dihydrodibenz[c,e]oxepin (13) were synthesized and resolved into optically pure (R)- and(S)-enantiomers via complexation with di-μ-chlorob is {(R)-2-[1-(dimethylamino)ethyl]pheny-C? N}dipalladium(II) ((R)- 18 ). The molecular structures of the diphosphines (S)- 10 and (R)- 13 and of two derived cationic Rh(I) complexes,[Rh((S)- 10 )(nbd)]BF₄ and [Rh((R)- 13 )(nbd)]BF 4 were determined by x-ray analyses. Absolute configurations were established for (+)-(S)- 10 by X-ray analyses of both the free diphosphine and of the derived Rh(I) complex, and for (?)-(R)- 13 by X-ray analysis of the derived Rh(I) complex. Configurational assignments for the substituted BIPHEMP analogues 11 12 were achieved by means of ¹H-NMR comparisons. The BIPHEMP ligand 10 and analogues 11 , 12 and 13 are the first examples of optically active bis(triaylphosphines) containing the axially dissymmetric biphenyl moiety. All these new diphosphines proved to be excellent asymmetry-inducing ligands in Rh(I)-catalyzed isomerizations of N,N-diethylnerylamine affording citronellat enamine of 98-99% ee.     

(R)‐(6,6′‐Dihydroxybiphenyl‐2,2′‐diyl)bis(diphenylphosphine oxide) methanol solvate

The title compound, C₃₆H₂₈O₄P₂·CH₄O, was synthesized directly from the methoxy analogue. The crystal structure shows that one OH group interacts with an O atom of a phosphine oxide group in an adjacent mol­ecule, while the other OH group complexes with the methanol solvent molecule via intermolecular hydrogen bonds. An O atom of one phosphine oxide group interacts with the hydroxy H atom of methanol via a hydrogen bond. There are intra‐ and intermolecular π–π interactions between the phenyl rings. All these interactions result in the formation of supramolecular chiral parallelogram channels via self‐assembly.     

Dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylate and bis(dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylato‐κ2N,N′)copper(I) tetrafluoroborate

The single‐crystal X‐ray structures of dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylate, C₁₄H₁₂N₂O₄, and the copper(I) coordination complex bis(dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylato‐κ²N,N′)copper(I) tetrafluoroborate, [Cu(C₁₄H₁₂N₂O₄)₂]BF₄, are reported. The uncoordinated ligand crystallizes across an inversion centre and adopts the anticipated anti pyridyl arrangement with coplanar pyridyl rings. In contrast, upon coordination of copper(I), the ligand adopts an arrangement of pyridyl donors facilitating chelating metal coordination and an increased inter‐pyridyl twisting within each ligand. The distortion of each ligand contrasts with comparable copper(I) complexes of unfunctionalized 2,2′‐bipyridine.     

2,2′‐Bipyridinium bis(perchlorate)

The title compound, [H₂bipy](ClO₄)₂ or C₁₀H₁₀N₂²⁺·2ClO₄^?, was obtained at the interface between an organic (2,2′‐bi­pyridine in methanol) and an aqueous phase (perchloric acid in water). The compound crystallizes in space group P and comprises discrete diprotonated trans‐bipyridinium cations, [H₂bipy]²⁺, and ClO₄^? anions. The cations and anions are connected through N—H?O and C—H?O hydrogen bonds [distances N?O 2.817 (4) and 2.852 (4) Å, and C?O 3.225 (6)–3.412 (5)Å]. The C—C bond distance between the two rings is 1.452 (5) Å. The bipyridinium cation has a trans conformation and the N—C—C—N torsion angle is 152.0 (3)°.     

2,2′‐(Iminodimethylene)bis(1H‐benzimidazolium)(1+) chloride

The title compound, C₁₆H₁₆N₅⁺·Cl⁻ (nbbH⁺·Cl⁻), displays N—H⋯N, N—H⋯Cl and π–π inter­actions in the crystal packing. The Cl⁻ anion is chelated by the nbbH⁺ cation via two N—H⋯Cl hydrogen bonds. Inter‐ion N—H⋯N and N—H⋯Cl hydrogen bonds link ions related by 2₁ screw axes into chains along the c axis. These chains are further linked by glide‐plane operations to generate a three‐dimensional network, which is additionally stabilized by inter­chain π–π inter­actions.     

Four (2,2′‐bipyridyl)(ferrocenyl)boronium derivatives

Crystal structures are reported for four (2,2′‐bipyridyl)(ferrocenyl)boronium derivatives, namely (2,2′‐bipyridyl)(ethenyl)(ferrocenyl)boronium hexafluoridophosphate, [Fe(C₅H₅)(C₁₇H₁₅BN₂)]PF₆, (Ib), (2,2′‐bipyridyl)(tert‐butylamino)(ferrocenyl)boronium bromide, [Fe(C₅H₅)(C₁₉H₂₂BN₃)]Br, (IIa), (2,2′‐bipyridyl)(ferrocenyl)(4‐methoxyphenylamino)boronium hexafluoridophosphate acetonitrile hemisolvate, [Fe(C₅H₅)(C₂₂H₂₀BN₃O)]PF₆·0.5CH₃CN, (IIIb), and 1,1′‐bis[(2,2′‐bipyridyl)(cyanomethyl)boronium]ferrocene bis(hexafluoridophosphate), [Fe(C₁₇H₁₄BN₃)₂](PF₆)₂, (IVb). The asymmetric unit of (IIIb) contains two independent cations with very similar conformations. The B atom has a distorted tetrahedral coordination in all four structures. The cyclopentadienyl rings of (Ib), (IIa) and (IIIb) are approximately eclipsed, while a bisecting conformation is found for (IVb). The N—H groups of (IIa) and (IIIb) are shielded by the ferrocenyl and tert‐butyl or phenyl groups and are therefore not involved in hydrogen bonding. The B—N(amine) bond lengths are shortened by delocalization of π‐electrons. In the cations with an amine substituent at boron, the B—N(bipyridyl) bonds are 0.035 (3) Å longer than in the cations with a methylene C atom bonded to boron. A similar lengthening of the B—N(bipyridyl) bonds is found in a survey of related cations with an oxy group attached to the B atom.     

Form III of 2,2′,4,4′,6,6′‐hexanitro­azobenzene (HNAB‐III)

The crystal structure of form III of the title compound, HNAB [systematic name: bis(2,4,6‐trinitro­phenyl)diazene], C₁₂H₄N₈O₁₂, has finally been solved as a pseudo‐merohedral twin (monoclinic space group P2₁, rather than the ortho­rhombic space group C222₁ suggested by diffraction symmetry) using a dual space recycling method. The significant differences in the room‐temperature densities of the three crystalline forms allow examination of molecular differences due to packing arrangements. An interesting relationship with the stilbene analog, HNS, is discussed. Interatomic separations are compared with other explosives and/or nitro‐containing compounds.     

Preparation of 1,1′-binaphthyl-2,2′-diyl bridged ansa-bis( annulated cyclopentadienyl) titanium and -zirconium dichloride complexes

The coupling of enantiomerically enriched 2,2′-dilithio-1,1′-binaphthyl with various annulated cyclopentenones or 2-indanone proves to be a facile route for the preparation of a series of annulated bis(cyclopentadienes) or bis(indenes) bridged at a symmetrical cyclopentadienyl position. The six- or seven-membered annulated bis(tetrahydroindene) 6 or bis(hexahydroazulene) 7 ligands could readily be converted to titanium or zirconium dichloride complexes. Owing to the symmetry of the ligands, only a single C₂-symmetrical isomer of the metallocene dichloride could form. Although the faces of the cyclopentadienyl moieties are homotopic, the chiral bridge enforces a chiral conformation of the metallocene complexes. The bis(indenyl) 5 or five-membered annulated bis(tetrahydropentalene) 8 ligands could not be metalated. Unbridged 2-methyl and 2-phenyl substituted tetrahydropentalenes 27 and 28 were prepared and could readily be converted to titanium dichloride complexes.     

Photophysical, electrochemical and electrochromic properties of copper-bis(4,4′-dimethyl-6,6′-diphenyl-2,2′-bipyridine) complexes

The synthesis, solution and solid state structural characterization, photophysical and electrochemical properties of two redox forms of an electrochromic copper-bis(4,4′-dimethyl-6,6′-diphenyl-2,2′-bipyridine) complex, [Cu(3)₂]ⁿ (n=+1, +2), are presented. Both complexes were characterized in the solid state by X-ray diffraction methods on single-crystals showing that both forms exist in a pseudo-tetrahedral coordination, and a comparison with other structures was made. Like most copper(I) complexes, the red [Cu(3)₂]⁺ complex shows a rather weak emission (Φ_em=2.7×10⁻⁴, dichloromethane). The lifetime of the emitting MLCT state is 34±1 ns, as observed with time resolved emission, and transient absorption (in deoxygenated dichloromethane). Typical emission and transient absorption spectra are presented. The transient absorption spectra indicate that the MLCT state absorbs stronger than the ground state, which is relatively uncommon for metal bipyridine complexes, i.e. no ground state bleaching is observed. The green [(3)₂Cu]²⁺ complex does not show any observable emission or transient absorption, which is a common feature for Cu(II) complexes of this type. The electronic absorption spectra of the chemically and electrochemically produced copper(I/II) complexes are identical. The repeated electrochemical conversion of the Cu(I) center into Cu(II) and vice versa does not cause any decomposition. This is consistent with a fully reversible Cu(I)/Cu(II) redox couple in the corresponding cyclic voltammogram, (E_1/2 (Cu(I)/Cu(II))=+0.68 V vs. SCE=+0.23 V vs. Fc/Fc⁺). These observations indicate that no large structural reorganization occurs upon electrochemical timescales (sub second), and that the different ways of generating the complexes does not effect their final structure, apart from the small differences observed in the X-ray structures of both forms. These characteristics make these complexes rather well suited for their incorporation into an electrochromic display configuration.     

Die Reduktion von Azulen mit Natrium zum Kontaktionen-Tripel [Dinatrium-(1,1′,6,6′-Tetrahydro-6,6′-bi(azulen)-1,1′-diid)–bis (diglyme)]∞

The Sodium Reduction of Azulene to the Contact-Ion Triple [Disodium-(1,1′,6,6′-Tetrahydro-6,6′-bi(azulene)-1,1′-diide)–bis(diglyme)]_∞ Colorless air-sensitive single crystals can be grown from a diglyme solution after the reduction of azulene by a Na-metal mirror. Structure determination at 150 K reveals a dimer dianion, in which the seven-membered rings are connected in 6,6′-positions and doubly diglyme-solvated Na⁺ counter cations η⁵-coordinate to the five-membered rings. Based on preceding cyclovoltammetric measurements in aprotic azulene solutions as well as on extensive MNDO enthalpy of formation calculations, a proposal is forwarded how possibly the contact ion triple is formed along a microscopic pathway.     

2,2′‐(1,2‐Ethanediyldithio)bis(1,3‐benzothiazole)

In the title compound, C₁₆H₁₂N₂S₄, which is the result of the S‐alkyl­ation reaction of 2‐mercapto­benzo­thia­zole with ethyl­ene dibromide, the planes of the two benzo­thia­zole moieties form a dihedral angle of 3.84 (14)°. The bridging chain moiety, –SCH₂CH₂S–, adopts an antiperiplanar conformation. There are intermolecular S⃛S non‐bonded contacts of 3.6471 (9) Å, which stabilize the crystal packing.     

Crystallographic report: (2,2′‐Bipyridyl)bis(ethanoldithiocarbamato)zinc(II)

Zn(meadtc)₂(2,2′‐bipy) is a ZnS₃N₂ chromophore with a distorted square pyramidal geometry. The IR band at 1002 cm^?1 and the bond valence sum value of 1.98 confirmed the monodentate dithiocarbamate in coordination. The non‐bonding Zn–S distance is 5.004(3) Å. Copyright © 2004 John Wiley & Sons, Ltd.     

Bis(2,2′‐bipyridine)(dicyanamido)­copper(II) tetrafluoroborate

In the title compound, [Cu(C₂N₃)(C₁₀H₈N₂)₂]BF₄, the Cu^II atom shows distorted trigonal‐bipyramidal geometry, with the dicyan­amido ligand in the equatorial plane. The two out‐of‐plane Cu—N bond lengths to bi­pyridine are 2.006 (3) and 1.998 (3) Å, whereas the in‐plane Cu—N distances are 2.142 (3) and 2.043 (3) Å to the bi­pyridine, and 2.015 (3) Å to the dicyan­amide.     

(1H‐Pyrazole‐κN2)(2,2′:6′,2′′‐terpyridine‐κ3N,N′,N′′)platinum(II) bis(perchlorate) nitromethane monosolvate

The reaction between [PtCl(terpy)]·2H₂O (terpy is 2,2′:6′,2′′‐terpyridine) and pyrazole in the presence of two equivalents of AgClO₄ in nitromethane yields the title compound, [Pt(C₃H₄N₂)(C₁₅H₁₁N₃)](ClO₄)₂·CH₃NO₂, as a yellow crystalline solid. Single‐crystal X‐ray diffraction shows that the dicationic platinum(II) chelate is square planar with the terpyridine ligand occupying three sites and the pyrazole ligand occupying the fourth. The torsion angle subtended by the pyrazole ring relative to the terpyridine chelate is 62.4 (6)°. Density functional theory calculations at the LANL2DZ/PBE1PBE level of theory show that in vacuo the lowest‐energy conformation has the pyrazole ligand in an orientation perpendicular to the terpyridine ligand (i.e. 90°). Seemingly, the stability gained by the formation of hydrogen bonds between the pyrazole NH group and the perchlorate anion in the solid‐state structure is sufficient for the chelate to adopt a higher‐energy conformation.     

Synthesis of C-5 benzoyl and azido functionalized 2,2′-dithiobis-and 2,2′-diselenobis(1H-indoles)

Novel methods for the synthesis of C-5 benzoyl and azido analogues of 2,2′-dithiobis(1H-indole), 1, and 2,2′-diselenobis(1H-indole), 2, are described to further explore the structure activity relationships in this region of the molecule. Analogues 3-i displayed inhibitory activity (IC₅₀ = 0.45-2.03 μ) toward the catalytic domain of the epidermal growth factor receptor tyrosine kinase that was equivalent to or better than that of unsubstituted compounds 1 and 2. The regiochemistry of Friedel-Crafts benzoylation onto 1 was determined by X-ray crystallography. To test the potential for compounds of this class to interact with the epidermal growth factor receptor tyrosine kinase via a sulfhydryl exchange mechanism, reaction of a 2,2′-dithiobis(1H-indole) with glutathione was carried out and the product characterized.     

A chloro(2‐pyridinecarboxaldehyde)(2,2′:6′,2′′‐ter­pyridine)­ruthenium(II) complex

The aldehyde moiety in the title complex, chloro(2‐pyridinecarboxaldehyde‐N,O)(2,2′:6′,2′′‐terpyridine‐κ³N)ruthenium(II)–chloro­(2‐pyridine­carboxyl­ic acid‐N,O)(2,2′:6′,2′′‐ter­pyridine‐κ³N)­ruthenium(II)–perchlorate–chloro­form–water (1.8/0.2/2/1/1), [RuCl­(C₆H₅NO)­(C₁₅H₁₁N₃)]_1.8[RuCl­(C₆H₅­NO₂)(C₁₅H₁₁N₃)]_0.2­(ClO₄)₂·­CHCl₃·­H₂O, is a structural model of substrate coordination to a transfer hydrogenation catalyst. The title complex features two independent Ru^II complex cations that display very similar distorted octahedral coordination provided by the three N atoms of the 2,2′:6′,2′′‐ter­pyridine ligand, the N and O atoms of the 2‐pyridine­carbox­aldehyde (pyCHO) ligand and a chloride ligand. One of the cation sites is disordered such that the aldehyde group is replaced by a 20 (1)% contribution from a carboxyl­ic acid group (aldehyde H replaced by carboxyl O—H). Notable dimensions in the non‐disordered complex cation are Ru—N 2.034 (2) Å and Ru—O 2.079 (2) Å to the pyCHO ligand and O—C 1.239 (4) Å for the pyCHO carbonyl group.     

Diheterocyclic compounds from dithiocarbamates and derivatives thereof. V. 4,4′-dioxo-2,2′-dithioxo(dioxo)-6,6′-biquinazolines

The title compounds 3, 5 and 9 were synthesized in a one step procedure from dithiocarbamates 2 or dithiocarbonimidates 7 in medium to high yields. The usefulness of 2 and 7 as synthetic equivalents of unstable or unavailable isocyanates and isothiocyanates is also discussed.     

Synthesis of polyamide-pyrazolones from 2,2′-disubstituted bis(4-ethoxymethylene-5-oxazolone) and aromatic dihydrazines

A new class of polyamide-pyrazolones was synthesized by the vinylogous nucleophilic substitution polymerization, which was followed by rearrangement, from 2,2′-p-phenylenebis(4-ethoxymethylene-5-oxazolone) and aromatic dihydrazines. Solution polymerization was carried out in polar aprotic solvents under mild conditions to yield polymers having inherent viscosities in the range of 0.5–1.2 quantitatively. The polymer derived from bis(4-hydrazinophenyl) sulfone was readily soluble in strongly polar solvents, while that from bis(4-hydrazinophenyl)methane was partially soluble or swelled in these solvents. The polyamide-pyrazolones which are presumed to contain some intermediate oxazolone structure showed a low level of thermal stability.