Metallophilic interactions in iodido(2,2′:6′,2′′‐terpyridine)platinum(II) diiodidoaurate(I)

In the title compound, [PtI(C₁₅H₁₁N₃)][AuI₂], the [PtI(terpy)]⁺ cations (terpy is 2,2′:6′,2′′‐terpyridine) stack in pairs about inversion centers through Pt...Pt interactions of 3.5279 (5) Å. The [AuI₂]⁻ anions also exhibit pairwise stacking, with Au...I distances of 3.7713 (5) Å. The [PtI(terpy)]⁺ cations and [AuI₂]⁻ anions aggregate forming infinite arrays of stacked ...({[PtI(terpy)]⁺...[PtI(terpy)]⁺}...{[AuI₂]⁻...[AuI₂]⁻})... units.     

Diheterocyclic compounds from dithiocarbamates and derivatives thereof. I. 2,2′-(arylenediamino)bisbenzoazoles, 2,2′-(arylenediamino)bis(imidazopyridines) and 8,8′-(arylenediamino)bispurines

A general method for the synthesis of the title compounds 5, 6, 10, 14, 15 and 16 is reported. All of them were prepared in one step from readily available dimethyl N,N'-(arylene)bisdithiocarbamates 1 and red mercury(II) oxide. The superiority of these reagents over the corresponding diisothiocyanates 7 and the synthetic utility of tetramethyl N,N'-(arylene)bisdithiocarbonimidates 2 are also discussed.     

Structures of 3,3′-dicarbometoxy-2,2′-bipyridine complexes with silver(I) and copper(II) cations

The structures of 3,3′-dicarbometoxy-2,2′-bipyridine (dcmbpy) complexes with copper(II) and silver(I) cations have been determined using single crystal X-ray-diffraction. The crystals of Cu(dcmbpy)Cl₂ are monoclinic, C2/c, a = 16.966(3), b = 18.373(3), c = 13.154(2) Å, β = 126.543(3)°. The crystals of Ag(dcmbpy)NO₃ · H₂O are also monoclinic, C2/c, a = 16.7547(13), b = 11.0922(9), c = 18.7789(18) Å, β = 100.228(7)°. The results have been compared with the literature data on the complexes of dcmbpy and its precursors: 2,2′-bipyridine (bpy) and 3,3′-dicarboxy-2,2′-bipyridine (dcbpy). Two types of complexes of 3,3′-carboxy derivatives of bpy are distinguished: (1) with metal atom bonded to two N atoms of the same molecule and (2) with metal atom bonded to two N atoms of two different molecules. The Cu(dcmbpy)Cl₂ complex belongs to the first type, whereas Ag(dcmbpy)NO₃ · H₂O belongs to the second type.     

Diheterocyclic compounds from dithiocarbamates and derivatives thereof. II. 2,2′-Diamino-6,6′-bibenzoazoles

The readily available dithiocarbamates and dithiocarbonimidates 4, 8, 14 and 15 afford in one step the title compounds in medium to very good yields. In each case, the choice of reagent depends on the nature of the group to be introduced. Their usefulness as synthetic equivalents of weakly reactive or unavailable isothiocyanates is also discussed.     

Mass spectral fragmentation pattern of 2,2′-bipyridyls. Part II. 5-Hydroxy- and 5-alkoxy-2,2′-bipyridyls

The mass spectra of 5-hydroxy-, 5-methoxy-, 5-ethoxy- and 5-propoxy-2,2′-bipyridyls are reported. The fragmentation proposals are supported by high resolution mass measurements and metastable transitions.     

Cobalt(II) and cobalt(III) complexes with 4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine

4′‐Cyanophenyl‐2,2′:6′,2′′‐terpyridine (cptpy) was employed as an N,N′,N′′‐tridentate ligand to synthesize the compounds bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(II) bis(tetrafluoridoborate) nitromethane solvate, [Co^II(C₂₂H₁₄N₄)₂](BF₄)₂·CH₃NO₂, (I), and bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(III) tris(tetrafluoridoborate) nitromethane sesquisolvate, [Co^III(C₂₂H₁₄N₄)₂](BF₄)₃·1.5CH₃NO₂, (II). In both complexes, the cobalt ions occupy a distorted octahedral geometry with two cptpy ligands in a meridional configuration. A greater distortion from octahedral geometry is observed in (I), which indicates a different steric consequence of the constrained ligand bite on the Co^II and Co^III ions. The crystal structure of (I) features an interlocked sheet motif, which differs from the one‐dimensional chain packing style present in (II). The lower dimensionality in (II) can be explained by the disturbance caused by the larger number of anions and solvent molecules involved in the crystal structure of (II). All atoms in (I) are on general positions, and the F atoms of one BF₄⁻ anion are disordered. In (II), one B atom is on an inversion center, necessitating disorder of the four attached F atoms, another B atom is on a twofold axis with ordered F atoms, and the C and N atoms of one nitromethane solvent molecule are on a twofold axis, causing disorder of the methyl H atoms. This relatively uncommon study of analogous Co^II and Co^III complexes provides a better understanding of the effects of different oxidation states on coordination geometry and crystal packing.     

Mass spectral fragmentation pattern of 2,2′-bipyridyls. Part VII 2,2′-dithiodipyridine

The mass spectral fragmentation of 2,2′ -dithiodipyridine involves loss of the elements S, SH and S₂ from the molecular ion in addition to rupture of the central bonds. Molecular rearrangements accompany the disintegration.     

Mass spectral fragmentation pattern of 2,2′-bipyridyls. Part XII. 2,2′-Selenodipyridine

The mass spectrum of 2,2′-selenodipyridine obtained by electron impact is reported. The base peak in the spectrum is due to the C₅H₄N⁺ ion formed principally by rupture of the central bonds. The molecular ion gives rise to a peak of 50% of the intensity of the base peak. Other fragmentations include loss of H, Se and CSe from the molecular ion and HCN from the M-1 ion.     

Mass spectral fragmentation pattern of 2,2′-bipyridyls Part XI. 2,2′-Iminodipyridine

The base peak in the mass spectrum of 2,2′-iminodipyridine is due to the M-1 ion. There are several minor fragmentation routes from the molecular ion but the principal pathway involves rupture of the central bonds. J. Heterocyclic Chem., 14, 1103 (1977)     

The effect of 2,2′-bipyridine, 2,2′:6′,2″-terpyridine and 1,10-phenantroline on radiation reduction of Rh(II) to Rh(I) complexes

Rh(II) acetate binuclear complexes have been reduced by gamma rays to Rh(I) complexes when 2,2′-bipyridine, 2,2′:6′,2″-terpyridine or 1,10-phenantroline ligands are present in aqueous methanol systems. These complexes exist in several forms possessing different absorption spectra. Their concentration depends on the ratio of the initial concentration of the ligands to Rh(II).     

Muss spectral fragmentation pattern of 2,2′-bipyridyis. Part VI. 2,2′- thiodipyridine

The mass spectral fragmentation of 2,2′-thiodipyridine is reported. The base peak is due to the M? I ion. The principal fragmentation routes involve loss of H, CS, CHCS and HCN from the molecular ion and CS, HCN and S from the. M-I species. Rupture of the central bonds is also an important disintegration pathway.     

Mass spectral fragmentation pattern of 2,2′-Bipyridyls. Part III. 2-(2-pyridyl)quinoline and 2,2′-Biquinoline

The mass spectral fragmentation patterns of 2-(2-pyridyl)quinoline and 2,2′-biquinoline are reported. The former rearranges to acridine derivatives on electron impact while the latter shows very little fragmentation.     

Supramolecular interactions in a copper(II) 4′‐(4‐bromophenyl)‐2,2′:6′,2′′‐terpyridine complex

The title compound, [4′‐(4‐bromophenyl)‐2,2′:6′,2′′‐terpyridine]chlorido(trifluoromethanesulfonato)copper(II), [Cu(CF₃O₃S)Cl(C₂₁H₁₄BrN₃)], is a new copper complex containing a polypyridyl‐based ligand. The Cu^II centre is five‐coordinated in a square‐pyramidal manner by one substituted 2,2′:6′,2′′‐terpyridine ligand, one chloride ligand and a coordinated trifluoromethanesulfonate anion. The Cu—N bond lengths differ by 0.1 Å for the peripheral and central pyridine rings [2.032 (2) (mean) and 1.9345 (15) Å, respectively]. The presence of the trifluoromethanesulfonate anion coordinated to the metal centre allows Br...F halogen–halogen interactions, giving rise to the formation of a dimer about an inversion centre. This work also demonstrates that the rigidity of the ligand allows the formation of other types of nonclassical interactions (C—H...Cl and C—H...O), yielding a three‐dimensional network.     

The phenomenon of conglomerate crystallization. XIX. Clavic dissymmetry in coordination compounds. XVII

[Co(NH₃)₄(oxalato)]NO₃·H₂O (1) crystallizes as a conglomerate in space groupP2₁2₁2₁ with unit cell constants ofa=7.944(3),b=9.904(11), andc=12.700(2) Å;V=999.15 ų;d(calc.;z=4)=1.968 g cm^–3. [Co(NH₃)₄(oxalato)]¦·H₂O (2) crystallizes in space groupP2₂/n with cell constants ofa=7.285(1),b=9.959(3),c=15.410(5) Å;=102.63(2)° andV=1090.98 ų; d(calc;z=4) = 2.192 g cm^–3. Data were collected over the ranges of 4°270° and 4°255°, respectively for compounds1 and2. This resulted in a total of 2515 and 2823 data for the solution and refinement of the structures of compounds1 and2, respectively. When the refinements converged, the finalR(F) andR _w (F) values were, respectively, 0.073 and 0.080 for1 and 0.0378 and 0.0353 for2.Since neither data set was sufficiently good to give a sensible set of positions for all of the hydrogens, the stereochemistry of the two cations could only be defined by the positions of the heavy atoms. In the absence of reliable amine hydrogen positions, N(amine)-O(nitrate and oxalate) distances were examined. Close N(amine)-O(nitrate and oxalate) contacts indicate the presence of a network of significant hydrogen bonds in1. The N-O distances for compound2 also show the presence of hydrogen bonding between the amines and the oxalate ligand and water; however, the bonds are not of the same magnitude as the interactions involving the nitrate oxygens in1. Despite the similarity between the cations of1 and2, the Co-N distances in the two do not exhibit the same pattern. In1, the Co-N distances for amines trans to one another are shorter than the Co-N distances for amines trans to oxalate oxygens; this effect is reversed in2.     

The phenomenon of conglomerate crystallization. XVIII. Clavic dissymmetry in coordination compounds. XVI

The x-ray crystal structure of {[Co(NH₃)₄(CO₃)]NO₃}₂ · H₂O has been determined as part of a study of the intra- and interionic interactions present in crystals of several transition-metal-amine complexes chosen to examine the occurrence and causes of conglomerate crystallization. {[Co(NH₃)₄(CO₃)]NO₃}₂ · H₂O crystallizes in the monoclinic space group P2₁/n with cell constantsa=7.4960(9)Å,b=22.673(6),c=10.513(1), and=91.41(1)°;V=1786.12 ų, andd(calc;Z=4)=1.915 g cm^–3. In all, 5333 data were collected over the range of 4° 2 60°; of these, 3395 [independent and with /3(1)] were used in the structural analysis. Data were corrected for absorption (=19.361 cm^–1) and the relative transmission coefficients ranged from 0.9987 to 0.8013. The data were of a quality such that both ammonia and water hydrogens were found in difference Fourier maps. The finalR(F) andR _w(F) residuals were, respectively, 0.0333 and 0.0332. A trans effect is observed for both cations of {[Co(NH₃ (CO₃)]NO₃}₂ · H₂O. The equatorial nitrogens, trans to the carbonato oxygens, have shorter Co-N distances than the axial nitrogens, trans to one another. The carbonato ligands are not symmetrically bonded to their respective metal centers. The Co-O distances for cation 1 are 1.913(1) and 1.903(1) Å and those for cation 2 are 1.916(1) and 1.896(1) Å. The structure reveals the existence of an intricate array of hydrogen bonds, involving both the chelating and nonchelating oxygens of the carbonato ligands as hydrogen bond acceptors of the amine hydrogens. The amine hydrogens are also involved in significant hydrogen-bonding interactions with the nitrate oxygens and water of crystallization, although they are generally weaker than those of the carbonato oxygens.     

Dispersion polymerization of acrylamide: Part II. 2,2′‐Azobisisobutyronitrile initiator

Dispersion polymerization of acrylamide in tert‐butyl alcohol (TBA)‐water media (TBA ⩾ 50 vol %) using poly(vinyl methyl ether) (PVME) as the stabilizer and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator at 50°C has been studied. The conversion‐time curve shows autoacceleration taking place from the very early stage of the reaction (measured from 4% conversion level). Molecular weight increases with conversion indicating that the gel effect is operative. This suggests that a major part (if not the whole) of the polymerization occurs in the particle phase. The effects of the concentrations of the stabilizer, the initiator, the monomer, and the solvent composition on particle size have been explained on the basis of particle phase polymerization. The feeding of the particles by the monomer presumably occurs through the solvent channels of the swollen particles. The swelling data of polyacrylamide films in various TBA‐water mixtures are given. The similarity and differences between the AIBN and ammonium persulfate (APS) initiated systems (published earlier by us) have been discussed. In general, particles are more polydisperse and bigger in the former case than in the latter. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 493–499, 1999     

Synthesis,Coordination, and Spectroscopic Properties of 2,2′‐Bipyridyldimesitylpalladium(II) and 6‐Mesityl‐2,2′‐bipyridyldimesitylpalladium(II)

The synthetic route to the dimesitylpalladium(II) complex [(bpy)PdMes₂] ( 1 ) (Mes = mesityl = 2,4,6‐trimethyl phenyl) does not only give the desired compound but also the 6‐mesityl‐2,2′bipyridyldimesitylpalladium [(6‐Mes‐bpy)PdMes₂] ( 2 ) complex and the free ligand 6,6′‐dimesityl‐2,2′‐bipyridine in reasonable yields. Single crystals of 2 were examined by X‐Ray diffraction. The compound reveals a sterically crowded molecular structure. An intramolecular π‐stacking interaction was found between the mesityl substituent on the bipyridine ligand and the adjacent mesityl ligand. The electrochemical behaviour of 1 and 2 together with a related compound was examined at various temperatures showing two reversible reduction reactions and reversible one‐electron oxidation steps at low temperatures. The latter are assigned to Pd^II/Pd^III couples.     

Mass spectral fragmentation pattern of 2,2′-bipyridyls. Part VIII. 2,2′-Bipyridyl-5-carboxylic Acid and 2,2′-bipyridyl-5-sulphonic acid

The mass spectra of 2,2′-bipyridyl-5-carboxylic acid and 2,2′-bipyridyl-5-sulphonic acid obtained by electron impact are described. The principal initial fragmentation routes from the molecular ion of the carboxylic acid involve loss of CO, CN^˙, HCN, CO₂, OH^˙ and H₂O. From the molecular ion of the sulphonic acid the principal fragmentations are accompanied by loss of HCN, O₃, SO₂ and SO₃.     

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.