Tetrachlorozincate Salts Research Articles

Synthesis, reactivity, X-ray characterization and docking studies of N7/N9-(2-pyrimidyl)-adenine derivatives

The reaction of adenine with 2-chloropyrimidine yields as a major product the unexpected N7-(2-pyrimidyl)-adenine (1) and as a minor one N9-(2-pyrimidyl)-adenine (2). Both compounds have been characterized by X-ray diffraction analysis. Moreover, we report the formation of a 1:1 co-crystal (3) composed by compound (1) and adenine that was formed serendipitously during the synthesis of (1). Unexpectedly, the treatment of (1) with Brönsted acids like HCl or HNO3 causes the opening of the imidazole ring of the N7-substituted adenine, yielding N5-(pyrimidin-2-yl)pyrimidine-4,5,6-triamine (4–7) which we have X-ray characterized in its neutral, (4), monoprotonated [nitrate salt (6)] and diprotonated forms [hydrochloride salt (5) and, also, a tetrachlorozincate salt (7)]. Finally, we have used compound (5) as ligand to synthesize and X-ray characterize its complexes with Ir(III) and Ag(I) (compounds (8) and (9), respectively), where the latter is a 2D coordination polymer and the former is a discrete mononuclear complex. We have studied the supramolecular assemblies formed in the solid state by using density functional theory (DFT) calculations. Finally, DNA-docking studies of several compounds have been carried out in order to analyze their ability to interact with the DNA.

Preparation and structures of nickel(II) compounds of 2,9-meso-7,14-rac-2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane

Preparations and structures are reported for compounds of 2RS,7RS,9SR,14RS-[(2,5,5,7,9,12,14,14-octamethyl-1,4,8,11-tetrazacyclotetradecane)nickel(II)]2+: trans-octahedral [Ni(mr-III-L)(NCS)2], cis-octahedral [Ni(mr-V-L)(OAc)]ClO4 (and –H2O) with asymmetrical chelate acetato, [Ni(mr-V-L)(acac)]ClO4 and [Ni(mm1-III L)]·2[Ni(mr-V-L)(acac)](ClO4)4 with chelate pentane-2,4-dionato, trigonal pyramidal [Ni(mr-V-L)Cl]ClO4 and [Ni(mr-V-L)(NCS)]ClO4 and square-planar [Ni(mr-V-L)](ClO4)2, where III and V indicate the nitrogen configurations 1R,4S,8S,11R and 1R,4S,8R,11S respectively and mm1-L is the 2R,7S,9S,14R isomer of the amine. The preparations of [Ni(mr-V-L)(A)](ClO4), where A−=chelate nitrato, nitrito and μ-oxalato are reported.

Preparations and structures of nickel(II) compounds of 2,9-rac-2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane

The imine functions of 3,10-rac-[(3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradec-4,11-diene)nickel(II)]2+ are reduced by NaBH4 in water forming the 2RS,7SR, 9RS,14SR-, [Ni(rac-rac-1-L)]2+, and 2RS,7SR,9RS,14RS-[Ni(rac-meso-L)]2+, isomeric [(2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II)] cyclic tetraamine cations. The structures of [Ni(rac-rac-1-L)](ClO4)2, [Ni(rac-rac-1-L)]ZnCl4, [Ni(rac-rac-1-L)(acac)]ClO4 and [Ni(rac-meso-L)](ClO4)2·H2O were determined by X-ray diffractometry. The perchlorate and tetrachlorozincate salts of the cation [Ni(rac-rac-1-I-L)]2+ have near twofold symmetry about the nickel(II) ion, normal to the NiN4 plane, with “basket” cyclam nitrogen configuration I (1RS,4RS,8RS,11RS). The C2 and C9 methyl substituents are axially oriented to the same side of the plane as the four NH groups, with the axially oriented components of the C5 and C12 gem-dimethyl groups oriented to the other side. The salt [Ni(rac-rac-1-L)](NCS)2 has uncoordinated thiocyanate ions. The compound [Ni(rac-rac-1-V-L)(acac)]ClO4, with pentane-2,4-dionate chelate, has the macrocycle in configuration 1RS,2SR,4RS,7RS,8RS,9SR,11RS,14RS, folded along N4–Ni–N11, with methyl substituents on C2 and C9 equatorially oriented. The [Ni(rac-meso-L)]2+ cation was isolated as the trans-dithiocyanato compound, [Ni(rac-meso-III-L)(NCS)2], which was converted into the square-planar perchlorate salt [Ni(rac-meso-III-L)](ClO4)2H2O, with configuration 1RS,2SR,4SR,7SR,8SR,9SR,11RS,14RS. This cation has the C2 methyl substituent axially and the C9 substituent equatorially oriented.

Nickel(II) compounds of a tri-amine mono-imine macrocycle: Preparations and structures of (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradec-4-ene)nickel(II) compounds

Abstract Reduction of one imine function of (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)nickel(II) with 1 molar proportion of NaBH4 produces as the major product the tri-amine–mono-imine macrocyclic cation (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradec-4-ene)nickel(II), Ni(tm)]2+. Pairs of isomeric singlet ground state perchlorate and tetrachlorozincate salts of [Ni(tm)]2+ were prepared and the structures determined for the 1RS,8SR,11SR,12RS (labeled as β) and 1RS,8RS,11RS,12SR (labeled as α) tetrachlorozincate salts. Triplet ground state trans-β-[Ni(tm)(NCS)2] and catena-trans-{β-Ni(tm)-NC-Ni(CN)2-CN-}n·2nH2O have the macrocycle in planar coordination and α-[{Ni(tm)}2(C2O4)](ClO4)2 has the macrocycle folded. With pentane-2,4-dione the compounds [β-Ni(tm)]·[α-Ni(tm)(acac)](ClO4)3 and [Ni(teta)]·[α-Ni(tm)(acac)](ClO4)3 (teta = C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) with both square-planar and octahedral Ni(II) cations were prepared and the latter was structurally characterized. Isomerisation in solution of metastable α-[Ni(tm)]2+ to stable β-[Ni(tm)]2+ is extremely slow, even in base.

Synthesis and structures of (13-hydroxylamino-5,7,7,13-tetramethyl-1,4,8,11-tetraazacyclotetradec-4-ene-κ 4)nickel(II) tetrachlorozincate(II) and (13-azonium-5,5,7,13-tetramethyl-1,4,8,11-tetraazacyclotetradecane-κ 4)nickel(II) tetrachlorozincate(II) chloride 2.25 water

Zinc/acid reduction of the nitro function of (5,7,7,13-tetramethyl-13-nitro-1,4,8,11-tetraazacyclotetradec-4-ene)nickel(II) yields (13-hydroxylamino-5,7,7,13-tetramethyl-1,4,8,11-tetraazacyclotetradec-4-ene)nickel(II), isolated as the tetrachlorozincate salt, for which the structure is reported. This has singlet ground state nickel(II) in square-planar coordination by the three amine and the imine nitrogen atoms of the macrocycle. There is no interaction between the nickel(II) ion and the axially oriented hydroxylamino group. Zinc/acid reduction of the nitro function of (5,5,7,13-tetramethyl-13-nitro-1,4,8,11-tetraazacyclotetradecane)nickel(II) yields (13-amino-5,5,7,13-tetramethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II), isolated from acid solution as (13-azonium-5,5,7,13-tetramethyl-1,4,8,11-tetraazacyclotetradecane-κ 4)nickel(II) tetrachlorozincate(II) chloride 2.25 water, for which the structure is reported. The two independent cations have singlet ground state nickel(II) in square-planar coordination by the four secondary amine nitrogen atoms of the macrocycle, with the protonated amine substituent axially oriented. The cations of both compounds show disorder in the location of the axial methyl component of the gem-dimethyl group, manifest as reversal of the trimethyl substituted 1,3-amine-imine or 1,3-diamine chelate rings, arising from co-crystallisation of enantiomers.

Ionic liquid crystals from β-diketonyl containing pyridinium cations and tetrachlorozincate anions

In this work, an approach towards ionic liquid crystals is strategically designed. A pyridine group has been attached to an 1,3-diketone containing an alkyloxyphenyl R substituent (R=C6H4OCnH2n+1; n=10–18) and protonated with hydrochloric acid towards the formation of the chloride salts of 2-[3-(4-n-alkyloxyphenyl)propane-1,3-dion-1-yl]pyridinium cations [OOR(n)py]Cl (I), which have been proved to be non-mesomorphic. Reaction of these organic–inorganic compounds (I) with ZnCl2 yields to the ionic liquid crystals of the type bis{2-[3-(4-n-alkyloxyphenyl)propane-1,3-dion-1-yl]pyridinium}tetrachlorozincate [OOR(n)py]2[ZnCl4] (II).The crystalline structure of compounds [OOR(12)py]Cl and [OOR(10)py]2[ZnCl4] as representative examples of both kinds of salts have been solved and discussed. Both compounds exhibit layered structures containing cationic and anionic sublayers. In addition for the tetrachlorozincate salt [OOR(16)py]2[ZnCl4] structural relationships between the mesophases and the crystalline phase are proposed on the basis of the variable-temperature small-angle X-ray diffraction studies.

Atom Transfer Radical Additions with the Cationic Half‐Sandwich Complex [Cp*Ru(PPh3)2(CH3CN)]OTf.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Atom Transfer Radical Additions with the Cationic Half‐Sandwich Complex [Cp*Ru(PPh3)2(CH3CN)]OTf

AbstractThe cationic ruthenium half‐sandwich complex [Cp*Ru(PPh3)2(CH3CN)][OTf] (2) (Cp* = η5‐C5Me5, OTf = SO3CF3) was synthesized by reduction of [Cp*RuCl2]2 with zinc in the presence of NaOTf and subsequent reaction with PPh3. When NaOTf was omitted, the corresponding tetrachlorozincate salts were obtained. Complex 2, as well as the salts [Cp*Ru(CH3CN)3]2[ZnCl4] (3) and [Cp*Ru(PPh3)2(CH3CN)]2[ZnCl4] (4), were characterized by single‐crystal X‐ray analysis. Complex 2 proved to be a potent catalyst for the atom transfer radical addition of CCl4 and CHCl3 to terminal olefins, displaying a performance superior to that of the previously described neutral catalyst [Cp*RuCl(PPh3)2]. For the addition of CHCl3 to styrene, a total turnover number of 890 was achieved. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Synthesis, characterization and DFT studies of the cobalt(III) complex of a tetrapodal pentadentate N4S donor ligand.

The synthesis of the pentadentate ligand 2,6-bis(3,3-dimethyl-2,4-dioxocyclohexanyl)-4-thiaheptane (N4Samp) is described. The synthetic pathway involves the coupling of two 1,3-(dimethylenedioxy)-2-methyl-2-(methylene-p-toluenesulfonyl)propane moieties with sodium sulfide and subsequent synthetic elaboration to prepare the final N4S donor system. The cobalt(III) complex [Co(N4Samp)Cl]2+ has been prepared and subsequently crystallized as the tetrachlorozincate salt. The X-ray structure analysis confirms the pentadentate nature of the ligand and shows the thioether donor occupying one apex with four equivalent amine donors effectively occupying the equatorial plane of the molecule. The sixth coordination site is occupied by a chloro ligand. The electronic absorption and 13C NMR spectra have been studied. DFT calculations have been employed to explore structural and mechanistic comparisons between [Co(N4Samp)Cl]2+ and an analogous pentaaamine complex.

Preparation and Photochemistry of Some Cobalt(III) Complexes of Tridentate Oxime-Diamine and Oxime-Amino Acid Ligands

Cobalt(III) complexes of tridentate ligands containing oxime-diamine and oxime-amino acid donor sets have been prepared, both by reduction of the related imine complexes. Many of the complexes have been characterized by X-ray crystallographic techniques. The photochemistry of these complexes has been studied. The oxime-diamine systems are rather unreactive, undergoing slow isomerization before decomposition. The oxime-amino acid systems appear to undergo decarboxylation reactions. Photolyses of tetrachlorozincate salts of some of the complexes result in binuclear species in which a trichlorozinc moiety is bound to the cobalt species through an oxime oxygen atom.

Synthesis and crystal structure of two stereochemical isomers of the trans-dichloro(1,4,8,11-tetraazacyclotetradecane)chromium(III) cation

Two stereoisomers of the cationic trans-[Cr(cyclam)Cl2]+ complex (cyclam = 1,4,8,11-tetraazacyclotetradecane) were prepared and isolated as the nitrate and tetrachlorozincate salts and their structures determined by X-ray diffraction studies of the monoclinic crystals of the nitrate salt, a= 6.480(2), b= 18.862(12), c= 13.628(6)Å, β= 100.28(3)°, and tetragonal crystals for the tetrachlorozincate salt, a= 16.377(4), c= 6.821(2)Å. The two complexes show an octahedral geometry about the metal atoms with the RSSR configuration but with differences in the conformations of the six-membered rings.

Transition-metal complexes with aliphatic Schiff bases. Part VIII. Isomeric hexamethyl-1,4,8,11-tetra-azacyclotetradecadienenickel(II) complexes formed by reaction of trisdiaminoethanenickel(II) with acetone

The nickel(II) complex of the quadridentate heterocycle hexamethyl-1,4,8,11-tetra-azacyclotetradecadiene [formed by reaction of trisdiaminoethanenickel(II) with acetone] occurs in two non-interconvertible isomeric forms, considered due to cis and trans arrangements of the heterocycle ring components. One of these isomers occurs as two inter-convertible forms, considered to be conformational isomers stabilized by steric hindrance. The perchlorate and tetrachlorozincate salts of the three isomers are described.