cis‐Dichloro(dimethyl sulfoxide‐S)(2‐methoxypyridine‐N)platinum(II)

The title complex, [PtCl₂(C₆H₇NO)(C₂H₆OS)], exhibits square‐planar geometry. The plane of the pyridine ring makes a dihedral angle of 67.2 (3)° with the square plane of the metal center. The S—O bond is nearly aligned with the adjacent Pt—N bond, leaving the methyl groups of the di­methyl sulfoxide ligand to stagger the Pt—Cl bond.     

trans‐Dichloro(dimethyl sulfide‐κS)(pyridine‐κN)platinum(II)

The structure of the title compound, [PtCl₂(C₅H₅N)(C₂H₆S)], consists of discrete mol­ecules in which the Pt‐atom coordination is slightly distorted square planar. The Cl atoms are trans to each other, with a Cl—Pt—Cl angle of 176.60 (7)°. The pyridine ligand is rotated 64.5 (2)° from the Pt square plane and one of the Pt—Cl bonds essentially bisects the C—S—C angle of the di­methyl sulfide ligand. In the crystal structure, there are extensive weak C—H⋯Cl interactions, the shortest of which connects mol­ecules into centrosymmetric dimers. A comparison of the structural trans influence on Pt—S and Pt—­N distances for PtS(CH₃)₂ and Pt(pyridine) fragments, respectively, in square‐planar Pt^II complexes is presented.     

cis‐Bis(3,6‐di­hydro‐2H‐1,2‐oxazine‐N)­di­iodo­platinum(II) and cis‐bis(3,4,5,6‐tetra­hydro‐2H‐1,2‐oxazine‐N)­di­iodo­platinum(II)

The title complexes, [Pt(C₄H₇NO)₂I₂], (I), and [Pt(C₄H₉NO)₂I₂], (II), possess similar square‐planar coordination geometries with modest distortions from ideality. For (I), the cis‐L—Pt—L angles are in the range 87.0 (4)–94.2 (3)°, while the trans angles are 174.4 (3) and 176.4 (3)°. For (II), cis‐L—Pt—L are 86.1 (8)–94.2 (6)° and trans‐L—Pt—L are 174.4 (6) and 177.4 (5)°. One 3,6‐di­hydro‐2H‐1,2‐oxazine ligand in (I) is rotated so that the N—O bond is out of the square plane by approximately 70°, while the N—C bond is only ca 20° out of the plane. The other oxazine ligand is rotated so that the N—C bond is about 80° out of the plane, while the N—O bond is out of the plane by approximately 24°. In (II), the 3,4,5,6‐tetra­hydro‐2H‐1,2‐oxazine ligands are also positioned with one having the N—O bond further out of the plane and the other having the N—C bond positioned in that fashion. Both ligands, however, are rotated approximately 90° compared with their positions in (I). In both complexes, this results in an unsymmetrical distortion of the I—Pt—N bond angles in which one is expanded and the other contracted. These features are compared to those of reported cis‐di­amine­di­iodo­platinum(II) complexes.     

trans‐(2‐Acetylpyridine‐κ2N,O)dichlorobis(dimethyl sulfoxide‐κS)ruthenium(II)

In the title complex, [RuCl₂(C₇H₇NO)(C₂H₆OS)₂], the metal ion is at the centre of a distorted octahedral NOCl₂S₂ coordination sphere. The neutral 2‐acetyl­pyridine ligand binds to the metal ion through the pyridine N and carbonyl O atoms, forming a five‐membered chelate ring. The monodentate S‐coordinating di­methyl sulfoxide mol­ecules are mutually cis, and the two remaining positions in the coordination sphere are occupied by two mutually trans Cl^? ions.     

cis‐Bis(acetato‐κO)bis(dimethyl sulfide‐κS)platinum(II)

The title compound, cis‐[Pt(CH₃COO)₂(C₂H₆S)₂], crystallizes in the P2₁/c space group with a pseudo‐square‐planar coordination geometry. The complex forms centrosymmetric dimeric packing units, with C—H...O—Pt interactions and a short Pt...Pt distance [3.5868 (2) Å]. The coordination mode of the acetate ligands is monodentate and they are oriented almost perpendicular to the coordination plane. Cambridge Structural Database [Allen (2002). Acta Cryst. B 58 , 380–388] data show a preferred staggered conformation with respect to the coordination plane for Me₂S in complexes with Pt^II.     

Dibromido(dimethyl sulfoxide‐κO)(1,10‐phenanthroline‐κ2N,N′)copper(II)

The solvent effect on the molecular structures of copper(II) complexes produced from the reaction between CuBr₂ and 1,10‐phenanthroline is evident. The momomeric title compound, [CuBr₂(C₁₂H₈N₂)(C₂H₆OS)], which consists of discrete units, is produced from this reaction in dimethyl sulfoxide (DMSO), whereas a polymeric copper(II) compound is known to be produced from the same reaction in the poor coordinating solvent ethanol. The geometry around the copper(II) ion in the title compound is best described as trigonal–bipyramidal distorted square‐based pyramidal, with a τ value of 0.37. The two phenanthroline N atoms, the DMSO O atom and one of the Br atoms occupy the four basal positions, while the second Br atom occupies the axial position. The magnetic susceptibility data also indicate that the title compound is monomeric, but there is still a weak antiferromagnetic interaction between paramagnetic copper(II) centers via the intermolecular `Cu—Br...Br—Cu' contact pathway.     

(S)‐trans‐Cyclohexane‐1,2‐dicarboximide

The molecule of the title compound, C₈H₁₁NO₂, contains a strained bicyclic system with a significantly twisted imide chromophore. The five‐membered ring fragment containing the imide function is strongly puckered and adopts a half‐chair conformation. The six‐membered ring has a slightly distorted chair conformation. The mol­ecules are joined by strong N—H?O and weak C—H?O hydrogen bonds into infinite chains.     

Bis(dimethyl sulfoxide‐S)tetrakis(μ‐p‐hydroxybenzoato‐O:O′)dirhodium(II)–tetrakis(μ‐butyrato‐O:O′)bis(dimethyl sulfoxide‐S)dirhodium(II) cocrystal ethanol disolvate

The title structure, [Rh₂(C₇H₅O₃)₄(C₂H₆OS)₂]·[Rh₂(C₄H₇­O₂)₄(C₂H₆OS)₂]·2C₂H₆O, contains two discrete neutral Rh–Rh dimers cocrystallized as the ethanol disolvate. Each dimer is situated on an inversion center. The butyrate chain displays disorder in one C‐atom position. In each dimer, the di­methyl sulfoxide ligand (dmso) is bound via S, as expected. The ethanol is a hydrogen‐bond acceptor for one p‐hydroxy­benzoate hydroxyl group and acts as a hydrogen‐bond donor to the dmso O atom of a neighboring p‐hydroxy­benzoate dirhodium complex. A third hydrogen bond is formed from the other p‐hydroxy­benzoate hydroxyl group to the dmso O atom of a butyrate–dirhodium complex.     

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.     

Kinetics and mechanism of the interaction of adenosine with cis‐diaqua(cis‐1,2‐diaminocyclohexane)platinum(II) perchlorate in aqueous medium

The kinetics of the interaction of adenosine with cis‐[Pt(cis‐dach)(OH₂)₂]²⁺ (dach = diaminocyclohexane) was studied spectrophotometrically as a function of [cis‐[Pt(cis‐dach)(OH₂)₂]²⁺], [adenosine], and temperature at a particular pH (4.0), where the substrate complex exists predominantly as the diaqua species and the ligand adenosine exists as a neutral molecule. The substitution reaction shows two consecutive steps: the first is the ligand‐assisted anation followed by a chelation step. The activation parameters for both the steps have been evaluated using Eyring equation. The low negative value of ΔH^≠₁ (43.1 ± 1.3 kJ mol^?1) and the large negative value of ΔS^≠₁ (?177 ± 4 J K^?1 mol^?1) along with ΔH^≠₂ (47.9 ± 1.8 kJ mol^?1) and ΔS^≠₂ (?181 ± 6 J K^?1 mol^?1) indicate an associative mode of activation for both the aqua ligand substitution processes. The kinetic study was substantiated by infrared and electrospray ionization mass spectroscopic analysis. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 219–229, 2011     

A First Approach to the cis‐trans‐cis‐Photocyclodimers of 1,2‐Naphthoquinone

On irradiation (λ=350 nm), 1,2‐naphthoquinone (=naphthalene‐1,2‐dione) monoacetals 1 are converted quantitatively to mixtures of the cis‐trans‐cis‐photocyclodimers 2 and 3 . Careful hydrolysis of each of the (parent) pentacyclic diacetals 2a and 3a affords the – rather unstable – compounds 4 and 5 , respectively.     

cis‐Dichloridobis(diethyl sulfide‐κS)platinum(II) at 295 and 150 K

The title compound, cis‐[PtCl₂(C₄H₁₀S)₂], crystallizes in the space group P2₁/n with pseudo‐square‐planar coordination geometry. The orientation of the ethyl groups on the S atoms is staggered with respect to the coordination plane, giving the complex approximate C_2v symmetry. The complex does not form dimeric packing units with short Pt...S intradimeric distances as seen in some related complexes, but instead displays C—H...Cl interactions in three dimensions. These C—H...Cl—Pt contacts are compared with those of related compounds reported in the Cambridge Structural Database, which show a frequency maximum in the range 120–170° for the C—H...Cl angle.     

Platinum complexes of oxopurines: cis‐bis(theophyllinato‐N7)bis(triphenylphosphine)platinum(II) and cis‐chloro(theobrominato‐N1)bis(triphenylphosphine)platinum(II) ethanol hemisolvate

The syntheses and structures of two mixed‐ligand complexes of platinum(II) with deprotonated oxopurine bases and tri­phenyl­phosphine are reported, namely the theophyllinate complex cis‐bis(1,2,3,6‐tetra­hydro‐1,3‐di­methyl­purine‐2,6‐dionato‐κN⁷)­bis(tri­phenyl­phosphine‐κP)­platinum(II), [Pt(C₇H₇N₄O₂)₂(C₁₈H₁₅P)₂], (I), and the theobrominate complex cis‐chloro(1,2,3,6‐tetrahydro‐3,7‐dimethylpurine‐2,6‐dionato‐κN¹)­bis(tri­phenyl­phosphine‐κP)­platinum(II) ethanol hemisolvate, [PtCl(C₇H₇N₄O₂)(C₁₈H₁₅P)₂]·0.5C₂H₅OH, (II). In (I), the coordination geometry of Pt is square planar, formed by the two coordinating N atoms of the theophyl­linate anions in a cis arrangement and two P atoms from the tri­phenyl­phosphine groups. In (II), there are two crystallographically independent mol­ecules. They both exhibit a square‐planar coordination geometry around Pt involving one Cl atom, the coordinating N atom of the theobrominate anion and two P atoms from the tri­phenyl­phosphine groups. The two tri­phenyl­phosphine groups are arranged in a cis configuration in both structures. The heterocyclic rings are rotated with respect to the coordination plane of the metal by 82.99 (8) and 88.09 (8)° in complex (I), and by 85.91 (16) and 88.14 (18)° in complex (II). Both structures are stabilized by intramolecular stacking interactions involving the purine rings and the phenyl rings of adjacent tri­phenyl­phosphine moieties.     

Dichloro(4,4′‐dinonyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II)

The title compound, [PtCl₂(C₂₈H₄₄N₂)], is a new square‐planar Pt^II complex con­taining a bi­pyridine moiety with two long alkyl‐chain substituents. The complex forms a segregated packing structure made up of the alkyl‐chain layers and paired coordination sites.     

trans‐Di­chloro‐cis‐bis(3,6‐di­methyl­carbazolyl)‐cis‐bis­(tetra­hydro­furan)­zirconium(IV) benzene sesquisolvate

In the title compound, [ZrCl₂(C₁₄H₁₂N)₂(C₄H₈O)₂]·1.5C₆H₆, the Zr atom is pseudo‐octahedral, with two Cl atoms in trans positions and two tetra­hydro­furan mol­ecules in cis positions. The two 3,6‐di­methyl­carbazolyl ligands are in cis positions and are canted with respect to one another. The two Zr—N distances are 2.1148 (18) and 2.1236 (18) Å, and the N—Zr—N angle is 95.08 (7)°. The title compound crystallizes as the benzene solvate, with one of the benzene mol­ecules positioned on an inversion center.     

Synthesis and structural characterization of syndiotactic trans‐1,2 and cis‐1,2 polyhexadienes

The (E) isomer in mixtures of (E) and (Z) 1,3‐hexadiene was polymerized with the system CoCl₂(PⁱPrPh₂)₂‐MAO, a highly active and stereospecific catalyst for the preparation of 1,2 syndiotactic polybutadiene. A new crystalline polymer with a melting point of 109 °C was obtained. The polymer was characterized by IR, NMR (¹³C, ¹H in solution and ¹³C in the solid‐state), X‐ray diffraction, DSC, GPC and it was found to have a trans‐1,2 syndiotactic structure with a 5.18 ± 0.04 Å fiber periodicity. Since only the (E) isomer was polymerized, at the end of the reaction we were able to separate the (Z) isomer, which was ultimately polymerized with CpTiCl₃‐MAO at low temperature, obtaining a low molecular weight, stereoregular polymer that, characterized by IR and NMR methods, was found to exhibit a cis‐1,2 syndiotactic structure, never reported before. Molecular mechanics calculations were carried out on the trans‐1,2 syndiotactic polymer and structural models consistent with the X‐ray diffraction data are proposed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5339–5353, 2007     

cis‐Bis(dimethyl sulfide)dinitratoplatinum(II) at 295 and 150 K

The title compound, [Pt(NO₃)₂(C₂H₆S)₂], crystallizes in the P2₁/n space group (Z′ = 2), with pseudo‐square‐planar coordination geometry. The complex forms dimers with pseudosymmetry C_i arranged in columns along the b‐axis direction, with Pt...Pt distances of 6.3056 (3) and 4.2382 (2) Å (at 150 K). Each column is surrounded by six other columns in a honeycomb rod‐like packing. The coordination mode of the nitrate ligands is monodentate, with Pt—O—N angles ranging from ∼117 to ∼118° and a tilt between the nitrate ligands and the coordination planes in the range ∼63–70° (at 150 K). The coordination mode of the nitrate ligands is compared with that observed in reported Pt(NO₃)₂L₂ complexes (where L is a ligand with a donor atom from group 15 or 16), all of which are monodentate, with an average Pt—O—N angle of 118 (2)° and a tilt in the range 90 ± 30° (with two exceptions, in which the nitrates are approximately in the coordination plane).     

trans‐Bis(hexafluoroantimonato)(phthalocyaninato)copper(II)

The title compound, trans‐bis­(hexa­fluoro­antimonato‐F)(phthalocyaninato‐κ⁴N^29,30,31,32)copper(II), [Cu(SbF₆)₂(C₃₂­H₁₆N₈)] or Cu(pc)(SbF₆)₂ (pc is phthalocyaninate), comprises a six‐coordinate Cu atom, lying on an inversion center, bonded to four N atoms of a phthalocyanine ring and to F atoms of two trans SbF₆^? groups. The compound is presumed to consist of a Cu^II center and a doubly oxidized phthalocyanine ring, by analogy with Cu(pc)(ReO₄)₂.     

trans‐Bis(3‐acetyl­pyridine‐κN)diiodoplatinum(II)

In the square‐planar title complex, [PtI₂(C₇H₇NO)₂], the Pt atom lies on a crystallographic inversion center, coinciding with an anti arrangement of the 3‐acetyl­pyridine ligands. The dihedral angles between the pyridine rings and the Pt coordination plane are 67.5 (2)°, while those between the pyridine rings and the acetyl planes are 20.8 (5)°. The ¹⁹⁵Pt NMR resonance of the title complex (CD₂Cl₂) was observed at −3224 p.p.m. The major structural parameters are compared with those from previously reported related structures.