Sodium hydrogen bis­(phenoxy­acetate)

In the title compound, Na⁺·H⁺·2C₈H₇O₃⁻, the anion contains a short Speakman-type hydrogen bond [O⃛O = 2.413 (2) Å]. The anions and the Na atoms lie across twofold axes.     

Hydro­gen bonds in the framework of bis{2-[bis(2-amino­ethyl)­amino]­ethanol}nickel(II) diperchlorate

The title molecule, [Ni(C₆H₁₇N₃O)₂](ClO₄)₂, possesses a crystallographic centre of symmetry at the Ni^II position. The coordination geometry around the Ni^II atom is distorted octahedral, consisting of six N atoms from two tripodal poly­amine ligands, while the ethanol O atoms of the ligands remain uncoordinated. The crystal packing shows two-dimensional layers and an infinite three-dimensional framework which is stabilized by a hydrogen-bonded network.     

Di­chloro­bis(4-methyl­pentan-2-onato-C4,O)­tin(IV) and bis(4-methyl­pentan-2-onato-C4,O)(2-thio­xo-1,3-di­thiole-4,5-di­thiol­ato-S,S′)­tin(IV) at 150 K

The structures of the ketotins determined here, [SnCl₂(C₆H₁₁O)₂] and [Sn(C₃S₅)(C₆H₁₁O)₂], respectively, along with that previously reported for [MeC(O)CH₂CMe₂]₂SnI₂, are compared with the structures of the analogous estertins [MeOC(O)CH₂CH₂]₂SnX₂. Pairwise comparison of the mean ketotin [estertin] Sn—X and Sn—O distances as Sn—X 2.4422 (4) [2.4054 (7) Å], 2.4970 (4) [2.471 (2) Å] and 2.8463 (4) [2.7788 (8) Å] and Sn—O 2.4926 (12) [2.528 (1) Å], 2.6110 (11) [2.629 (7) Å] and 2.435 (3) [2.525 (4) Å] (for X = Cl, S and I, respectively) clearly demonstrates the superior donor ability of the ketotin O atom in chelate formation.     

trans-Bis(2-amino­pyridine-N)bis(O,O′-diiso­propyl di­thio­phosphato-S,S′)nickel(II)

In the title compound, [Ni(C₆H₁₄O₂PS₂)₂(C₅H₆N₂)₂], the coordination around the Ni atom, which lies on a crystallographic centre of symmetry, is octahedral with the S atoms from the di­thio­phosphate ligands occupying the equatorial positions, while the axial positions are occupied by the ring N atoms of the 2-amino­pyridine ligands. The mol­ecules form layers in the bc plane which are stacked in the direction of the a axis.     

catena-Poly[[trans-di­chloro­copper(II)]-μ-1,4,7,10,13,16-hexa­thia­cyclo­octa­decane-S1:S10]

In the title complex, [CuCl₂(C₁₂H₂₄S₆)]_n, the CuCl₂ unit and the ligand lie on and about inversion centres, respectively. The coordination geometry at Cu^II is a tetragonally elongated octahedron with the equatorial positions occupied by two chlorides, Cu—Cl 2.2786 (12) Å, and two S donors, Cu—S 2.3710 (13) Å. The apical positions of the octahedron are defined by two S donors at distances of 2.8261 (14) Å from the metal. The macrocyclic ligand adopts a very puckered and distorted conformation. Eight of the 18 torsion angles are less than 90° and all S-donors are oriented exo to the ring.     

Tri­carbonyl­[1,1′,1′′-ethyl­idyne­tris­(pyrazole-κN2)]­rhenium(I) bromide and tri­carbonyl­[methyl­idyne­tris­(pyrazole-κN2)]­rhenium(I) iodide ethanol hemisolvate

The two title compounds, [Re(C₁₀H₁₀N₆)(CO)₃]Br and [Re(C₁₁H₁₂N₆)(CO)₃]I·0.5C₂H₆O, have slightly distorted octahedral geometries about the rhenium centers. The distortions result from the constraints of the η³-coordinated tris­(pyrazol-1-yl)­methane ligands in each case which reduce the N—Re—N bond angles well below the preferred value of 90° for facially disposed ligands at a six-coordinate metal center.     

A trinuclear bis(dioximate)(chloro)(nitrosyl)ruthenium(II) complex containing two (2,2′-bipyridine)copper(II) groups

A trinuclear bis(cyclohexanedioximate)(chloro)(nitrosyl)ruthenium(II) complex containing two (2,2-bipyridine)-copper(II) groups has been synthesized and its electronic and electrochemical properties investigated. According to ZINDO/S calculations, the electronic structure of the ruthenium(dioximate)(nitrosyl) moiety is strongly delocalized. The electrochemical behavior has been interpreted with the aid of spectroelectrochemical measurements. In the trinuclear complex, it has been shown that the copper(II) ions can promote the oxidation of the NO species generated electrochemically, and also mediate the redox reactions of the complex, under a dioxygen atmosphere.     

Vapor- and mechanical-grinding-triggered color and luminescence switches for bis(σ-fluorophenylacetylide) platinum(II) complexes

Square-planar bis(σ-fluorophenylacetylide) platinum(II) complexes [Pt(Me(3)SiC≡CbpyC≡C-SiMe(3))(C≡CC(6)H(4)F)(2)] (C≡CC(6)H(4)F-2 for 2, C≡CC(6)H(4)F-3 for 3, and C≡CC(6)H(4)F-4 for 4; Me(3)SiC≡CbpyC≡CSiMe(3)=5,5'-bis(trimethylsilylethynyl)-2,2'-bipyridine) were prepared and were characterized by spectroscopic and luminescence studies, and X-ray crystallography. The color and luminescence of crystalline complex 3 is specifically sensitive to CHCl(3) vapor to afford 140-180 nm of luminescence vapochromic redshift, which is useful for specific detection of CHCl(3) vapor. Complex 4 displays selective luminescence vapochromic properties to CH(2)Cl(2) and CHCl(3) vapors with a luminescence vapochromic shift response of ca. 150-200 nm. Interestingly, complexes 2-4 exhibit reversible, and naked-eye perceivable, mechanical stimuli-responsive color and luminescence changes. When solid species 2-4 are crushed gently or ground, the crystalline state is converted to an amorphous phase. Meanwhile, bright yellow-orange luminescence in the crystalline species is converted to dark red under UV light irradiation with 100-160 nm of mechanochromic shift response. A vapochromic or mechanochromic cycle was monitored by dynamic variations in emission spectra and X-ray diffraction (XRD) patterns. The halohydrocarbon vapor- or mechanical-grinding-triggered color and luminescence switches are most likely correlated to a shorted intermolecular Pt-Pt distance as that revealed in vapochromic species 4·0.5 CH(2)Cl(2) by X-ray crystallography, thus leading to an increased contribution from intermolecular Pt-Pt interaction as demonstrated by DTF computational studies.     

N,N′-(1,2-phenylene)bis­(pyridine-2-carboxamide) and N,N′-(1,2-cyclohexanediyl)bis(pyridine-2-carbox­amide) toluene hemisolvate

The crystal structures of N,N′-(1,2-phenyl­ene)­bis­(pyridine-2-carbox­amide), C₁₈H₁₄N₄O₂, (I), and N,N′-(1,2-cyclo­hexane­diyl)­bis­(pyridine-2-carbox­amide) have been determined, the latter compound as the toluene hemisolvate, C₁₈H₂₀N₄O₂·0.5C₇H₈, (II). In (I), the benzene ring is nearly coplanar with one of the pyridine rings and forms a dihedral angle of 59.4 (1)° with the other. However, in (II), the dihedral angle of the two pyridine rings is 70.0 (1)°.     

Cyclometalated platinum(II) complexes as topoisomerase IIα poisons

A platinum(II)-based major groove binder [Pt(II)(C^N)(C≡NR)(2)](+) (HC^N = 2-phenylpyridine (phpy), R = 2-naphthyl) was identified as a potent human topoisomerase IIα poison. It stabilizes the covalent TopoIIα-DNA cleavage complex and induces cancer cell death with potency significantly higher than the widely clinically used TopoIIα poison Vp-16.     

Dimerization of terminal alkynes catalyzed by chloro(η-pentadienyl) bis(triphenylphosphine)ruthenium(II) and kinetics of phosphine substitution

Exchange of PMe₂Ph for PPh₃ in (η⁵-pentadienyl)ruthenium{bis(triphenylphosphine)}chloride, (η⁵-C₅H₇)Ru(PPh₃)₂Cl (1) under first order conditions proceeds rapidly in THF at room temperature. A pseudo-first order rate constant of 17 ± 2 × 10⁻⁴ s⁻¹ is obtained for the reaction at 21 °C. The rate constant is essentially independent of the phosphine concentration. The activation parameters, ΔH^† = 16.1 ± 0.4 kcal mol⁻¹ and ΔS^† = −16 ± 1 cal K⁻¹ mol⁻¹ differ from those reported for phosphine exchange in CpRu(PPh₃)₂Cl (2) and (η⁵-indenyl)Ru(PPh₃)₂Cl (3). The reaction of 1 with PMe₂Ph is about 70 times faster than the reaction of 2 at 30 °C and some 40 times faster than the reaction of 3 at 20 °C. (η⁵-C₅H₇)Ru(PPh₃)₂Cl(1) is more active than the ruthenium(II) complexes 2, 3, and TpRu(PPh₃)₂Cl (4) in the catalytic dimerization of terminal alkynes with nearly quantitative conversion of PhCCH and FcCCH at ambient temperature in 24 h. The enhanced substitution rate is accompanied by >50% conversion of phenylacetylene to oligomeric products. Reaction of 1 with NaPF₆ in acetonitrile yields the cationic ruthenium(II) complex [(η⁵-C₅H₇)Ru(PPh₃)₂(CH₃CN)][PF₆] (7). The latter complex is much less active in reactions with phenylacetylene than 1 but avoids the formation of oligomeric products.     

Bis(O,O′-diiso­propyl di­thio­phosphato-S,S′)(1,10-phenanthroline-N,N′)metal(II) complexes with cadmium(II) and iron(II)

The two title compounds, [M(C₆H₁₄O₂PS₂)₂(C₁₂H₈N₂)], where M = Cd^II and Fe^II, are isomorphous. Each compound has a crystallographic twofold axis of symmetry through the metal atom and the 1,10-phenanthroline mol­ecule. The central metal atom is coordinated to four S atoms from the two dithiophos­phate groups and two N atoms from the 1,10-phenanthroline ligand. The environment of the metal atom is a distorted octahedron.     

Palladium(II) and platinum(II)-C(3)-substituted 2,2′-bipyridines

Reaction of Pd(OAc)₂ with HL¹ and HL² (HL¹=6-iso-propyl-2,2-bipyridine; HL²=6-neo-pentyl-2,2-bipyridine), followed by treatment with LiCl or KI, gives [PdCl(L¹)]₂, (1), [PdCl(L²)]₂ (2), and [PdI(L²)]₂ (3), respectively. The chloride bridge in complexes1 and2 is split by PPh³ to give the mononuclear species PdCl(L¹)(PPh₃) (4) and PdCl(L²)(PPh₃) (5). Spectroscopic data provide evidence for coordination of the deprotonated ligands through a nitrogen and the C₍₃₎ atom of the 6-substituted pyridine. An analogous platinum complex PtCl(L³)(SMe₂) (6) (HL³=6-tert-butyl-2,2-bipyridine) was obtained from trans-PtClMe(SMe₂)₂ and HL³. The crystal structures of compounds1 and6 have been solved by X-ray diffraction analysis.Dipartimento di Chimica, Universita di Sassari, via Vienna 2, I-07100 Sassari, Italy; Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Universita di Milano, Centro CNR, I-20133 Milano, Italy; Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1127–1137, August, 1999.     

A linear cyclic oximate-bridged ­tetracopper(II) complex

The crystal structure of the title complex, tetrakis­[μ-6-amino-3-methyl-4-aza­hex-3-en-2-one oximato(1–)-κ⁴N,N′,N′′:O]tetracopper(II) tetraperchlorate 0.6-hydrate, [Cu₄(C₆H₁₂N₃O)₄](ClO₄)₄·0.6H₂O, shows the cation to be an oximate-bridged tetramer composed of four 6-amino-3-methyl-4-aza­hex-3-en-2-one oxime ligands and four copper(II) ions and to have crystallographically imposed symmetry. Each Cu^II atom is four-coordinated by the three N atoms of one oxime ligand and by the O atom of another oxime ligand in a distorted square-planar geometry.     

Bi- and terpyridyl platinum(II) chloro complexes: molecular catalysts for the photogeneration of hydrogen from water or simply precursors for colloidal platinum?

Platinum(II) bi- and terpyridyl chloro complexes, Pt(dcbpy)Cl2 and [Pt(ttpy)Cl]+, where dcbpy = 4,4'-dicarboxyl-2,2'-bipyridine and ttpy = 4-tolyl-2,2':6',2'-terpyridine, are used to investigate the nature of the active catalyst for the photocatalytic production of hydrogen from water. In a Pt(II) chloro system that contains a sacrificial electron donor, either MeOH or triethanolamine (TEOA), and titanium dioxide (TiO2) as an electron relay, sizable amounts of H2 can be observed upon UV bandgap irradiation. The quantity of H2 can be significantly reduced in the presence of mercury under the same conditions. Using a known sensitizer, [Pt(ttpy)(phenylacetylide)]+ (1), combined with a Pt(II) chloro complex in a similar system, there is a substantial induction period until the evolution of H2, under visible light (lambda > 410 nm) irradiation. It is suggested that the Pt(II) chloro complexes are simply acting as precursors to Pt colloids that function as the H2 generating catalyst     

Di­bromo{N-[2-(di­phenyl­phosphino)­benzyl­idene]-2,6-diiso­propyl­aniline-κ2N,P}nickel

In the title compound, [NiBr₂(C₃₁H₃₂NP)], (I), the second reported example of a nickel–imino­phosphine N,P-chelate in which the Ni atom has tetrahedral coordination, the Ni coordination is distorted as a consequence of the N—Ni—P chelate bite angle of 91.07 (6)° compensated by the Br—­Ni—­Br angle of 126.385 (18)°. In (I) and its analogue, viz. dichloro{[2-(4-isobutyloxazol-2-yl)phenyl]diphenylphos­phine-N,P}nickel(II), the Ni—N and Ni—P distances are greater and the N—Ni—P ligand bite angles smaller than those observed in a series of related complexes with square-planar nickel.     

A new polymorph of barium chloro­anilate trihydrate

Single crystals of a new polymorph of the title compound, barium(II) 3,6-di­chloro-2,5-di­hydroxy-1,4-benzo­quinone tri­hydrate, Ba²⁺·C₆Cl₂O₄²⁻·3H₂O, have been grown in sodium metasilicate gel. Each Ba²⁺ cation is coordinated by eight O atoms. The Ba²⁺ cations are bridged by an O atom of a ligand around the centre of symmetry at Wyckoff position 4a and by the O atom of a water mol­ecule around the centre of symmetry at Wyckoff position 4b, forming a sheet parallel to the (100) plane. Loose contacts are found around one of the water mol­ecules, as observed in the Cmca form.     

A nitronyl nitro­xide complex of ­nickel(II) with nitrate as a ligand

The complex cation in [4,5-di­hydro-4,4,5,5-tetra­methyl-2-(2-pyridyl-κN)­imidazol-1-oxyl 3-oxide-κO³](nitrato-κ²O,O′)(N,N,N′,N′-tetra­methyl-1,2-ethanedi­am­ine-κ²N,N′)­nickel(II) hexafluorophosphate dichloromethane solvate, [Ni(NO₃)(C₆H₁₆N₂)(C₁₂H₁₆N₃O₂)]PF₆·CH₂Cl₂, is the first example of a nitro­nyl nitro­xide complex of a transition metal ion having d electrons in which nitrate is coordinated as a bidentate ligand. Owing to the smaller steric requirement of NO₃⁻, the Ni—­O(nitro­xide) bond length [2.014 (2) Å] is remarkably shorter than that in the corresponding ­β-­diketonate complexes [2.052 (4)–2.056 (2) Å].     

A ferric-cyanide-bridged one-dimensional dirhodium complex with (18-­crown-6)­potassium cations

The crystal structure of the title compound, catena-poly[bis[aqua(18-crown-6)­potassium] di­aqua(18-crown-6)­potassium [[tetra-μ-benzoato-2:3κ⁸O:O′-μ-cyano-1:2κ²C:N-tetra­cyano-1κC-irondirhodium(Rh—Rh)]-μ-cyano-1κC:3′κN] octahydrate], [K(18-crown-6)(H₂O)]₂[K(18-crown-6)(H₂O)₂]­[FeRh₂(C₇H₅O₂)₄(CN)₆]·8H₂O, where (18-crown-6) is 1,4,7,10,13,16-hexaoxa­cyclo­octa­decane (C₁₂H₂₄O₆), has been determined. Ferric cyanides connect the dirhodium units to form a one-dimensional chain compound. [K(18-crown-6-ether)(H₂O)₂] cations (with inversion symmetry) and [K(18-crown-6-ether)(H₂O)] cations (in general positions) are located between the chains.     

EPR on bis(1,2-dithiosquarato)cuprate(II) in the bis(1,2-dithiosquarato)nickelate(II) host lattice — structure and spectroscopy‡

EPR spectroscopy is a well suited analytical tool to monitor the electronic situation around paramagnetic metal centres as copper(II) and therefore the structural influences on the paramagnetic ion. 1,2-Dithiosquaratometalates are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. Synthesis and characterisation of bis(benzyltributylammonium)1,2-dithiosquaratonickelate(II), (BzlBu₃N)₂[Ni(dtsq)₂], and bis(benzyltributylammonium)1,2-dithiosquaratocuprate(II), (BzlBu₃N)₂[Cu(dtsq)₂], with benzyltributylammonium as the counter ion is reported and the X-ray structures of two complexes, (BzlBu₃N)₂[Ni(dtsq)₂] and (BzlBu₃N)₂[Cu(dtsq)₂], are presented. Both complexes, crystallising in the monoclinic space group P2₁/c, are isostructural with only small differences in the coordination sphere due to the different metal ions. The diamagnetic nickel complex is therefore well suited as a host lattice for the paramagnetic Cu(II) complex to measure EPR for additional structural information.