Inorganic Chemistry Communications (v.4, #12)

Announcing “Mini-Reviews” by Umberto Belluco; Daniel G. Nocera; Albert S.C. Chan (v).

In the presence of oxalate the trinuclear oxide-bridged complex [RuIII 3O(acetate)6(CH3OH)3]+ in methanol undergoes a photoreduction to the RuII/RuIII mixed-valence complex [Ru3O(acetate)6(CH3OH)3] with φ=0.01 and 5×10−4 at λ irr=366 and 546 nm, respectively. It is suggested that the photolysis is initiated by an oxalate to Ru(III) CT state.
Keywords: Electronic spectra; Charge transfer; Photochemistry; Ruthenium complexes;

MnIII(J-salen)Cl (Jacobsen catalyst) with J-salen=N,N -bis(3,5-di-tert.-butylsalicylidene)-1,2-diaminocyclohexane dianion in CHCl3 is photooxidized by the solvent to a MnIV(J-salen) complex, presumably MnIV(J-salen)Cl2, with φ=0.002 at λ irr =333  nm .
Keywords: Photochemistry; Salen complexes; Manganese complexes;

Assemblies based on trans-oxamidato-bridged copper(II) building blocks and the spacer succinate by Hua-Xin Zhang; Bei-Sheng Kang; Zhong-Yuan Zhou; Albert S.C. Chan; Kai-Bei Yu; Zhong-Ning Chen; Chen Ren (695-698).
Two compounds with the composition [Cu2(trans-L)(suc)(H2O)2] n ·2nH2O (L=oxap 1, oxen 2; suc=succinate) were obtained from the assembly of trans-oxamidato-bridged binuclear motif [Cu2(trans-L)]2+ and suc and their structures were determined by X-ray crystallography. Both compounds contain 1-D zigzag polymeric chains with the Cu(II) atoms alternately linked together by L and suc via covalent bonding interactions. Hydrogen-bonding interactions in them are abundant and very different. Their thermal properties were studied.
Keywords: Oxamidate complex; Coordination polymer; Succinate; Hydrogen-bonding interactions;

The hydrothermal synthesis and structure of a one-dimensional Fe(II)molybdophosphate by Yunshan Zhou; Lijuan Zhang; Xiaozeng You; Srinivasan Natarajan (699-704).
A new one-dimensional Fe(II)molybdophosphate of the formula, [(C10H8N2)H2]2[Fe4 (II)Mo12 (V)(HPO4)6(PO4)2(H2O)8(OH)6O24]·8H2O, (1), has been synthesized by employing hydrothermal methods and characterized by single crystal X-ray diffraction. The structure consists of a network of MO6 (M = Fe, Mo) octahedra and (H)PO4 tetrahedra linked through their vertices. The connectivity between the polyhedral units gives rise to one-dimensional chains with eight-membered apertures. The hydrogen bonded interactions between the chains form pseudo two-dimensional layers. Extensive hydrogen bonding also exists between the amine molecule, 4,4-bipyridine, water molecule and framework oxygen atoms. Crystal data for 1: monoclinic, space group = P21 (no. 4), a=12.549(3) (Å), b=23.496(5) (Å), c=14.551(3) (Å), β=114.87(3)°, V=3892.5(15)  A ̊ 3 , and Z=2.
Keywords: Hydrothermal synthesis; One-dimensional structure; Fe(II); Phosphate; Molecular structure;

Facile bromination can be carried out in concentrated solutions of zinc bromide (60–80% w/w ZnBr2 in water) [A. Ewenson, D. Itzhak, M. Freiberg-Bergstein, A. Shushan, B. Croitoru, D. Beneish, N. Faza, WO patent 99/19275, Bromine Compounds Ltd., Israel, 1999]. These brine solutions offer an alternative to expensive and harmful organic solvents. A correlation between the reactivity and the molecular ratio H2O:Zn has been found and quantified using UV-Vis spectroscopy [J.A. Duffy, G.L. Wood, J. Chem. Soc., Dalton Trans. (1987) 1485; E. Eyal, A. Treinin, J. Am. Chem. Soc. 86 (1964) 4287–4290; D. Meyerstein, A. Treinin, Trans. Faraday Soc. 59 (1963) 1114–1120]. Based on spectrophotometric and NMR results, it is proposed that these concentrated aqueous solutions, which behave similarly to anhydrous media, enhance the reactivity of molecular bromine by polarizing the Br–Br bond. Furthermore they affect the electron density distribution in the organic substrates.
Keywords: Zinc bromide; Electrophilic aromatic substitution;

Synthesis and characterization of the first poly(imidazolyl)borate organotin(IV) complex exhibiting a polymeric chain structure by M. Pellei; C. Pettinari; G. Gioia Lobbia; C. Santini; A. Drozdov; S. Troyanov (708-711).
The reaction between SnR n X4−n (R=Me, Ph or cy; n=2 or 3) acceptors and sodium tetrakis(imidazol-1-yl)borate, Na[B(im)4], yields {[B(im)4]R n SnCl4−n−1} compounds. The X-ray crystal structure of [μ-(im)2B(im)2SnMe3] is the first example of a polymeric derivative containing the [B(im)4] ligand coordinated in bridging fashion.
Keywords: Organotin(IV); Tetrakis(imidazolyl)borate ligand; Crystal structure;

A new alternating double aquo-bridged and single cyano-bridged polymeric complex {[Ba2(phen)4(H2O)6Fe(CN)6]·Cl·2(phen)·3H2O} n (1) (phen = 1,10-phenanthroline) has been synthesized and structurally characterized. In the crystal structure the two centrosymmetric [Ba2(phen)4(H2O)6] units are bridged through two trans CN groups of [Fe(CN)6]3− ion, which results in the formation of a zig-zag polymeric chain. In each [Ba2(phen)4(H2O)6] unit, the two Ba centers are joined by double aquo bridges. Both the Ba atoms are 9-coordinated with distorted mono-capped square antiprismatic geometry. An elaborate hydrogen bonding system holds the parallel polymeric chains together.
Keywords: Barium; Iron; Cyano-bridge; Phenanthroline; Crystal structure;

A new 3-D neutral metal–organic framework polymer, [Cu(NA)2] 1, has been synthesized under hydrothermal reaction conditions. The structure of 1 is self-assembled from binuclear square pyramidal copper(II) coordinated by multidentate nicotinato ligands.
Keywords: Coordination polymer; 3-D structure; Hydrothermal reaction; Binuclear copper; Square pyramidal; Copper nicotinate;

The presence of the two isomeric species (M and m) of Eu(III) (DOTA-like) complexes has been detected in aqueous solution by UV–Vis absorbance spectrophotometry. It shows that the 7 F 0  →  5 D 0 transition in Eu(III) complexes does not only depend on the coordinating atoms present in the first coordination sphere but that it may also be influenced by small differences in the coordination geometry. The absorbance spectra could be well fitted with the K=M/m equilibrium constants measured by NMR. The wavelength variation between the two isomers is found to be 0.20 nm (DTMA), 0.14 nm (DOTA) and about 0.25 nm (DOTAM) (DTMA=1,4,7,10-tetrakis-(methylcarbamoylmethyl)-1,4,7,10-tetraazacyclo-dodecane; DOTA=1,4,7,10-tetraaza-1,4,7,10-tetrakis(carboxymethyl)-cyclododecane; DOTAM=1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane). This is small enough not to affect the quantitative determination of water coordination equilibria in solution as hydration equilibria produce differences of about 0.5 nm.
Keywords: MRI contrast agents; Eu(III); UV–Vis; Solution equilibrium; Isomeric species;

The reaction of bis(diphenylphosphino)acetylene(DPPA) with Co2(CO)8 in toluene at 80 °C for 24 h resulted in an alkyne-bridged, diphosphine-chelated tetracobalt-complex, [Co2(CO)5{μ-P,P-(μ-PPh2CCPPh2)}][Co2(CO)4{μ-P-(μ-PPh2CCPPh2)}] 3. The X-ray structural studies of 3 reveals that it can be regarded as a dimerized form of two DPPA bridged dicobalt complex, [Co2(CO)6(μ-PPh2CCPPh2)] 1.
Keywords: Diphosphine ligand; Chelating ligand; Alkyne-bridged dicobalt-complex; Tetracobalt-complex;

Synthesis and structural characterization of new one-dimensional rhodium complexes by Florian P. Pruchnik; Piotr Jakimowicz; Zbigniew Ciunik (726-729).
New one-dimensional RhI–RhII complexes [Rh2(OOCMe)2(phen)2] n (PF6) n ·0.5nMe2CHOH, 1 and [Rh2(OOCMe)2(bpy)2] n (PF6) n ·nH2O, 2 have been synthesized and characterized. The compound 1 is molecular wire with the shortest Rh(I)–Rh(II) distances, anions and solvate molecules occupy channels between parallel cationic wires.
Keywords: Metal wires; Nitrogen heterocycles; N ligands; Rhodium; Stacking interactions;

Phenanthroline–manganese inclusion complexes of dicarboxylic acid containing extensive hydrogen-bonding interactions by Chengbing Ma; Wenguo Wang; Hongping Zhu; Changneng Chen; Qiutian Liu (730-733).
Two phenanthroline–manganese inclusion complexes with [MnCl(H2O)(phen)2]+ core were prepared in the presence of dicarboxylic acid and their structures were determined. Uncoordinated adipic acid and phthalic acid as guest molecules are included in the complexes with formulas {[MnCl(H2O)(phen)2]Cl}2·C6H10O4·8H2O (1) and {[MnCl(H2O)(phen)2]Cl}4·2C8H6O4·4H2O (2). The dicarboxylic acid molecules together with aqua and Cl ligands, Cl anions and solvate H2O molecules form extensive hydrogen-bonding interactions, building up supramolecule-like aggregate structure.Dicarboxylic acid is enclosed in the host structure of [(C12H8N2)MnCl(H2O)]+ to form two inclusion compounds containing adipic acid and phthalic acid, respectively. Extensive hydrogen-bonding interactions were observed.
Keywords: Manganese; Phenanthroline; Crystal structure; Dicarboxylic acid;

Photoluminescence characteristics of ZnS nanocrystallites co-doped with Co2+ and Cu2+ by Ping Yang; Mengkai Lü; Guangjun Zhou; DuoRong Yuan; Dong Xu (734-737).
Zinc sulfide (ZnS) nanoparticles co-doped with Cu2+ and Co2+ have been prepared by precipitation from homogeneous solutions of zinc, copper and cobalt salt compounds, with S2− as precipitating anion formed by decomposition of thioacetamide. X-ray diffraction shows that the average crystallite size of doped and undoped ZnS nanometer-scale samples is about 2–3 nm. Novel luminescence characteristics (strong and stable visible-light emission, λ em∼515–560 nm) have been observed for the co-doped ZnS nanocrystals at room temperature. The relative fluorescence intensity of the co-doped sample is dramatically higher than that of undoped ZnS nanocrystallites. The emission wavelength of the co-doped samples varies with change in the impurity mole ratio of Cu2+ and Co2+.
Keywords: ZnS nanocrystallites; Photoluminescence; Co-dope; Cu2+ and Co2+;

Irradiation of itaconatopentamminecobalt(III) perchlorate complex in the ligand to metal charge transfer absorption band in aqueous solution using 254 nm radiation produced an oxidised ligand free radical, which further reacts with itaconatopentamminecobalt(III) ion and also by radical dimerisation reaction to form a compound which shows broad absorption at ∼265 nm and emission at ∼425 nm. The compound is identified to be a derivative of itaconic acid. The photoproduct shows two lifetimes of 1.5±0.1 ns and 5.5±0.5 ns indicating that the photoproduct decomposes at room temperature to give a second compound which is also luminescent.
Keywords: Photochemistry; Itaconatopentamminecobalt(III) ion; Photoredox reaction; Luminescence;

Reactions of the ferrocene-phosphines FcPH2 and 1,1-Fc(PH2)2 with excess formaldehyde gives the new hydroxymethylphosphines FcP(CH2OH)2 1 and 1,1-Fc[P(CH2OH)2]2 2, respectively. Phosphine 1 is an air-stable crystalline solid, whereas 2 is isolated as an oil. Reaction of 1 with H2O2, S8 or Se gives the chalcogenide derivatives FcP(E)(CH2OH)2 (E=O, S or Se), whilst reaction of 2 with S8 gives 1,1-Fc[P(S)(CH2OH)2]2, which were fully characterised. Phosphine 1 was also characterised by an X-ray crystal structure determination.
Keywords: Ferrocene compounds; Hydroxymethylphosphines; Crystal structure; Phosphine chalcogenides;

The synthesis, structures and reactivity of unsymmetrical multiply-bonded dirhenium(IV,II) and dirhenium(III,II) complexes that contain the bis[2-(diphenylphosphino)phenyl]ether ligand ( L 1 ) are described, including the isolation and structural characterization of the novel terephthalate-bridged tetrarhenium complex [Re2Cl43- L 1)]2 (μ-O2CC6H4CO2) in which there is weak electronic coupling between the pairs of dirhenium centers.
Keywords: Dirhenium complexes; Multiple metal–metal bonds; Tridentate P,O,P ligand; Electronic coupling;

Structural characterisation of rac-bis(2,2-bipyridine)(2,5-dipyridylpyrazine)ruthenium(II) hexafluorophosphate; a key building block for metallodendrimers by Edwin C. Constable; Hans Eriksson; Catherine E. Housecroft; Benson M. Kariuki; Ebbe Nordlander; Jerry Olsson (749-752).
The complex [(bipy)2Ru(dpp)][PF6]2 which contains a vacant 2,2-bipyridine-like metal-binding domain has been structurally characterised. This compound is a key building block for the construction of metallodendrimers using the “complexes as metals, complexes as ligands” approach.
Keywords: 2,5-Dipyridylpyrazine; Ruthenium complex; Crystal structure; Metallodendrimers; Artificial photosynthesis;

Reaction of the ligand N,N,N ,N -bis[(2-hydroxybenzyl)(N-methylimidazolyl)]-2-ol-1,3-propendiamine (Hbhbmipo) with copper(II) perchlorate and sodium acetate in acetonitrile/ethanol leads to the assembly of a novel dinuclear copper(II) complex. The crystal structure, magnetic properties and its catecholase activity are reported. Both copper(II) ions are set in a distorted square pyramidal coordination sphere with a N2O3 donor set resulting in a Cu⋯Cu distance of 3.382(5) Å. To our knowledge this is the first example of a dinuclear Cu(II) complex with square pyramidal coordination geometry in which the N2O3 donor set contains N-imidazol and O-phenol. The complex represents a structural model for a tyrosine intermediate in the proposed mechanism during hydroxylation of monophenols.
Keywords: Crystal structure; Copper(II) complex; Model compound; Tyrosinase; Catecholase activity;

The reaction of 2,2-di(hydroxymethyl)biphenyl with (t-Bu)3Al leads to the formation of the bimetallic compound [(t-Bu)4Al2(HOCH2C12H8CH2O)2] (1) with two hydroxyl groups. The compound 1 has been characterized by 1H and 13C NMR spectroscopy, cryoscopic molecular weight measurements and elemental analysis and molecular structure has been confirmed by X-ray crystallography. The 18 membered cycle (Al2O4C12) of 1 adopts a configuration with endocyclic oxygen atoms that allow for the intra-molecular hydrogen bonding formation.
Keywords: Aluminium; 2,2-di(hydroxymethyl)biphenyl; Intra-molecular hydrogen bonding;

2-Aminopyrimidine (2-ampym) and 4-aminopyrimidine (4-ampym) coordinate to W(CO)5 predominantly via the exocyclic amino group (>91% in 10 min photolysis) rather than to the endocyclic N-1 position as found for 2-aminopyridine (2-ampy). Photolysis of W(CO)6 in acetone in the presence of these ligands forms amino-bound [W(CO)5(2-ampym)] and [W(CO)5(4-ampym)] complexes. Secondary photolysis generates 18% (1.0 h photolysis) [W(CO)4(2-ampym)] or [W(CO)4(4-ampym)], chelated via the exocyclic amine and the adjacent endocyclic position (N-1 and N-3, respectively). Only ca. 10% of the more unhindered N-1-bound W(CO)5(4-ampym) was detected compared to virtually complete coordination via the exocyclic amino group for [W(CO)5(2-ampym)]. Mmff94 calculations show that the W(CO)5 coordination to the exocyclic donor is favored by 98.8 and 95.6 kcal/mol over the adjacent endocyclic position in the 2-ampym and 4-ampym complexes, respectively. Calculated W–N bond lengths by the Mmff94 methods gave exo-amine W–N bond distances of 2.24 and 2.26 Å and theoretical adjacent endocyclic W–N bond distances of 2.37 and 2.35 Å (isomers not observed from photolysis) for the 2-ampym and 4-ampym complexes, respectively. A W–(N-1) bond of 2.28 Å for this isomer of [W(CO)5(4-ampym)] was calculated. All W–N bonds are near the 2.18–2.33 Å range (mean of 2.27±0.06) for [W(CO)5L] (L=pyridine, piperidine, glycine, 1-(2-py)-1,2,4-triazole, [W(CO)5CN], 5-MeU).

Diaquabis(4,4-bipyridine)copper(II) di(o-sulfobenzimidate) dichloromethane solvate, a two-dimensional Cu4(4,4-C5H4NC5H4N)4 rhombic grid clathrating guest dichloromethane by Panče Naumov; Gligor Jovanovski; John V. Hanna; Ibrahim Abdul Razak; Suchada Chantrapromma; Hoong-Kun Fun; Seik Weng Ng (766-768).
In the crystal structure of bis(4,4-bipyridine)diaquacopper(II) di(o-sulfobenzimidate) dichloromethane solvate, the host polycationic [Cu(4,4-C5H4NC5H4N)2(H2O)2] rhombic grids stack over each other 8.16 Å apart along the c-axis of the orthorhombic Pbcn unit cell. The Cu4(4,4-bpy)4 rhombus clathrating a disordered dichloromethane molecule has a copper atom at the corner and the spacer heterocycle with pyridyl rings twisted by 21.8(2)°, as its side. The anions occupy the space between the layers; the grids interact with each other indirectly through water–anion hydrogen bonds [O⋯O=2.766(4); O⋯N=3.061(4)  A ̊ ]. The structure sets a remarkable example of potentials born by the polyfunctional o-sulfobenzimidate moiety for construction of unusual architectures.
Keywords: Bipyridine; Clathrate; Host–guest complex; Saccharin; Spacers; X-ray diffraction;