Inorganic Chemistry Communications (v.4, #1)

Two novel low-dimensional framework materials, [Ni(en)2]2[Ni(en)2 Mo VI 6 V VI 10 O 40(V IV O 4)]·4H 2 O (1) and [en]0.5[Cu(en)2]2[Cu(en)2 Mo VI 6 Mo V 2 V IV 8 O 40(Mo IV O 4)]·0.5H 2 O (2), assembled hydrothermally, are constructed from the mixed Mo/V tetra-capped Keggin structure clusters linked through M(en)2(M=Ni,Cu) groups.
Keywords: Crystal structures; One- and two-dimensional frameworks; The mixed Mo/V tetra-capped Keggin structure clusters; Linked through M(en)2(M = Ni,Cu) groups;

Synthesis of a novel voltammetrically active isopolyoxotungstate anion, [H6W18O60]6− by Sadayuki Himeno; Mayumi Yoshihara; Masahiko Maekawa (5-8).
A novel voltammetrically active isopolyoxotungstate anion, [H6W18O60]6− was prepared as a tetrapropylammonium (n-Pr4N+) salt from a freshly prepared solution (pH 4.0) of 500 mM ( M=mol dm −3) W(VI) at ambient temperature. The [H6W18O60]6− complex was obtained as a transient intermediate in the transformation of [W10O32]4− into α-[H2W12O40]6−, and the formation conditions were elucidated in relation to those of [W10O32]4− and α-[H2W12O40]6−. The [H6W18O60]6− complex was characterized by 183 W NMR and voltammetric behaviors.
Keywords: Isopolyoxotungstate; Formation conditions; [H6W18O60]6-; Voltammetry;

Silver complexes with large crown ethers in propylene carbonate by H.-J. Buschmann; A. Wego; E. Schollmeyer (9-11).
The complex formation between large crown ethers – e.g. dibenzo-30-crown-10 – and Ag+ in propylene carbonate has been studied using potentiometric and calorimetric titrations. The values of the reaction enthalpies with larger crown ethers than 18-crown-6 especially with dibenzo-30-crown-10 indicate that more than six donor atoms are taking part in the interaction with the complexed cation. The values of the reaction entropies of the largest crown ethers examined indicate the high sterical requirements of the complex formation. Obviously large crown ethers are able to encapsulate the complexed cation. The effectiveness of the encapsulation however depends upon the ring size and flexibility of the crown ethers.
Keywords: Crown ethers; Silver(I) complexes; Potentiometry; Calorimetry;

Lanthanide(III) complexes of a highly efficient actinide(III) extracting agent – 2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine by Michael G.B. Drew; Denis Guillaneux; Michael J. Hudson; Peter B. Iveson; Mark L. Russell; Charles Madic (12-15).
The addition of lanthanide(III) nitrates (Sm–Lu) to the actinide(III) extracting agent – 2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (L1) in a 1:1 ratio results in the crystallisation of complexes containing [Ln(L1)3]3+ moieties and a variety of anions.
Keywords: Lanthanides; Actinides; Extraction; Nuclear reprocessing;

Dirhodium(II) carboxylate complexes as building blocks. Synthesis of dimeric species as connectors for macrocycles by Richard P. Bonar-Law; Thomas D. McGrath; Jamie F. Bickley; Cristina Femoni; Alexander Steiner (16-18).
Two complexes of the form (AcO)2Rh2LRh2(OAc)2 in which two Rh2 4+ units are covalently linked have been prepared by reaction of Rh2(OAc)4 with bischelating tetracarboxylate ligand L=( O 2 CC(Me)2 O))2 PhPh(OC(CH 3)2 CO 2 )2 in N,N-dimethylaniline. A crystal structure of the major (kinetic) product showed, unexpectedly, that it contained two 14 membered chelate rings, with the isomeric minor (thermodynamic) product having two 12 membered chelate rings.
Keywords: Dirhodium tetracarboxylates; Dimers; Chelates; Macrocycles; Crystal structure;

Rhodium wires based on binuclear acetate-bridged complexes by Florian P. Pruchnik; Piotr Jakimowicz; Zbigniew Ciunik; Kamil Stanislawek; Luis A. Oro; Cristina Tejel; Miguel A. Ciriano (19-22).
The synthesis, properties, structure and conductivity of a new class of one-dimensional, mixed valence Rh(I)–Rh(II) complexes {Rh 2(μ-O 2 CMe)2(N–N)2][BX 4]}n  (N–N =bipyridine, phenanthroline; X=F, Ph) are described.
Keywords: Metal wires; Nitrogen heterocycles; N ligands; Rhodium; Stacking interactions;

First complex containing a Pd22-NCPh2)2 functional group by José Ruiz; Venancio Rodrı́guez; Natalia Cutillas; Félix Florenciano; José Pérez; Gregorio López (23-25).
Synthesis of the azavinylidene-bridged compound anti-[{Pd(C6F5)(t-BuNC)(μ-NCPh2)}2] is described. The molecular structure reveals that the core of the molecule is formed by a Pd2N2 skeleton in a bent configuration.
Keywords: Palladium complexes; Azavinylidene (benzylideneamido) complexes; Crystal structure;

The crystal structure of first copper(II) complex of a pyridine-2-carboxamidrazone – a potential antitumor agent by Nikhil Gokhale; Subhash Padhye; Dan Rathbone; David Billington; Phillip Lowe; Carl Schwalbe; Chris Newton (26-29).
The crystal structure of the neutral, distorted square planar copper(II) complex, viz. cis-[dichloro (N1-(2-benzyloxybenzylidene) pyridine-2-carboxamidrazone) copper(II)] (1) is reported which is the first well-characterized copper(II) complex of the series (space group C2/c; a=18.414(5)  A ̊ ; b=8.6510(10)  A ̊ ; c=27.091(4)  A ̊ ; α=90°; β=109.800(17)°; γ=90°; R 1=0.0331 wR 2=0.0852). The distortion from square planar geometry is thought to arise from the non-equivalent ligand donor set. The Cu–Cl bonds are equivalent with one of the Cl atoms making intermolecular contact at 2.6070  A ̊ with adjacent copper rendering a pseudo-square pyramidal geometry around copper. The complex is further characterized by UV/VIS spectroscopy, electrochemistry and magnetic susceptibility measurements. The in vitro antitumor activity of this complex and the parent ligand is determined against the human breast cancer cell-line MCF-7 which revealed that copper complexation renders a highly antiproliferative compound with IC50 value of 3 μM.
Keywords: Carboxamidrazone; Copper complex; Antitumor activity; Breast cancer;

The temperature dependence of the emission lifetimes of two structural isomers of an osmium polypyridyl complex are reported. The compounds [Os(bpy)2(4,4-dcbpy)] (1) and [Os(bpy)2(3,5-dcbpy)] (2), where 4,4-dcbpy=4,4-dicarboxy-2,2-bipyridine and 3,5-dcbpy=3,5-dicarboxy-2,2-bipyridine, differ only in the placement of their two hydrophilic carboxylate groups within the unique bipyridine ligand. In argon-saturated water, the emission life-time of 1 decreases with increasing temperature and can be fit to the Arrhenius expression (k obs =k0   exp(−E a /RT)) to give values of k0=(2.6±0.3)×108   s −1 and E a =+330±20  cm −1 . In contrast the emission of 2 measured in ethanol displays longer lifetimes at higher temperatures to give k0=(2.9±0.3)×106   s −1 and E a =−590±20  cm −1 . Thus, the specific localization of the hydrophilic carboxylate groups in these molecules significantly alters their photophysical properties and can produce negatively activated emission lifetimes.
Keywords: Osmium; Polypyridine; Solvation; Non-radiative decay; Negative activation energy;

Synthesis and crystal structure of trans-nitrosoaquatetraammineruthenium(II) sulphate hydrosulphate, [Ru(NO)(NH3)4(H2O)](SO4)(HSO4) by V.A. Emel'yanov; A.V. Virovets; I.A. Baidina; S.A. Gromilov; A.V. Belyaev (33-35).
The reaction between [RuNO(NH3)4OH]Cl2 and an excess of 2 M H2SO4 leads to the protonation of the starting complex and crystallisation of the title complex with sulphate and hydrosulphate anions. The crystal structure of the product has been determined. The linear nitroso group and water molecule are coordinated in trans positions.
Keywords: Nitroso complex; Ammine complex; Ruthenium(II); Sulphate; Crystal structure;

The synthesis and spectroscopic characterization of three novel phosphorus(V) compounds, chiral at phosphorus, are reported. All three compounds were characterized by X-ray crystallography, and for one compound a 1H–31P HETCOR experiment was performed.
Keywords: Phosphorus; Sulfur; Nitrogen; Chiral; Imidodiphosphinates; Imidodiphosphates;

2D structure with rectangular grids woven by coordination chains and pseudo-metal wires by Hua-Xin Zhang; Bei-Sheng Kang; Liang-Rong Deng; Chen Ren; Cheng-Yong Su; Zhong-Ning Chen (41-44).
A heterometallic assembly, [{Cd(en)2Ag(CN)2}{Ag(CN)2}] n , has been synthesized and structurally characterized. The 2D layered structure is constructed by interweaving the coordination chains of {Cd(en)2Ag(CN)2}+ containing CdNCAg linkage with the pseudo-metal wires formed by the anions [Ag(CN)2] and Ag(I) of the chains through Ag–Ag interactions.
Keywords: Cyanide complex; Coordination polymer; Ag–Ag interactions; Metal wire;

The construction of enantio- and diastereomerically pure multinuclear RuII complexes by using enantiomerically pure chiral coordination complexes as chiral tridentate ligands provides a new strategy for the design of stereochemically defined supramolecular architectures.
Keywords: Ruthenium complexes; Enantiomer; Diastereomer; Supramolecular architectures;

A five co-ordinate platinum(II) complex containing the water soluble 1,3,5-triaza-7-phosphaadamantane ligand (PTA) [Pt(PTA)3(I)2] (1), was characterised in the solid state and aqueous solution. A re-calculation of the Tolman cone angle for the PTA ligand, as well as preliminary equilibrium constants for the formation of 1, is given.
Keywords: Five-coordinate platinum(II); Crystal structure; Water-soluble; PTA ligands; Tolman angle; Stability constants;

The complex formation between different crown ethers and the cryptand (2 2 2) with the ammonium and alkali ions was studied in chloroform as solvent using calorimetric titrations. From the reaction enthalpies for the complex formation with 18-crown-6 and the cryptand (2 2 2) as well as from competitive reactions between both ligands no influence of ion pairs can be detected within the experimental error. Stability constants of the complexes formed could only be obtained in case of the complex formation of Na+ with benzo-18-crown-6 and of Cs+ with most of the ligands.
Keywords: Crown ethers; Cryptand; Complexes; Chloroform;

Reactivity of [Ru3(μ-H)(μ-Me2pz)(CO)10] with 2,4-hexadiyne. Characterization of the first tetranuclear ynenyl complex by Javier A. Cabeza; Marta Moreno; Vı́ctor Riera; Marı́a de J. Rosales-Hoz (57-59).
The tetranuclear ynenyl complex [Ru4(μ-η2-Me2pz)(μ44-MeCHCCCMe)(μ-CO)(CO)10] (Me2pz=3,5-dimethylpyrazolate) has been prepared by reaction of [Ru3(μ-H)(μ-η2-Me2pz)(CO)10] with 2,4-hexadiyne and has been characterized by X-ray diffraction methods. It consists of an unusual broken-wing butterfly (spiked triangle) tetraruthenium framework (64-electron) with all the metal atoms bridged by a hex-2-yn-4-en-4-yl ligand (7-electron donor). This type of coordination is unprecedented for ynenyl ligands.
Keywords: Ruthenium clusters; Ynenyl ligands; Diynes; Pyrazolate ligands;

Density functional theory has been used to relate the intrinsic N2 binding affinities of the Fe and Mo sites of the iron–molybdenum cofactor of nitrogenase (FeMoco) to those of known N2 complexes. The results indicate that initial N2 binding to FeMoco is reversible, and that Mo is the preferred site. A mechanism for N2 reduction is proposed in which a partially reduced MoNNH2 species undergoes cleavage across a MoFeS2 face of FeMoco.
Keywords: Density functional theory; Molybdenum; Nitrogenase; Nitrogen fixation; Quantum calculations;