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Weakly coordinated [Cu(pcp)(H2O)n] complexes are formed in aqueous solution, at room temperature, by interaction of P,P'-diphenylmethylene diphosphinic acid (H2pcp) with copper(II) ions. However, heating of the solutions gives rise to the formation of two extended metal-oxygen networks of formulas [Cu(pcp)(H2O)2] x H2O, 1, and [Cu(pcp)(H2O)2], 2. In the presence of 2,2'-bipyridyl (bipy) the diamine derivative [Cu(pcp)(bipy)(H2O)], 4, has been isolated. Complex 1 easily loses water to form a monohydrated derivative [Cu(pcp)H2O], 3, whereas 2 is completely dehydrated after prolonged heating at 150 degrees C, under vacuum. The compounds 1 and 2 have substantially different solid-state structures as shown by X-ray powder diffraction spectra, IR spectra, and thermogravimetric analyses. Consistently, the two complexes cannot be directly interconverted and present different dehydration pathways. Rehydration of these materials in both cases allows quantitative formation of 1. X-ray analysis established that the structure of 1 consists of a corrugated two-dimensional layered polymeric array, where infinite zigzag chains of Cu centers and bridging phenylphosphinate ligands are linked together through strong hydrogen-bonding interactions; the structure of 4 consists of monodimensional polymers, where the hydrogen-bonding interactions play an essential bridging role in the extended architecture. In both structures the metal center displays a five-coordinate environment with approximate square pyramidal geometry, with the pcp ligand acting as bidentate and monodentate in 1 and solely as bidentate in 4. In 1 the coordination sphere is completed through water molecules; in 4, through water and diamine ligands. The thermogravimetric analyses of the complexes are compared with those of the related hybrids [M(pcp)(H2O)3] x H2O, where M = Mn, Co, or Ni, confirming that noncoordinated water molecules also play a basic role in determining the molecular packing.

The synthesis, 9Be NMR spectrum, and molecular structure of the [Be3(μ-OH)3(H2O)6]3+ picrate salt are presented.

Four heterocycles containing hydroxy and keto functionalities have been tested as chelating agents of beryllium(II). These are in the order (i) 3-hydroxy-2-methyl-4H-pyran-4-one (maltol, Hma), (ii) 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one (kojic acid, Hka), (iii) 3-hydroxy-1,2-dimethyl-4-pyridinone (Hdpp), (iv) 1-(3-hydroxy-2-furanyl)ethanone (isomaltol, Hima). Although the skeletons of the first three species, with one nitrogen or oxygen heteroatom at the six-membered ring, are almost superimposable, straightforward synthesis and crystallization is achieved only for the 1:2 adduct Be(dpp)(2), 1. Also the complex Be(ima)(2), 2, precipitates in high yield but the ima(-) ligand has a different skeletal structure. X-ray determinations of 1 and 2 showed that the Be(2+) ion is pseudotetrahedrally coordinated by two chelating ligands with slightly asymmetric Be-O(alkoxo) and Be-O(keto) bonds. The complex Be(ma)(2) precipitates in low yields together with large amounts of unreacted Hma while, under the same conditions, no trace of the analogous species Be(ka)(2) has been observed. This paper presents the results of potentiometric and NMR studies in the aqueous solutions as well as of DFT structural optimizations for all of the free acids, their associated bases, and the adducts of the type [BeL(H(2)O)(2)](+) and BeL(2) in the gas phase. It is consistently found that the basicity of the ligands and the stability of their complexes decrease in the order dpp(-)ma(-)ka(-)ima(-). In solution, all of the anionic ligands form adducts of the type [BeL(H(2)O)(2)](+) at low pH values, whereas higher concentrations of the free anion are required to form 1:2 adducts. The pH, the basicity, and the stability constants of the complexes as well as the formation of competing beryllium hydroxide species are strictly correlated factors for the obtainment of the latter type of adduct. The DFT calculations account nicely for the different donor powers of the various chelates in terms of electronic redistribution and associated energetics.

L'hydrure [(np 3 ) NiH] BPh 4 (np 3 = tris (diphenylphosphino)-2 ethyl) amine reagit avec CO pour donner [(Hnp 3 ) NiCO] BPh 4 , etudie par RX

[Fe(P 4 )Br] BPh 4 •CH 2 Cl 2 avec P 4 =hexaphenyl tetraphospha-1, 4, 7, 10 decane cristallise dans P1 avec Z=2; affinement jusqu'a R=0,079 (etude a 150 K). Discussion egalement de la variation du moment magnetique entre 86 et 376 K

[Co(Ph 2 PCH 2 P(Ph) 2 P 4 P(Ph) 2 CH 2 PPh 2 )]BF 4 cristallise dans le systeme monoclinique, groupe d'espace P2 1/n et sa structure est affinee jusqu'a R=0,063 {[Co(Ph 2 PCH 2 P(Ph) 2 P 4 P(Ph) 2 CH 2 PPh 2 )] [W(CO) 5 ]}BPh 4 cristallise dans P2 1/a

The complex [(triphos)CO(μ-N 3 )] 2 (BPh 4 ) 2 •2(CH 3 ) 2 CO, triphos=CH 3 C(CH 2 PPh 2 ) 3 crystallizes in the triclinic system, space group P136, with a=18.122 (9) A, b=14.025 (8) A, c=12.668 (7) A, α=92.95 (8)˚, β=103.77 (9)˚, and γ=108.12 (8)˚. The molecular structure consists of discrete dinuclear [(triphos)Co(μ-N 3 )] 2 2+ cations with the cobalt atoms in a distorted P 3 N 2 square-pyramidal environment. The compound is diamagnetic, and the observed diamagnetic has been related to the low-symmetry mixing of d x 2 -y 2 orbitals of cobalt with the ground d z 2 orbitals by using extended Huckel calculations

Die l : 1:1-molare Umsetzung von [Co(OH2)6 ](BF4)2 mit Et3P.CS2 und 1,1,1-Tris-[diphenylphosphinomethyH-ethan fuhrt abhangig von den Reaktionsbe- dingungen zu unterschiedlichen Produkten.

Cristallisation dans le systeme monoclinique, groupe P2 1 et affinement de la structure jusqu'a R=0,047. Coordination tetraedrique autour des atomes Co. Discussion sur l'influence de l'etat fondamental triplet de la molecule sur une stereochimie particuliere