Annabella Orlandini

Some rhodium(I) and rhodium(III) complexes with the tripod-like ligands RC(CH2PPh2)3 (R = Me: triphos; R = Et: triphos-I) and the X-ray crystal structure of [RhH3(triphos-I)]

Abstract The syntheses of [RhH3(triphos)] (8, triphos = CH3C(CH2PPh2)3) and the related compound [RhH3(triphos-I)] (triphos-I = EtC(CH2PPh2)3) are described, and the X-ray crystal structure of the latter is reported. The crystals are monoclinic space group P21/a, a 15.985(6), b 19.683(7), c 11.900(4) A, β 103.73(6)°, Z=4. The structure was solved by the heavy atom method and refined by full-matrix least-squares to the conventional R factor value of 0.057 for 2649 observed reflections. The metal atom is octahedrally coordinated by three phosphorus atoms and by three hydrogen atoms, each trans to one phosphorus. Complex 8 has been shown to react with CO to give [RhH(CO)(triphos)] (2). Compound 2 reacts with CH2=CHCO2Me to give only the branched insertion product [Rh(CH(CH3)CO2Me)(CO)(triphos)]. The complex [RhCl(CO)(triphos)] has been re-investigated and was obtained in a single isomeric form which has been assigned a five-coordinate structure. The five-coordinate compounds (RhX(CO)(triphos)] (X = Br and I) are also described.

Synthesis, properties and structures of the two “electron rich” cobalt-sulphur clusters [Co6(μ3-S)8(PEt3)6]1+,0

Abstract The reaction of hydrogen sulphide with [Co(H 2 O) 6 ](BF 4 ) 2 and triethylphosphine in the presence of sodium tetraphenylborate or tetrabutylammonium hexafluorophosphate gave the paramagnetic clusters [Co 6 (μ 3 -S) 8 (PEt 3 ) 6 ]( Y ) ( Y = BPh 4 , ( 1 ), PF 6 , ( 2 )). These compounds can be easily reduced by sodium napthalenide to the diamagnetic species [Co 6 (μ 3 -S) 8 (PEt 3 ) 6 ] · 2C 4 H 8 O ( 3 ). The molecular structures of 1 and 3 have been established by single-crystal X-ray diffraction methods. Crystal data: ( 1 ) space group P 1 , a = 19.481(9), b = 15.562(7), c = 12.390(b) A, α = 92.70(8), β = 94.50(7), γ = 94.10(9)°, Z = 2, ( 3 ) space group R 3 , a = 11.780(6) A, α = 92.50(7)°, Z = 1. Both structures were solved by the heavy atom method and refined by full-matrix least-squares techniques to the conventional R factors values of 0.050 for 1 and 0.044 for 3 on the basis of 4251 and 1918 observed reflections, respectively. The two clusters [Co 6 (μ 3 -S) 8 )(PEt 3 ) 6 ] 1+,0 are isostructural, the inner core consisting of an octahedron of cobalt atoms with all the faces symmetrically capped by triply bridging sulphur atoms. Each metal centre is additionally linked to a triethylphosphine group so that each cobalt atom is co-ordinated by four sulphur atoms and one phosphorus in a distorted square pyramidal environment. The addition of one electron whilst leaving unchanged the geometry of the inner framework, induces small changes in the structural parameters, the average CoCo and CoP distances being 2.794 (3) and 2.162 (2) A for 1 and 2.817 (3) and 2.138 (2) A for 3 respectively. Electrochemistry in non-aqueous solvents shows the electron-transfer sequence The tricationic species is stable only in the short time of cyclic voltammetric tests.

Preparative, potentiometric and NMR studies of the interaction of beryllium(II) with oxalate and malonate. X-ray structure of K3[Be3(OH)3(O2C–CH2–CO2)3]·6H2O

Abstract The complexes formed by beryllium(II) with the bidentate ligands oxalate, L=(O2C–CO2)2−, and malonate, L=(O2C–CH2–CO2)2−, have been investigated in aqueous solution using both potentiometric and 9Be NMR measurements. The species [BeL(H2O)2], [BeL2]2−, [Be3(OH)3L3]3− and [Be3(OH)3(H2O)3L]+ have been identified and their formation constants have been determined at 25°C in 0.5 mol dm−3 NaClO4. The malonate complexes are much more stable than the oxalate ones. New crystalline salts of formula K3[Be3(OH)3L3]·nH2O have been isolated using conditions established with the aid of speciation calculations. The structure of K3[Be3(OH)3(malonate)3]·6H2O has been determined by an X-ray structure analysis: orthorhombic, space group Pc21n, a=9.011(3), b=14.041(4), c=18.761(9) A, Z=4. Each beryllium atom is tetrahedrally coordinated by two hydroxo groups and two oxygen atoms from the chelating malonate. The (Be(OH))3 core is a puckered six-membered ring with each hydroxo group bridging two beryllium centres.

Organomercury derivatives of the 2,4,6-trimercaptotriazine (H3TMT). X-ray crystal structure of (HgMe)3(TMT)

Abstract By reaction of RHgCl with Na3(C3N3S3)·9H2O, organomercury derivatives of formulae (HgR)3(C3N3S3) (R=Me, Et), have been synthesized and characterized. The methyl-derivative has been completely studied by X-ray diffraction analysis. The crystal and molecular structure consists of discrete (HgMe)3(C3N3S3) units, where the triazine ligand is linked through the sulfur atoms to three HgMe moieties in a “manxane” arrangement.

Isolation of [Be3(μ-OH)3(H2O)6]3+. Synthesis, 9Be NMR Spectroscopy, and Crystal Structure of [Be3(μ-OH)3(H2O)6](picrate)3·6H2O

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

Reactivity of the triethylphosphinecarbon disulfide adduct Et3PCS2 toward iron(II) cations in the presence of the bis(tertiary phosphines), depe, and diphos, x-ray crystal structures of the complexes [(depe)2Fe(S2CPEt3)](BPh4)2 and [(depe)2Fe(S2CH)](BPh4)

Abstract Reaction of the triethylphosphinecarbon disulfide adduct Et 3 PCS 2 with iron(II) aquocations in the presence of the bis(tertiary phosphines) depe or diphos, and NaBPh 4 has given the monomeric complexes [(depe) 2 Fe(S 2 CPEt 3 )](BPh 4 ) 2 , 1 , and [(diphos)Fe(S 2 CPEt 3 ) 2 ](BPh 4 ) 2 · 0.5 (CH 3 ) 2 CO, 3 (depe = 1,2-bis(diethylphosphino)ethane; diphos = 1,2-bis(diphenylphosphino)ethane). Compound 1 undergoes nucleophilic attack by hydride ion on the coordinated Et 3 PCS 2 ligand to give the dithioformato derivative [(depe) 2 Fe(S 2 CH)](BPh 4 ), 2 . The structures of compounds 1 and 2 have been determined from counter diffraction X-ray data. Crystal data for 1 are: triclinic, space group P 1 , a 18.583(8), b 14.836(7), c 14.019(7) », α 94.38(4), β 102.56(4), γ 103.34(4)°, Z = 2, R = 0.080. Crystal data for 2 are: monoclinic, space group P 2 1 / a , a 28.912(10), b 11.949(6), c 13.386(7) », β 94.35(5)°, Z = 4, R = 0.076. In both structures the iron atom displays a distorted octahedral geometry, being linked to the phosphorus atoms of two depe molecules and to the two sulfur atoms of the zwitterion in compound 1 or of the dithioformato group in compound 2 .

A new lead(II) inorganic–organic hybrid of the P,P′-diphenylmethylene-diphosphinate ligand: synthesis and X-ray characterization of the [Pb(CH2(P(Ph)O2)2)] complex

Abstract By reaction of lead(II) nitrate with P,P′-diphenylmethylenediphosphinic acid in water solution a new inorganic–organic hybrid of formula [Pb(CH2(P(Ph)O2)2)] has been synthesized and structurally characterized. The complex displays a polymeric columnar structure, the column being formed by two intersecting sinusoidal ribbons of lead(II) ions bridged by bifunctional phosphinate ligands. The intersections of the ribbons are constituted by dimeric units of pentacoordinated lead(II) ions.

Isostructural organic–inorganic hybrids of P,P ′ -diphenyl-methylenediphosphinate (CH 2 (P(Ph)O 2 ) 2 ) 2− with divalent transition metals

Abstract New organic–inorganic hybrid materials have been synthesized by reaction in water solution of manganese, cobalt or nickel acetates with P,P′-diphenylmethylenediphosphinic acid and all the two-dimensional structure coordination polymers obtained have been found to be isomorphous.

A heterometallic ‘super-sandwich’ containing a novel hexagonal Cu6 unit at the centre: synthesis and X-ray structure determination of [{MeC(CH2PPh2)3}CoP3](CuBr)6[P3Co{(Ph2PCH2)3CMe}]·2CH2Cl2

The reaction of CuBr with [(triphos)CoP3][triphos = 1,1,1-tris(dipenylphosphinomethyl)ethane]gives [(triphos)CoP3](CuBr)6[P3Co(triphos)], which has been shown by a single crystal X-ray study to consist of two (triphos)CoP3 units held together by a hexagonal Cu6 fragment.

Facile reduction of carbon dioxide, carbonyl sulfide, and carbon disulfide by copper(I) borohydride. X-ray crystal structure of the complex [(triphos)Cu(O2CH)]

Abstract The copper(I)-borohydride complex [(triphos)Cu(BH4)] reacts with CO2, CS2, and COS under very mild conditions to give formate, dithioformate, or thioformate copper(I) complexes, respectively. A complete X-ray crystal structure determination has been carried out on the formate complex [(triphos)Cu(O2CH)].