L. Naldini

Bis(triphenylphosphine)pyridine- and pyrazine-carboxylatecopper(I) complexes

Abstract Several complexes obtained by the reactions of tetrahydroboratebis(triphenylphosphine)copper(I) with pyridine(py)- and pyrazine(pyz)-carboxylic acids have been obtained and characterized by infrared spectra. Crystal structures of the L 2 Cu(3-py(CO 2 )) and the L 2 Cu(2,3-py(CO 2 )(COOH)) (L = triphenylphosphine) complexes have been determined. The L 2 CU(3-py(CO 2 )) complex has a polymeric structure in which each copper(I) atom is tetrahedrally coordinated to two molecules of triphenylphosphine and two nicotinate anions, one of which is bonded through the nitrogen atom and the other through the carboxylate group. The L 2 Cu(2,3-py(CO 2 )(COOH)) complex consists of tetrahedral monomeric units, in which the anion is coordinated through the nitrogen atom and unidentate ortho carboxylate group. The structures of the other complexes are proposed on the basis of their analytical and infrared data.

Synthesis and X-ray structure of [CuPPh3CCPh]4, an electron deficient molecule with μ-bridging phenylacetylide ligands

Abstract The [CuPPh3CCPh]4 tetramer, obtained by treatment of [Cu(PPh3)2BH4] with phenylacetylene and KOH (molar ratio 1/1/1) in 1/1 benzene/benzyl alcohol, consists of a tetrahedral skeleton of metal atoms bonded to four terminal phosphine molecules and to four μ-3 -bridging phenylacetylide ligands which behave essentially as 2e donors.

An XPS and Auger study of some polynuclear copper compounds

An XPS and Auger characterization of the electronic structure of some polynuclear copper compounds is reported. The core level photoelectron spectra, the Cu(L3VV) Auger lines and the Auger parameters are discussed in terms of both the different coordination environments in the studied copper compounds and of the polarizability of the ligands.

Metal complexes of 2,4-diamino-5-(3′,4′,5′-trimethoxybenzyl)pyrimidine, (trimethoprim). Part II. Synthesis, magnetic characterization and X-ray structure of [Cu2(O2CCH3)4(trimethoprim)2]·2C6H6·CH3OH

Abstract The reaction of [Cu 2 (O 2 CCH 3 ) 4 ·2H 2 O] with trimethoprim is reported. In methanol a green solution was obtained, which, on adding benzene, yielded tetrakis(μ-acetato)bis(trimethoprim)dicopper(II) di-benzene methanol solvate. The compound crystallizes with four molecules per cell in the monoclinic space group C2/c, with a = 24.109(5), b = 15.256(3), c = 16.532(3) A, β = 116.89(2) for λ(Mo-Kα) = 0.71073 A. The copper atoms are bridged by four acetate groups to form the binuclear molecule [Cu 2 -(O 2 CCH 3 ) 4 (TMP) 2 ]·2C 6 H 6 ·CH 3 OH. The TMP ligand acts as a donor molecule through one pyrimidinic nitrogen atom.

Metal complexes of 2,4-diamino-5-(3′,4′,5′-trimethoxybenzyl)pyrimidine (trimethoprim) and 2,4-diamino-5-(p-chlorophenyl)-6-ethylpyrimidine (pyrimethamine). Part III. Syntheses and x-ray structures of [Rh2(O2CCH3)4(trimethoprim)2]·2C6H6·CH3OH and [Rh2(O2CCH3)4(pyrimethamine)2]

Abstract The syntheses and structures of [Rh 2 (O 2 CCH 3 ) 4 - Trim 2 ]· 2 C 6 H 6 ·CH 3 OH ( 1 ) and [Rh 2 (O 2 CCH 3 ) 4 - Pyr 2 ] ( 2 ) are reported. Compound 1 crystallizes in the monoclinic space group C 2/ c with a = 24.135- (5), b = 15.196(14), c = 16.536(3) A, β = 116.85(2)° and Z = 4. The Trim ligands coordinate the two axial positions of the dirhodium tetraacetato moiety through the pyrimidinic nitrogen N(1) with a Rh N(1) bond length of 2.289(2) A. Compound 2 is monoclinic, space group C 2/ m with a = 24.200(6), b = 10.295(3), c = 7.474(2) A, β = 90.61(3)° and Z = 2. The coordination of the Pyr ligands occurs via the pyrimidinic nitrogen N(3) with a RhN(3) distance of 2.365(3) A. In both complexes the RhRh interaction is 2.409(1) A.

METAL COMPLEXES OF CIMETIDINE. SYNTHESIS, X-RAY STRUCTURE DETERMINATION AND SEMIEMPIRICAL CALCULATIONS ON THE CIMETIDINATECOPPER(II)+ CATION

Abstract The addition of a methanolic solution of cimetidine (1) to a methanolic solution of M2+ cations (M = Co, NJ, Cu, Zn) affords the cationic complexes [M(1)2]2+. In the case of M = Cu the addition of KOH in the reaction medium at 60 °C gives the [Cu(2′)]+ cation, where 2′ is an anionic ligand resulting from deprotonation of a cimetidine molecule modified by methanolic solvolysis of the nitrilic function. The X-ray structure characterization of [Cu(2′)]X·0.5H2O has been performed for X = ClO4− (5) and I− (6). Compound 5 is monoclinic, space group C2/c with a=20.732(8), b=7.471(3), c=23.734(5) A, β 100.76(3)°, Z=8, R=0.034, Rw=0.045 for 1767 reflections with I>3σ(I). Compound 6 is monoclinic, space group C2/c with a=20.736(3), b=7.426(3), c=22.786(2) A, β=99.65(1)°, Z=8, R=0.029, Rw=0.045 for 2498 reflections with I>3σ(I). In both compounds the 2′ anion acts as a tetradentate ligand coiled around the almost square planar metal center. Quantomechanical semiempirical calculations (CNDO/ 2) have been carried out on simple models of 2′, 5 and 6.

A new class of gold cluster compounds. Synthesis and X-ray structure of the octakis(triphenylphosphinegold) dializarinsulphonate, [Au8(PPh3)8](aliz)2

[Au9L8]3+(L = PPh3) reacts with L to give the new dication [Au8L8]2+; an X-ray analysis of [Au8(PPh3)8](aliz)2(aliz = alizarinsulphonate) shows that the central gold atom, while still displaying the usual short interactions with all the peripheral metal atoms, is no longer confined in an entirely metallic cage, but is also directly bonded to a phosphine ligand.

Synthesis, NMR study, and X-ray structure of 2-(N-methyl-N′-cyano-N″-ethylguanidino) thiotriophenylphosphinegold(I)

The reaction between cimetidine in a methanolic solution of KOH and a dichloromethane solution of PPh3AuCl affords a new compound with formula [L-Au-PPh3] (I) (L = 2-(N-methyl-N′-cyano-N″-ethylguanidino)thiolate), the thiolato ligand resulting from cleavage of one of the thioether bonds of cimetidine. (I) has been characterized by elemental analysis, infrared, and 1H and 13C NMR spectroscopy. Single crystal x-ray structure determination shows that the gold atom is linearly coordinated by a phosphine ligand (Au-P 2.258(1) A) and by an S atom (Au-S 2.282(1) A) of the thiolato ligand. Crystal data: triclinic, space group P1 with a = 8.848(1), b = 11.343(3), c = 12.107(3)A, α = 87.63(1), β = 85.24(1), γ = 79.89(1)°, R = 0.024 for 3673 reflections with I > 3 δ (I).

Preparation and structure of the hexakis(tris-p-tolylphosphinegold) salt of tetraphenylborate and electronic structure of gold cluster compounds

The structure of the [AuPAr3]62+ cation is reported and an interpretation of the electronics of gold cluster compounds is proposed; the latter is parallel to current interpretations for boranes, carboranes and metalcarbonyl clusters.