R.A. Toscano

Abietane and icetexane diterpenoids from the roots of Salvia aspera

From the roots of Salvia aspera, two new icetexane diterpenoids (salviasperanol and 5,6-dihidro-6α-hydroxysalviasperanol) and one new abietane derivative (6-epi-demethylesquirolin D) were isolated in addition to the previously known diterpenoids sugiol, taxodione and demethylsalvicanol. The structures of the new compounds were established by spectroscopic means. An X-ray analysis was performed on salviasperanol.

Salvigenane and isosalvipuberulan diterpenoids from Salvia leucantha.

Abstract From the aerial parts of S. leucantha the rearranged neo-clerodane diterpenoid salvileucantholide was isolated. Its structure 1 was established by spectral means, chemical transformation and X-ray diffraction analysis. The salvigenane diterpenoid 4 and salvifaricin were also isolated from this source.

Synthesis, characterization and X-ray structure of stannocanes substituted with a cyclic dithiophosphate ligand X(CH2CH2S)2SnnBu [S2P(OCH2C(Et2)CH2O)], (X=O, S): a study about the conformational tendencies and the relationship with the anomeric effect of the stannocane rings

Abstract The preparation and conformational study of two stannocanes, 5-n-butyl-5-(5′,5′-diethyl-2′-thioxo-1′,3′,2′-dioxaphosphorinane-2′-thiolate)-1-oxa-4,6-dithia-5-stannocane, O(CH2CH2S)2SnnBu[S2P(OCH2CEt2CH2O)] (1) and 2-n-butyl-5-(5′5′-diethyl-2′-thioxo-1′,3′,2′-dioxaphosphorinane-2-thiolate)-1,3,6-trithia-2-stannocane S(CH2CH2S)2SnnBu[S2P(OCH2CEt2CH2O)] (2) is reported. These compounds were prepared from the corresponding chloro-oxa and -thia-stannocanes and the sodium salt of dithiophosphoric acid (2-mercapto-2-thiono-1,3,2-dioxaphosphorinane) in ethanol. Compounds 1 and 2 were characterized by IR, EI-MS and multinuclear NMR (1H, 13C, 31P). The molecular structures were determined by X-ray analyses. The eight-membered ring in both compounds has a boat–chair conformation with a 1,5 transannular Sn⋯O (2.468 A), Sn⋯S (2.94 A) interaction. The 1,3,2-dioxaphosphorinane ring in 1 and 2 present a chair conformation with the stannocane in the axial position, in accordance with the anomeric effect. The coordination of the Sn-atoms is trigonal-bipyramidal in 1 and intermediate between trigonal-bipyramidal and a bicapped tetrahedral arrangement in 2.

Synthesis and structural characterization of phenoxarsin-10-yl dithiocarbamates. O(C6H4) 2AsS2CN(CH2CH2)2, a compound containing an asymmetric mononuclear biconnective 1,1-dithiolato ligand

Abstract Phenoxarsin-10-yl dithiocarbamates O(C 6 H 4 ) 2 AsS 2 CX (X = NMe 2 , NEt 2 , N(CH 2 CH) 2 , N(CH 2 CH 2 ) 2 or CH(CH 3 )CH 2 ]) have been prepared by the reaction between O(C 6 H 4 ) 2 AsCl and sodium dithiocarbamates. The compounds were characterized by IR, mass and NMR ( 1 H and 13 C) spectroscopy. The molecular structure of O(C 6 H 4 ) 2 AsS 2 CN(CH 2 CH 2 ) 2 was determined using single-crystal X-ray diffraction. The compound is monomeric and contains an asymmetric monometallic biconnective dithiocarbamato unit (AsS(1), 2.277(1), A; As⋯S(2), 3.183(3) A). The double-bond character of the CN bond (1.318(5) A) is in agreement with the NMR data. The dihedral angle (155.2°) of the phenoxarsine moiety is almost unaffected by substitution of chlorine by the dithiocarbamato ligand.

Influence of the steric effect on the conformation of stannocanes. The synthesis and X-ray structure of X(CH2CH2S)2Sn(n-Bu)Cl (X=S, O)

Abstract 5-Chloro-5- n -butyl-1-oxa-4,6-dithia-5-stannocane ( 1 ) and 2-chloro-2- n -butyl-1,3,6-trithia-2-stannocane ( 2 ) have been prepared by reacting n -butyltin trichloride with 2-mercaptoethyl ether and 2-mercaptoethyl sulphide, respectively. Complexes 1 and 2 were characterised by elemental analyses, IR, EI MS, and multinuclear NMR ( 1 H, 13 C, 119 Sn). The molecular structures of 1 and 2 were determined by X-ray analyses. The eight-membered rings in both compounds are in the boat–chair conformation with a 1,5 transannular Sn⋯O (2.409(7) A) or Sn⋯S (2.7855(16) A) interaction. The coordination around the Sn atoms can be described as trigonal bipyramidal with Cl and X in the apical positions.

Synthesis and reactivity of aziridinocarbene complexes of chromium and tungsten: formation of nitrile and acetiminoester complexes

Abstract 2-Methylaziridine H NCH 2 C HCH 3 reacts with alkyl- and aryl-(alkoxy)carbene complexes of chromium and tungsten to give alkyl- and aryl-aziridinocarbene complexes. The latter undergo a thermal transformation to give olefins and alkyl- or aryl-nitrilechromium pentacarbonyl complexes, e.g. (CO) 5 CrNC- o -tolyl (which has been characterized by X-ray crystallography). 2-Phenylaziridine H NCH 2 C HPh in turn reacts with the carbene complexes to give directly styrene and the acetiminoester complexes (CO) 5 WHNC(CH 3 )OCH 2 CH 3 and (CO) 5 CrHNC(CH 3 )OCH 2 -CH 3 . The latter gives, upon hydrolysis (CO) 5 CrNH 3 . The structures of (CO) 5 WHNC(CH 3 )OCH 2 CH 3 and (CO) 5 CrNH 3 have been determined by X-ray diffraction. The mechanisms of the two reactions are discussed.

Synthesis, crystal and molecular structure of 2-methylthiosemicarbazide copper(II) nitrate, [Cu(2MeTSC)2(NO3)2]

Abstract The copper(II) complex of 2-methylthiosemicarbazide (2MeTSC) was obtained to evaluate the influence of the 2N-substitution on the structure and properties of thiosemicarbazide complexes. The crystal and molecular structures of [Cu(2MeTSC)2(NO3)2] were determined by single crystal X-ray diffraction. The complex is monomeric hexa-coordinated with a strongly tetragonally elongated octahedral structure. Two 2MeTSC groups coordinate to the metal ion as bidentate ligands through the hydrazinic nitrogen and the sulphur atom, determining a nearly square planar coordination. The fifth and sixth positions are occupied by oxygen atoms from two NO3− anions, at a long distance from the metal [ CuO = 2.864(3) A ]. The CuS [2.262(1) A] and CuN(3) [1.992(3) A] bond lengths are shorter than those observed in similar thiosemicarbazide copper(II) compounds, indicating a stronger bond. Another point of interest is the association of the complex units into a three-dimensional network through hydrogen bonding (O2NOHN).

Chloride Complexation with Thiosemicarbazone Metal Complexes. A Solid State Study

A solid state study of the chloride complexation ability of a series of salicylaldehyde thiosemicarbazone Ni(II) complexes is presented. Complexes of general formula [Ni(5-X-HSalTSC)PPh3]Cl, where 5-X-HSalTSC− represent the monoanion of 5-X-salicylaldhehyde thiosemicarbazones (with X = MeO, Br, NO2), were studied in comparison with the analog neutral complex [Ni(5-NO2-SalTSC)PPh3]. The crystal structure of the compounds show that the coordinated thiosemicarbazones chelate the choride anions through two N–H hydrogen bonds.

Copper(II) and nickel(II) complexes with a linear pentadentate ligand. The x-ray crystal structure of [CuL][CuCl4] (L = 1,9-bis-(2-pyridyl)-2,5,8-triazanonane)

Abstract Reactions between CuII and NiII salts and the ligand 1,9-bis-(2-pyridyl)-2,5,8-triazanonane at different stoichiometric relations produced two different complexes in the case of CuII and only one with NiII. The spectral properties of these complexes are discussed and the X-ray crystal structure of one of the CuII products is described. The compound consists of a CuII pentacoordinated complex cation (all the donor atoms in L are coordinated) and a tetrahedral [CuCl4]2− group. The coordination geometry of the cation can be described as a distorted square-based pyramid.

The reactivity of [Os3(CO)10(C2Ph2)] towards phenyl mercury halides

Abstract The reaction of Os3(CO)10(C2Ph2) with PhHgCl in benzene yields [Os3(CO)9 (μ3-C2Ph2)(μ2-Cl)(HgCl)] 2. The complex has been characterized by the usual spectroscopic methods and by an X-ray crystal, structure determination. The compound crystallizes in the triclinic space group P 1 , cell dimensions a = 9.727(3), b = 12.590(4), c = 14.863(7) A, α = 96.75(3), β = 109.02(3), γ = 99.58(2)°, V = 1667.8(8) A3, Z = 1. The three osmium atoms form a bent arrangement with the diphenyl acetylene and a chloride ion bridging the non-bonded (Os—Os distance of 3.768 A) osmium-osmium edge, a mercury atom bridges a metal-metal bond and is also bound, in an unsymmetrical fashion to two chlorine atoms which act as bridges to an identical triosmium-mercury unit. A toluene molecule is also present in the asymmetric unit.