The Chiral 1:2 Adduct (S)S(S)C(-)589-Ethyl 2-Phenylbutyl Sulphide-Mercury (II) Chloride:(-)589[(S)S(S)C-Et(2-PhBu)S.(HgCl2)2]. Stereoselective Synthesis, Asymmetric Oxidation, Crystal and Molecular Structure and Circular Dichroism Spectra.

Optically active (-)589ethyl (S)-2-phenylbutyl thioether, (-)(S)C-Et(PhBu)S (I), and its new diastereoisomeric mercury (II) chloride adduct, 1:2, (-)[(S)S(S)C-Et(PhBu)S.(HgCl2)2]2, (II) were stereoselectively synthesized; the absorbance (UV) and circular dichroism (CD) spectra were measured and the crystal and molecular structure of complex (II) was determined by single-crystal X-ray diffraction. Two different Hg centres are present whose coordination environments are built by two short bonds to chloride ligands in one case, and to one chloride and one sulphur in the other one. These originate digonal units. Electroneutrality is achieved by a further chlorine, which can be considered prevalently ionic and bonded to the two Hg centres, forming square bridging systems nearly perpendicular to the digonal molecules. The coordination polyhedra can be interpreted as 2 + 4 tetragonally-compressed octahedra with the four longer contacts lying in the equatorial plane. IR spectroscopic data are consistent with the presence of one bent and one linear Cl-Hg-Cl moiety. The absolute configurations at both stereogenic centres of the formed diastereoisomeric complex (II) are (S). The (S)S absolute configuration at the stereogenic sulphur atom bonded to the mercury(II) atom in complex (II) has been related with the negative Cotton effect assigned in its circular dichroism (CD) spectrum to a charge-transfer transition at ca. 230 nm. The stereoselective oxidation of (I) and (II) with hydrogen peroxide, induced by the stereogenic carbon atom (S)C of the enantiopure sulphide, gave (-)598ethyl (S)C-2-phenylbutyl(S)S-sulphoxide, (-)598[(S)S(S)C-Et(PhBu)SO], (III), having 18.1% de. Oxidations carried out in the presence of a 200 molar excess of mercury(II) chloride gave (-)598ethyl (S)C-2-phenylbutyl(R)S-sulphoxide, (-) 598[(R)S(S)C-Et(PhBu)SO], (IV) with 31% de, showing the cooperative influence of mercury(II) chloride on the selectivity of the oxidation reaction.

Synthesis, structure and characterization of novel Cd(II) and Zn(II) complexes with the condensation product of 2-formylpyridine and selenosemicarbazide Antiproliferative activity of the synthesized complexes and related selenosemicarbazone complexes.

Two novel Cd(II) and Zn(II) complexes with the condensation product of 2-formylpyridine and selenosemicarbazide were synthesized. The structure of Cd(II) complex was determined by X-ray crystallography. The ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms and the selenium donor. The cadmium ion completes its five-coordination by two chloride ligands, forming a square-pyramidal geometry. The structure of Zn(II) complex was established by analysis of spectroscopic data, which indicated coordination of the ligand as a bidentate via the selenium and the azomethine nitrogen atoms. The cytotoxic activity of the newly synthesized complexes, as well as if five structurally related complexes and the ligand evaluated against eight tumor cell lines. The new Cd(II) complex showed the highest activity similar to cisplatin with IC50 less than 10muM for all cell lines. Cell cycle distribution and apoptosis study showed that Cd(II) complex and cisplatin might have some similarity in anticancer activity, which was not the case for cisplatin and other studied complexes. Effects of the complexes on matrix metalloproteinases (MMPs) MMP-9 and MMP-2 was also studied. Cd(II) and Zn(II) complexes and cisplatin increased MMP-2 activity in supernatants of tested cells, while Ni(II) complex with the same ligand decreased the activity, implying a possible activity in preventing tumor invasion and metastasis processes.

Reactions of manganese and rhenium complexes with organic azides: preparation of tetraazabutadiene derivatives.

Azide complexes [M(RN(3))(CO)(3)P(2)]BPh(4)[M = Mn, Re; R = C(6)H(5)CH(2), 4-CH(3)C(6)H(4)CH(2), C(6)H(5), 4-CH(3)C(6)H(4), C(5)H(9); P = PPh(OEt)(2), PPh(2)(OEt)] were prepared by allowing tricarbonyl MH(CO)(3)P(2) hydride complexes to react first with Brønsted acid (HBF(4), CF(3)SO(3)H) and then with organic azide in the dark. In sunlight the reaction yielded tetraazabutadiene [M(eta(2)-1,4-R(2)N(4))(CO)(2)P(2)]BPh(4) complexes or, with benzyl azide, imine [M{eta(1)-NH[double bond, length as m-dash]C(H)Ar}(CO)(3)P(2)]BPh(4)(Ar = C(6)H(5), 4-CH(3)C(6)H(4)) derivatives. Tetraazabutadiene [M(eta(2)-1,4-R(2)N(4))(CO)(2)P(2)]BPh(4) complexes were also prepared by reacting dicarbonyl MH(CO)(2)P(3) species first with Brønsted acid and then with an excess of organic azide. Complexes were characterised spectroscopically (IR, (1)H, (31)P, (13)C, (15)N NMR data) and by the X-ray crystal structure determination of complex [Re{eta(2)-1,4-(C(6)H(5)CH(2))(2)N(4)}(CO)(2){PPh(OEt)(2)}(2)]BPh(4)(). Strong evidence for coordination of the organic azide was obtained from the (15)N NMR spectra of labelled [M(C(6)H(5)CH(2)(15)NN(15)N)(CO)(3)P(2)]BPh(4) derivatives.

Tautomerization of methyldiazene to formaldehyde-hydrazone in ruthenium and osmium complexes.

Mixed-ligand hydrazine complexes [M(CO)(RNHNH2)P4](BPh4)2 (1, 2) [M = Ru, Os; R = H, CH3, C6H5; P = P(OEt)3] with carbonyl and triethyl phosphite were prepared by allowing hydride [MH(CO)P4]BPh4 species to react first with HBF4.Et2O and then with hydrazines. Depending on the nature of the hydrazine ligand, the oxidation of [M(CO)(RNHNH2)P4](BPh4)2 derivatives with Pb(OAc)4 at -30 C gives acetate [M(kappa1-OCOCH3)(CO)P4]BPh4 (3a), phenyldiazene [M(CO)(C6H5N=NH)P4](BPh4)2 (3c, 4c), and methyldiazene [M(CO)(CH3N=NH)P4](BPh4)2 (3b, 4b) derivatives. Methyldiazene complexes 3b and 4b undergo base-catalyzed tautomerization of the CH3N=NH ligand to formaldehyde-hydrazone NH2N=CH2, giving the [M(CO)(NH2N=CH2)P4](BPh4)2 (5, 6) derivatives. Complexes 5 and 6 were characterized spectroscopically and by the X-ray crystal structure determination of the [Ru(CO)(NH2N=CH2)[P(OEt)3]4](BPh4)2 (5) derivative. Acetone-hydrazone [M(CO)[NH2N=C(CH3)2]P4](BPh4)2 (7, 8) complexes were also prepared by allowing hydrazine [M(CO)(NH2NH2)P4](BPh4)2 derivatives to react with acetone.

"Venetian blinds" mechanism of solvation/desolvation in palladium(II) wheel-and-axle organic-inorganic diols.

A family of organic-inorganic wheel-and-axle diols (Pd(LOH)(2)Cl(2), Pd(LOH)(2)(CH(3))Cl, Pd(LOH)(2)(CH(3)COO)(2), LOH = alpha-(4-pyridyl)benzhydrol) and several corresponding solvates are synthesized and characterized by single-crystal X-ray diffraction analysis. Their structures are compared to investigate the factors governing the modes of solid state association, the propensity to clathration, and the structural basis of guest inclusion. In all the complexes, the palladium coordination is a slightly distorted square. The LOH ligands coordinate Pd(2+) by means of the 4-pyridyl ring. In the chloride complexes solvation occurs with a 1:2 host/guest ratio by hydrogen bonding between the terminal -OH groups of the complex diol and one acceptor atom on the guest, and it is further assisted by guest stacking between host aryl rings. All solvates are organized in layers with practically invariant metrics, while the layers may be assembled in different arrangements. The structures of the nonsolvate compounds are related to the metrics of the solvate forms by rotation of the complex molecules within the layer plane. In all cases the nonsolvates are completely converted into the corresponding crystalline solvate forms by exposure to the vapor of the guest, and conversely they are quantitatively recovered from the solvate upon removal of the guest by mild conditions. On the basis of the structural data, it is proposed that the solvation/desolvation process proceeds by a concerted rotation of the complex molecules in the layer plane. The structural analysis of Pd(LOH)(2)(CH(3)COO)(2) and of its tetrahydrofuran monosolvate form suggests that the first step of the solid/gas solvation process may imply the clathration of 1 mol of guest between the aryl rings, which successively triggers the collective reorientation of the host molecules.

Preparation and reactivity of mixed-ligand ruthenium(II) hydride complexes with phosphites and polypyridyls.

Chloro complexes [RuCl(N-N)P3]BPh4 (1-3) [N-N = 2,2'-bipyridine, bpy; 1,10-phenanthroline, phen; 5,5'-dimethyl-2,2'-bipyridine, 5,5'-Me2bpy; P = P(OEt)3, PPh(OEt)2 and PPh2OEt] were prepared by allowing the [RuCl4(N-N)].H2O compounds to react with an excess of phosphite in ethanol. The bis(bipyridine) [RuCl(bpy)2[P(OEt)3]]BPh4 (7) complex was also prepared by reacting RuCl2(bpy)2.2H2O with phosphite and ethanol. Treatment of the chloro complexes 1-3 and 7 with NaBH4 yielded the hydride [RuH(N-N)P3]BPh4 (4-6) and [RuH(bpy)2P]BPh4 (8) derivatives, which were characterized spectroscopically and by the X-ray crystal structure determination of [RuH(bpy)[P(OEt)3]3]BPh4 (4a). Protonation reaction of the new hydrides with Brønsted acid was studied and led to dicationic [Ru(eta2-H2)(N-N)P3]2+ (9, 10) and [Ru(eta(2-H2)(bpy)2P]2+ (11) dihydrogen derivatives. The presence of the eta2-H2 ligand was indicated by a short T(1 min) value and by the measurements of the J(HD) in the [Ru](eta2-HD) isotopomers. From T(1 min) and J(HD) values the H-H distances of the dihydrogen complexes were also calculated. A series of ruthenium complexes, [RuL(N-N)P3](BPh4)2 and [RuL(bpy)2P](BPh4)2 (P = P(OEt)3; L = H2O, CO, 4-CH3C6H4NC, CH3CN, 4-CH3C6H4CN, PPh(OEt)2], was prepared by substituting the labile eta2-H2 ligand in the 9, 10, 11 derivatives. The reactions of the new hydrides 4-6 and 8 with both mono- and bis(aryldiazonium) cations were studied and led to aryldiazene [Ru(C6H5N=NH)(N-N)P3](BPh4)2 (19, 21), [[Ru(N-N)P3]2(mu-4,4'-NH=NC6H4-C6H4N=NH)](BPh4)4 (20), and [Ru(C6H5N=NH)(bpy)2P](BPh4)2 (22) derivatives. Also the heteroallenes CO2 and CS2 reacted with [RuH(bpy)2P]BPh4, yielding the formato [Ru[eta1-OC(H)=O](bpy)2P]BPh4 and dithioformato [Ru[eta1-SC(H)=S](bpy)2P]BPh4 derivatives.

Synthesis and spectroscopic and structural characterization of two novel photoactivatable Ca2+ compounds.

Two novel photoactivatable Ca(2+) compounds were synthesized to achieve a fast concentration jump of calcium ions in solution; this is of paramount importance for investigating the physiological cellular response. The light-sensitive ligands 4-(2-nitrophenyl)-3,6-dioxaoctane dioic acid (H2L1) and 4-(4,5-dimethoxy-2-nitrophenyl)-3,6-dioxaoctane dioic acid (H2L2) were generated by multistep syntheses, and the corresponding calcium complexes, Ca1 and Ca2, were isolated and characterized. The solution equilibria of H2L1 and H2L2 with Ca2+ were investigated; for both ligands, the formation of a 1:2 Ca2+/ligand species is detected and the complete characterization is presented. The crystal structures of Ca1 and Ca2 were determined. In Ca1 the solid state assembly is attained by a polymeric association of [(CaL1(H2O))2(mu-OH2)] dimeric units. Each calcium ion coordinates four oxygen atoms of one ligand (two ethereal, one carboxylic, and one bridging carboxylic oxygen atom), one water molecule, one bridging water molecule, and a carboxylate group of the other ligand within the dimer. The octacoordination of the metal is completed by an interaction with the adjacent dimeric unit. The crystal structure of the complex Ca2 does not show a polymeric nature, but it is a centrosymmetric dimer. The coordination number of the metal ion is still 8:4 oxygen atoms of the ligand; 3 water molecules; 1 bridging carboxylate group. A preliminary study of the photochemical features of the complexes Ca1 and Ca2 is reported: photoexcitation by a nanosecond pulsed UV laser induces the cleavage of the ligand. This drastically reduces the affinity of the ligand toward Ca2+, which is then released in solution.

Coordination of cyclo-octasulfur and cyclo-heptaselenium to dinuclear rhenium(I) systems.

By substitution reactions of the coordinated THF ligands of Re(2)(mu-X)(2)(CO)(6)(THF)(2) by elemental chalcogens (S(8) and red selenium), the complexes Re(2)(mu-X)(2)(CO)(6)(S(8)) (X = Br, 1; I, 2), and Re(2)(mu-X)(2)(CO)(6)(Se(7)), (X = I, 3; Br, 4) have been prepared. Binuclear compound 3 was crystallographically established to be a coordination compound of cyclo-heptaselenium, two adjacent selenium atoms of the Se(7) ligand [Se-Se distance, 2.558(3) A] being bonded to rhenium(I), at an average Re-Se distance of 2.586(3) A, and the nonbonding Re.Re distance being 4.077(3) A. Spectroscopic evidence of the existence of these chalcogen complexes in solution is reported. The Re(2)(mu-X)(2)(CO)(6)(S(8)) complexes undergo S(8) displacement by THF, while the coordinated Se(7) moiety is less readily displaced from 3.

Efficient and general synthesis of 5-(alkoxycarbonyl)methylene-3-oxazolines by palladium-catalyzed oxidative carbonylation of prop-2-ynylamides.

A variety of prop-2-ynylamides have been carbonylated under oxidative conditions to give oxazolines, oxazolines with chelating groups, and bisoxazolines bearing an (alkoxycarbonyl)methylene chain at the 5 position in good yields. The cyclization-alkoxycarbonylation process was carried out in alcoholic media at 50-70 degrees C and under 24 bar pressure of 3:1 carbon monoxide/air in the presence of catalytic amounts of 10% Pd/C or PdI2 in conjunction with KI. Cyclization occurred by anti attack of an oxygen function on the palladium-coordinated triple bond, followed by stereospecific alkoxycarbonylation, strictly resulting in E-stereochemistry. The structures of representative oxazolines and bisoxazolines have been determined by X-ray diffraction analysis.

Mono- and Bis(hydrazine) Complexes of Osmium(II): Synthesis, Reactions, and X-ray Crystal Structure of the [Os(NH(2)NH(2))(2){P(OEt)(3)}(4)](BPh(4))(2) Derivative.

Reaction of OsH(2)P(4) [P = P(OEt)(3), PPh(OEt)(2), PPh(2)OEt] with methyl triflate followed by the treatment with hydrazines gave the [OsH(RNHNH(2))P(4)]BPh(4) (1-3) (R = H, CH(3), C(6)H(5), 4-NO(2)C(6)H(4)) derivatives. Instead, the reaction of OsH(2)P(4) first with methyl triflate, then with triflic acid, and finally with an excess of the appropriate hydrazine afforded the bis(hydrazine) [Os(RNHNH(2))(2)P(4)](BPh(4))(2) (4, 5) (R = H, CH(3), C(6)H(5)) complexes. Also the [Os(NH(2)NH(2)){P(OEt)(3)}(5)](BPh(4))(2) (7) derivative was prepared. All the hydrazine complexes were fully characterized by IR and (1)H and (31)P NMR spectra, and a single-crystal X-ray structure determination of the complex [Os(NH(2)NH(2))(2){P(OEt)(3)}(4)](BPh(4))(2).C(2)H(5)OH (4a) is reported. The compound crystallizes in the space group P2(1)/c with a = 20.550(4) Å, b = 19.663(4) Å, c = 20.843(4) Å, beta = 99.84(9) degrees, and Z = 4. The coordination around the osmium atom is octahedral and the orientation of the ligands in the [Os(NH(2)NH(2))(2){P(OEt)(3)}(4)](2+) cation is determined by several strong hydrogen bonds involving hydrazine nitrogen and phosphite oxygen atoms. Amidrazone complexes [Os{eta(2)-NH=C(R1)N(R)NH(2)}{P(OEt)(3)}(4)](BPh(4))(2) (8, 9) (R = H, CH(3); R1 = CH(3), 4-CH(3)C(6)H(4)) were prepared by allowing nitrile complexes [Os(R1CN)(2)P(4)](BPh(4))(2) to react with hydrazine NH(2)NH(2) or methylhydrazine CH(3)NHNH(2). Reaction of complexes containing substituted hydrazine ligands of the type [OsH(RNHNH(2))P(4)]BPh(4) and [Os(RNHNH(2))(2)P(4)](BPh(4))(2) [P = P(OEt)(3); R = CH(3), C(6)H(5)] with Pb(OAc)(4) at -30 degrees C results in the selective oxidation of the hydrazine affording the corresponding diazene [OsH(RN=NH)P(4)]BPh(4) (10) and [Os(RN=NH)(2)P(4)](BPh(4))(2) (11) derivatives. The first bis(methyldiazene) complex [Os(CH(3)N=NH)(2){P(OEt)(3)}(4)](BPh(4))(2) (11b) was thus prepared.

Reactivity of Hydrides FeH(2)(CO)(2)P(2) (P = Phosphites) with Aryldiazonium Cations: Preparation, Characterization, X-ray Crystal Structure, and Electrochemical Studies of Mono- and Binuclear Aryldiazenido Complexes.

Mono- and binuclear aryldiazenido complexes [Fe(ArN(2))(CO)(2)P(2)]BPh(4) (1-4) and [{Fe(CO)(2)P(2)}(2)(&mgr;-N(2)Ar-ArN(2))](BPh(4))(2) (5-8) [P = P(OEt)(3), PPh(OEt)(2), PPh(2)OEt, P(OPh)(3); Ar = C(6)H(5), 2-CH(3)C(6)H(4), 4-CH(3)C(6)H(4); Ar-Ar = 4,4'-C(6)H(4)-C(6)H(4), 4,4'-(2-CH(3))C(6)H(3)-C(6)H(3)(2-CH(3)), 4,4'-C(6)H(4)-CH(2)-C(6)H(4)] were prepared by allowing hydride species FeH(2)(CO)(2)P(2) to react with an excess of mono- (ArN(2))(BF(4)) or bis-aryldiazonium (N(2)Ar-ArN(2))(BF(4))(2) salts, respectively, at low temperature. A reaction path involving a hydride-aryldiazene intermediate [FeH(ArN=NH)(CO)(2)P(2)](+), which, through the loss of H(2), affords the final aryldiazenido complexes 1-8, is proposed. The compounds were characterized by (1)H and (31)P{(1)H} NMR spectroscopy (including (15)N isotopic substitution) and X-ray crystal structure determination. The complex [Fe(CO)(2){P(OEt)(3)}(2){&mgr;-4,4'-N(2)(2-CH(3))C(6)H(3)-C(6)H(3)(2-CH(3))N(2)}](BPh(4))(2) (5b) crystallizes in the space group P&onemacr; with a = 15.008(4) Å, b = 17.094(5) Å, c = 10.553(3) Å, alpha = 99.56(1) degrees, beta = 102.80(1) degrees, gamma = 65.30(1) degrees, and Z = 1. The structure is centrosymmetric and consists of binuclear cations with the two iron atoms in a quite regular trigonal bipyramidal environment, with the two CO in the equatorial and the two phosphites in the apical position, respectively. Aryldiazenido complexes 1-8 react with strong acids HX (X = Cl, CF(3)SO(3), CF(3)CO(2)) to give the corresponding aryldiazene derivatives, according to the equilibrium [Fe(ArN(2))(CO)(2)P(2)](+) + HX right harpoon over left harpoon [FeX(ArN=NH)(CO)(2)P(2)](+). Electrochemical studies of both mono- (1-4) and binuclear (5-8) compounds were undertaken, and a mechanism for oxidation and reduction processes is proposed.

Aryldiazene, Aryldiazenido, and Hydrazine Complexes of Manganese. Preparation, Characterization, and X-ray Crystal Structures of [Mn(CO)(3)(4-CH(3)C(6)H(4)N=NH){PPh(OEt)(2)}(2)]BF(4) and [Mn(CO)(3)(NH(2)NH(2)){PPh(OEt)(2)}(2)]BPh(4) Derivatives.

Aryldiazene complexes [Mn(CO)(3)(ArN=NH)P(2)]BF(4) (1, 2) and [{Mn(CO)(3)P(2)}(2)(&mgr;-HN=NArArN=NH)](BF(4))(2) (3, 4) [P = PPh(OEt)(2), PPh(2)OEt; Ar = C(6)H(5), 2-CH(3)C(6)H(4), 4-CH(3)C(6)H(4), 4-CH(3)OC(6)H(4); ArAr = 4,4'-C(6)H(4)C(6)H(4), 4,4'-(2-CH(3))C(6)H(3)C(6)H(3)(2-CH(3)), 4,4'-C(6)H(4)CH(2)C(6)H(4)] were prepared by reacting hydride species MnH(CO)(3)P(2) with the appropriate aryldiazonium cations in CH(2)Cl(2) or acetone solutions at -80 degrees C. The compounds were characterized by IR, (1)H and (31)P NMR spectra (with (15)N isotopic substitution), and a single-crystal X-ray structure determination. The complex [Mn(CO)(3)(4-CH(3)C(6)H(4)N=NH){PPh(OEt)(2)}(2)]BF(4) (1c) crystallizes in the space group C2/c with a = 31.857(5) Å, b = 11.119(2) Å, c = 22.414(3) Å, beta = 97.82(1) degrees, and Z = 8. Treatment of aryldiazene compounds 1-4 with NEt(3) gave the pentacoordinate aryldiazenido [Mn(CO)(2)(ArN(2))P(2)] (5, 6) and [{Mn(CO)(2)P(2)}(2)(&mgr;-N(2)ArArN(2))] (7, 8) [P = PPh(OEt)(2), PPh(2)OEt; Ar = C(6)H(5), 4-CH(3)C(6)H(4); ArAr = 4,4'-C(6)H(4)C(6)H(4), 4,4'-(2-CH(3))C(6)H(3)C(6)H(3)(2-CH(3))] derivatives. Protonation reactions of these aryldiazenido complexes 5-8 with HCl afforded the aryldiazene [MnCl(CO)(2)(ArN=NH)P(2)] (9) and [{MnCl(CO)(2)P(2)}(2)(&mgr;-HN=NArArN=NH)] (10) derivatives. Hydrazine complexes [Mn(CO)(3)(RNHNH(2))P(2)]BPh(4) (11, 12) [P = PPh(OEt)(2), PPh(2)OEt; R = H, CH(3), C(6)H(5), 4-NO(2)C(6)H(4)] were prepared by allowing hydride species MnH(CO)(3)P(2) to react first with triflic acid and then with the appropriate hydrazine. Their characterization by IR, (1)H and (31)P NMR spectra, and an X-ray crystal structure determination is reported. The compound [Mn(CO)(3)(NH(2)NH(2)){PPh(OEt)(2)}(2)]BPh(4) (11a) crystallizes in the space group P&onemacr; with a = 13.772(3) Å, b = 14.951(4) Å, c = 13.319(3) Å, alpha = 104.47(1) degrees, beta = 100.32(1) degrees, gamma = 111.08(1) degrees, and Z = 2. Oxidation reactions of hydrazine compounds 11 and 12 with Pb(OAc)(4) at -40 degrees C gave stable aryldiazene [Mn(CO)(3)(RN=NH)P(2)]BPh(4) and thermally unstable (upon reaching -40 degrees C) diazene [Mn(CO)(3)(HN=NH)P(2)]BPh(4) derivatives.