Coordination compounds of N,N′-olefin functionalized imidazolin-2-ylidenes

N-Heterocyclic carbene ligands (NHC) were metalated with Pd(OAc)₂ or [Ni(CH₃CN)₆](BF₄)₂ by in situ deprotonation of imidazolium salts to give the N-olefin functionalized biscarbene complexes [MX₂(NHC)₂] 3-7 (3: M = Pd, X = Br, NHC = 1,3-di(3-butenyl)imidazolin-2-ylidene; 4: M = Pd, X = Br, NHC = 1,3-di(4-pentenyl)imidazolin-2-ylidene; 5: M = Pd, X = I, NHC = 1,3-diallylimidazolin-2-ylidene; 6: M = Ni, X = I, NHC = 1,3-diallylimidazolin-2-ylidene; 7: M = Ni, X = I, NHC = 1-methyl-3-allylimidazolin-2-ylidene). Molecular structure determinations for 4-7 revealed that square-planar complexes with cis (5) or trans (4, 6, 7) coordination geometry at the metal center had been obtained. Reaction of nickelocene with imidazolium bromides afforded the η⁵-cyclopentadienyl (η⁵-Cp) monocarbene nickel complexes [NiBr(η⁵-Cp)(NHC)] 8 and 9 (8: NHC = 1-methyl-3-allylimidazolin-2-ylidene; 9: NHC = 1,3-diallylimidazolin-2-ylidene). The bromine abstraction in complexes 8 and 9 with silver tetrafluoroborate gave complexes [NiBr(η⁵-Cp)(η³-NHC)] 10 and 11. The X-ray structure analysis of 10 and 11 showed a trigonal-pyramidal coordination geometry at the nickel(II) center and coordination of one N-allyl substituent.     

Photophysical properties and computational investigations of tricarbonylrhenium(I)[2-(4-methylpyridin-2-yl)benzo[d]-X-azole]L and tricarbonylrhenium(I)[2-(benzo[d]-X-azol-2-yl)-4-methylquinoline]L derivatives (X = N-CH3, O, or S; L = Cl, pyridine)

We report a combined experimental and computational study of new rhenium tricarbonyl complexes based on the bidentate heterocyclic N-N ligands 2-(4-methylpyridin-2-yl)benzo[d]-X-azole (X = N-CH₃, O, or S) and 2-(benzo[d]-X-azol-2-yl)-4-methylquinoline (X = N-CH₃, O, or S). Two sets of complexes are reported. Chloro complexes, described by the general formula Re(CO)₃[2-(4-methylpyridin-2-yl)benzo[d]-X-azole]Cl (X = N-CH₃, 1; X = O, 2; X = S, 3) and Re(CO)₃[2-(benzo[d]-X-azol-2-yl)-4-methylquinoline]Cl (X = N-CH₃, 4; X = O, 5; X = S, 6) were synthesized heating at reflux Re(CO)₅Cl with the appropriate N-N ligand in toluene. The corresponding pyridine set {Re(CO)₃[2-(4-methylpyridin-2-yl)benzo-X-azole]py}PF₆ (X = N-CH₃, 7; X = O, 8; X = S, 9) and {Re(CO)₃[2-(benzo[d]-X-azol-2-yl)-4-methylquinoline]py}PF₆ (X = N-CH₃, 10; X = O, 11; X = S, 12) was synthesized by halide abstraction with silver nitrate of 1-6 followed by heating in pyridine and isolated as their hexafluorophosphate salts. All complexes have been fully characterized by IR, NMR, electrochemical techniques and luminescence. The crystal structures of 1 and 7 were obtained by X-ray diffraction. DFT and time-dependent (TD) DFT calculations were carried out for investigating the effect of the organic ligand on the optical properties and electronic structure of the reported complexes.     

Diphenylphosphino(phenyl pyridin-2-yl methylene)amine palladium(II) complexes: Chemoselective alkene hydrocarboxylation initiators

The heteroditopic, P-N-chelating ligand diphenylphosphino(phenyl pyridin-2-yl methylene)amine (1) has been synthesised via a simple ‘one-pot’ procedure and its donor characteristics assessed. The neutral [MX(Y)(1-κ²-P-N)] (3, M = Rh, X = Cl, Y = CO; 4, M = Pd, X = Y = Cl; 5, M = Pd, X = Cl, Y = Me; 6, M = Pt, X = Y = Cl; 7, M = Pt, X = Cl, Y = Me; 8, M = Pt, X = Y = Me) and cationic [Pd(Me)(MeCN)(1-κ²-P-N)][Z] (9, Z = B{3,5-(CF₃)₂-C₆H₃}4; 10, Z = PF₆) complexes of 1 have been prepared and characterised. The solid-state structures of complexes 3, 4, 6 and 7 have been established by X-ray crystallography. Reactions of [PdCl(Me)(1-κ²-P-N)] towards CO and ^tBuNC have been investigated, affording the corresponding η¹-acyl (12) and -iminoacyl (14) complexes, respectively. Similar insertion chemistry is observed for the cationic derivative 9. Treatment of the acyl complex 12 with ethene at elevated pressure establishes an equilibrium between the starting material and the product resulting from insertion, 13. Under catalytic conditions, combination of palladium(II) with 1 in MeOH affords a selective initiator for the formation of 4-oxo-hexanoic acid methyl ester (15) from CO/ethene (38 bar, 90 °C).     

The chemistry of niobium and tantalum halides,MX5, with haloacetic acids and their related anhydrides: Anhydride C–H bond activation promoted by MF5

Niobium and tantalum pentahalides, MX₅ (1), react with acetic acid and halo-substituted acetic acids, in 1:1 ratio, to give the dinuclear complexes [MX₄(μ-OOCMe)]₂ [M = Nb, X = Cl, 2a; M = Ta, X = Cl, 2b; Br, 2c] and [MCl₄(μ-OOCR)]₂ [M = Nb, R = CH₂Cl, 4a; CHCl₂, 4c; CCl₃, 4e; CF₃, 4g; CHBr₂, 4i; CH₂I, 4j; M = Ta, R = CH₂Cl, 4b; CHCl₂, 4d; CCl₃, 4f; CF₃, 4h]. The solid state structures of 2b and 4e have been ascertained by X-ray diffraction studies. The reactions of 1 with acetic anhydride and halo-substituted acetic anhydrides result in C–O bond activation and afford 2 and 4, respectively, with concomitant formation of acetyl halides. Moreover, the complexes MCl₅[OC(Cl)Me] [M = Nb, 3a; M = Ta, 3b] have been detected in significant amounts within the mixtures of the reactions of MCl₅ with acetic anhydride. TaI₅ is unreactive, at room temperature, towards both MeCOOH and (MeCO)₂O. MF₅ react with RCOOH (R = Me, CH₂Cl) in 1:1 molar ratio, to afford the ionic compounds [MF₄(RCOOH)₂][MF₆], 5a–d, in high yields. The additions of (RCO)₂O (R = Me, CH₂Cl) to MF₅ give 5, suggesting that anhydride C–H and C–O bonds activation is operative during the course of these reactions.     

Rhenium(I) tricarbonyl complexes with bispyridine ligands attached to sulfur-rich core: Syntheses, structures and properties

Rhenium(I) tricarbonyl complexes with bispyridine ligands bearing sulfur-rich pendant, Re(CO)₃(Medpydt)X (Medpydt = dimethyl 2-(di(2-pyridyl)methylene)-1,3-dithiole-4,5-dicarboxylate; X = Cl, 1; X = Br, 2) and Re(CO)₃(MebpyTTF)X (MebpyTTF = 4,5-bis(methyloxycabonyl)-4′,5′-(4′-methyl-2,2′-dipyrid-4-ylethylenedithio)-tetrathiafulvalene; X = Cl, 5; X = Br, 6), were prepared from the reactions between Re(CO)₅X (X = Cl, Br) and Medpydt or MebpyTTF, respectively. Hydrolysis of the above complexes afforded the analogues with carboxylate derivatives, Re(CO)₃(H₂dpydt)X (X = Cl, 3; X = Br, 4) and Re(CO)₃(H₂bpyTTF)X (X = Cl, 7; X = Br, 8). The crystal structures for complexes 1 · 2H₂O, 5 and 6 were determined using X-ray single crystal diffraction. UV-Vis absorption spectra of the rhenium complexes show the intraligand and MLCT transitions. Electrochemical behaviors of all new compounds were studied with cyclic voltammetry. Upon irradiation, complexes 3-6 exhibit blue to red emissions in fluid solutions at the room temperature. The performance of complexes 3, 4, 7 and 8 as photosensitizers for anatase TiO₂ solar cells was preliminarily investigated as well.     

Synthesis, characterization, and norbornene polymerization of η-benzylnickel(II) complexes of N-heterocyclic carbenes

Neutral η¹-benzylnickel carbene complexes, [Ni(η¹-CH₂C₆H₅)(IiPr)(PMe₃)(Cl)] (3) (IiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) and [Ni(η¹-CH₂C₆H₅)(SIiPr)(PMe₃)(Cl)] (4) (SIiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidene), were prepared by the reaction between [Ni(η³-CH₂C₆H₅)(PMe₃)(Cl)] and an equivalent amount of the corresponding free N-heterocyclic carbene. The preparation of η³-benzylnickel carbene complexes, [Ni(η³-CH₂C₆H₅)(IiPr)(Cl)] (5) and [Ni(η³-CH₂C₆H₅)(SIiPr)(Cl)] (6) were carried out by the abstraction of PMe₃ from 3 and 4 by the treatment of B(C₆F₅)₃. The treatment of AgX on 5 and 6 produced the anion-exchanged complexes, [Ni(η³-CH₂C₆H₅)(NHC)(X)] (7, NHC = IiPr, X = O₂CCF₃; 8, NHC = IiPr, X = O₃SCF₃; 9, NHC = SIiPr, X = O₂CCF₃; 10, NHC = SIiPr, X = O₃SCF₃). The solid state structures of 3 and 10 were determined by X-ray crystallography. The η³-benzyl complexes of IiPr (5, 7, and 8) alone, in the absence of any activators such as borate and MAO, showed good catalytic activity towards the vinyl-type norbornene polymerization. The catalyst was thermally robust and the activity increases as the temperature rises to 130 °C.     

Titanocene-based group-11 metal ions; solid-state structure of {[(η-C5H4SiMe3)2Ti(CCPh)2]2Ag}NO3

The reaction of [Ti](CCR)₂ {[Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; 1a, R = Fc, Fc = (η⁵-C₅H₄)Fe(η⁵-C₅H₅); 1b, R = Ph} with MX {2a, MX = [Cu(NCCH₃)₄]BF₄; M = Ag; 2b, X = ClO₄; 2c, X = NO₃} in a 2:1 molar ratio produces the trinuclear heterobimetallic (Ti₂M) or heptanuclear heterotrimetallic (Ti₂MFe₄) complexes [{[Ti](μ-σ,π-CCR)₂}₂M]X (R = Fc: 3a, M = Cu, X = BF₄; 3b, M = Ag, X = ClO₄. R = Ph: 3c, M = Cu, X = BF₄; 3d, M = Ag, X = ClO₄: 3e, M = Ag, X = NO₃) in high yield. Complexes 3c-3e are also accessible, when {[Ti](μ-σ,π-CCPh)₂}MX (M = Cu: 4a, X = FBF₃; M = Ag: 4b, X = OClO₃; 4c, X = ONO₂) is reacted with one equivalent of 1b. Transferring this reaction scheme to [Ti](CCSiMe₃)₂ (1c) only the formation of the heterobimetallic tweezer complex {[Ti](μ-σ,π-CCSiMe₃)₂}MX {4d, MX = [Cu(NCCH₃)]BF₄; 4e, MX = AgOClO₃} is observed which is attributed to the bulkiness of the acetylide-bound Me₃Si group. The solid-state structure of 3e is reported. In 3e, two [Ti](CCPh)₂ tweezer moieties are chelate-bound by their carbon-carbon triple bonds to a silver(I) ion, resulting in a pseudo-tetrahedral environment at the group-11 metal. is acting as counter-ion to cationic [{[Ti](CCPh)₂}₂Ag]⁺.Additionally, the result of cyclic voltammetric studies on [{[Ti](μ-σ,π-CCPh)₂}₂Cu]BF₄ (3c) is reported.     

The preparation, properties and X-ray structures of gold(I) trithiophosphite complexes

The first gold(I) trithiophosphite complexes were synthesised and fully characterised. Reaction of (tht)AuX (X = Cl, C₆F₅; tht = tetrahydrothiophene) with trithiophosphites (RS)₃P (R = Me, Ph) and the bicyclic [(SCH₂CH₂S)PSCH₂]₂ (²L) afforded the corresponding molecular complexes (RS)₃PAuX [R = Me, X = Cl (1); R = Me, X = C₆F₅ (2); R = Ph, X = Cl (3); R = Ph, X = C₆F₅ (4)], and ²L(AuX)₂ [X = Cl (5), X = C₆F₅ (6)]. Reacting (tht)AuCl consecutively with two mole equivalents of (MeS)₃P and then AgOTf, gave the ionic compound {[(MeS)₃P]₂Au}OTf (7). The compounds were characterised by multinuclear NMR spectroscopy, IR measurements and mass spectrometry, and the crystal and molecular structures of 1, 3, 6, two polymorphs of 2 as well as the known (MeO)₃PAuCl (8) were determined by X-ray diffraction. The halide complexes 1 and 8 are isostructural and exhibit infinite chains of “crossed-sword”-type aurophilic interactions with Au?Au contact distances of 3.2942(3) and 3.1635(4) Å, respectively. Complex 6 exhibits a long Au?Au contact of 3.4671(9) Å. Au?S interactions between 3.3455(7) and 3.520(2) Å are present in the structures of 1 and one polymorph of 2.     

New versatile organyltellurium(IV) halides: Synthesis and X-ray structural features of the telluronium tellurolate salts [PhTe(CH3)2]2[TeX6] (X = Cl, Br) and [Ph3Te][PhTeX4] (X = Cl, Br, I)

TeX₄ (X = Cl, Br) react in HCl/HBr with [Ph(CH₃)₂Te]X (X = Cl, Br) to give [PhTe(CH₃)₂]₂[TeCl₆] (1) and [PhTe(CH₃)₂]₂[TeBr₆] (2). The reaction of PhTeX₃ (X = Cl, Br, I) in cooled methanol with [(Ph)₃Te]X (X = Cl, Br, I) leads to [Ph₃Te][PhTeCl₄] (3), [Ph₃Te][PhTeBr₄] (4) and [Ph₃Te][PhTeI₄] (5). In the lattices of the telluronium tellurolate salts 1 and 2, octahedral TeCl₆ and TeBr₆ dianions are linked by telluronium cations through Te?Cl and Te?Br secondary bonds, attaining bidimensional (1) and three-dimensional (2) assemblies. The complexes 3, 4 and 5 show two kinds of Te?halogen secondary interactions: the anion-anion interactions, which form centrosymmetric dimers, and two identical sets of three telluronium-tellurolate interactions, which accomplish the centrosymmetric fundamental moiety of the supramolecular arrays of the three compounds, with the tellurium atoms attaining distorted octahedral geometries. Also phenyl C-H?halogen secondary interactions are structure forming forces in the crystalline structures of compounds 3, 4 and 5.     

Syntheses and characterization of [(η-C6Me6)Ru(μ-N3)(X)]2 (X = N3 and Cl) complexes and their reactions towards mono- and bidentate ligands

The reaction of the complex [{(η⁶-C₆Me₆)Ru(μ-Cl)Cl}₂] 1 with sodium azide ligand gave two new dimers of the composition [{(η⁶-C₆Me₆)Ru(μ-N₃)(N₃)}₂] 2 and [{(η⁶-C₆Me₆)Ru(μ-N₃)Cl}₂] 3, depending upon the reaction conditions. Complex 3 with excess of sodium azide in ethanol yielded complex 2. These complexes undergo substitution reactions with monodentate ligands to yield monomeric complexes of the type [(η⁶-C₆Me₆)Ru(X)(N₃)(L)] {X = N₃, Cl, L = PPh₃ (4a, 9a); PMe₂Ph (4b, 9b); AsPh₃ (4c, 9c); X = N₃, L = pyrazole (Hpz) (5a); 3-methylpyrazole (3-Hmpz) (5b) and 3,5-dimethyl-pyrazole (3,5-Hdmpz) (5c)}. Complexes 2 and 3 also react with bidentate ligands to give bridging complexes of the type [{(η⁶-C₆Me₆)Ru(N₃)(X)]₂(μ-L)} {X = N₃, Cl, L = 1,2-bis(diphenylphosphino)methane (dppm) (6, 10); 1,2-bis(diphenylphosphino)ethane (dppe) (7, 11); 1,2-bis(diphenylphosphino)propane (dppp) (8, 12); X = Cl, L = 4,4-bipyridine (4,4′-bipy) (13)}. These complexes were characterized by FT-IR and FT-NMR spectroscopy as well as by analytical data.The molecular structures of the representative complexes [{(η⁶-C₆Me₆)Ru(μ-N₃)(N₃)}₂] 2, [{(η⁶-C₆Me₆)Ru(μ-N₃)Cl}₂] 3,[(η⁶-C₆Me₆)Ru(N₃)₂(PPh₃)] 4a and [{(η⁶-C₆Me₆)Ru(N₃)₂}₂ (μ-dppm)] 6 were established by single crystal X-ray diffraction studies.     

The cyclopalladation reaction of 2-phenylaniline revisited

2-Phenylaniline reacted with Pd(OAc)₂ in toluene at room temperature for 24 h in a one-to-one molar ratio and with the system PdCl₂, NaCl and NaOAc in a 1 (2-phenylaniline):1 (PdCl₂):2 (NaCl):1 (NaOAc) molar ratio in methanol at room temperature for one week to give the dinuclear cyclopalladated compounds (μ-X)₂[Pd{κ²-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}]₂ [1a (X = OAc) and 1b (X = Cl)] in high yield. Moreover, the reaction between 2-phenylaniline and Pd(OAc)₂ in one-to-one molar ratio in acid acetic at 60 °C for 4 h, followed by a metathesis reaction with LiBr, allowed isolation of the dinuclear cyclopalladated compound (μ-Br)₂[Pd{κ²-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}]₂ (1c) in moderate yield. A parallel treatment, but using monodeuterated acetic acid (DOAc) as solvent in the cyclopalladation reaction, allowed isolation of a mixture of compounds 1c, 1c_d1 [Pd{κ²-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄](μ-Br)₂[Pd{κ²-N2′,C1-2-(2′-NH₂C₆H₄)-3-d-C₆H₃] and 1c_d2 (μ-Br)₂[Pd{κ²-N2′,C1-2-(2′-NH₂C₆H₄)-3-d-C₆H₃}]₂ in moderate yield and with a deuterium content of ca. 60%. 1a and 1b reacted with pyridine and PPh₃ affording the mononuclear cyclopalladated compounds [Pd{κ²-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}(X)(L)] [2a (X = OAc, L = py), 2b (X = Cl, L = py), 3a (X = OAc, L = PPh₃) and 3b (X = Cl, L = PPh₃)] in a yield from moderate to high. Furthermore, 1a reacted with Na(acac) · H₂O to give the mononuclear cyclopalladated compound 4 [Pd{κ²-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}(acac)] in moderate yield. ¹H NMR studies in CDCl₃ solution of 2a, 2b, 3a, 3b and 4 showed that 2a and 3a presented an intramolecular hydrogen bond between the acetato ligand and the amino group, and were involved in a dynamic equilibrium with water present in the CDCl₃ solvent; and that the enantiomeric molecules of 2b and 4 were in a fast exchange at room temperature, while they were in a slow exchange for 2a, 3a and 3b. The X-ray crystal structures of 3b and 4 were determined. 3b crystallized in the triclinic space group with a = 9.9170(10), b = 10.4750(10), c = 12.0890(10) Å, α = 98.610(10)°, β = 94.034(10)° and γ = 99.000(10)° and 4 in the monoclinic space group P2₁/a with a = 11.5900(10), b = 11.2730(10), c = 12.2150(10) Å, α = 90°, β = 107.6560(10)° and γ = 90°.     

New mercury(II) and cadmium(II) complexes with (p-methylbenzoyl)methylene triphenylphosphorane: Synthesis,spectroscopic and structural characterization

Reaction of Ph₃PCHCOC₆H₄Me (L), with HgX₂ and CdCl₂·H₂O in methanol with equimolar ratios give binuclear complexes of the type [MX(μ-X){CH(PPh₃)C(O)C₆H₄Me}]₂ (M = Hg; X = Cl (1), Br (2), I (3), M = Cd; Cl(4)). The bridge-splitting reaction of binuclear complexes [MX(μ-X){CH(PPh₃)C(O)C₆H₄Me}]₂ by dimethyl sulfoxide (DMSO) yields the mononuclear complexes [MX₂{CH(PPh₃)C(O)C₆H₄Me}(OSMe₂)] (M = Hg; X = Cl (5), Br (6), I (7), M = Cd; Cl (8)). The characterization of these complexes was carried out by elemental analysis and FT-IR, ¹H, ³¹P, and ¹³C NMR spectroscopies. C-coordination of ylide and O-coordination of DMSO are demonstrated by single-crystal X-ray analysis of mononuclear complex of [HgBr₂{CH(PPh₃)C(O)C₆H₄Me}(OSMe₂)] (6). Complex 6 is monomeric with tetrahedral geometry around the metal ion.     

Structural and spectral investigations on some new Ni(II) complexes of di-2-pyridyl ketone N(4)-phenylthiosemicarbazone

Ni(II) complexes (1–5) of di-2-pyridyl ketone N(4)-phenylthiosemicarbazone (HL) have been synthesized and spectrochemically characterized. Elemental analyses revealed a NiL₂ · 2H₂O stoichiometry for compound 1. However, the single crystals isolated revealed a composition NiL₂ · 0.5(H₂O)0.5(DMF). The compound crystallizes into a monoclinic lattice with the space group P2₁/n. Complexes 2, 3 and 4 are observed to show a 1:1:1 ratio of metal:thiosemicarbazone:gegenion, with the general formula NiLX · yH₂O [X = NCS, y = 2 for 2; X = Cl, y = 3 for 3 and X = N₃, y = 4.5 for 4]. Compound 5 is a dimer with a metal:thiosemicarbazone:gegenion ratio of 2:2:1, with the formula [Ni₂L₂(SO₄)] · 4H₂O.     

Novel hydridotris(pyrazolyl)borate ruthenium(II) complexes containing the water-soluble phosphane 1,3,5-triaza-7-phosphaadamantane: Synthesis and evaluation of DNA binding properties

A series of half-sandwich ruthenium(II) complexes containing κ³(N,N,N)-hydridotris(pyrazolyl)borate (κ³(N,N,N)-Tp) and the water-soluble phosphane 1,3,5-triaza-7-phosphaadamantane (PTA) [RuX{κ³(N,N,N)-Tp}(PPh₃)_2−n(PTA)_n] (n = 2, X = Cl (1), n = 1, X = Cl (2), I (3), NCS (4), H (5)) and [Ru{κ³(N,N,N)-Tp}(PPh₃)(PTA)L][PF₆] (L = NCMe (6), PTA (7)) have been synthesized. Complexes containing 1-methyl-3,5-diaza-1-azonia-7-phosphaadamantane(m-PTA) triflate [RuCl{κ³(N,N,N)-Tp}(m-PTA)₂][CF₃SO₃]₂ (8) and [RuX{κ³(N,N,N)-Tp}(PPh₃)(m-PTA)][CF₃SO₃] (X = Cl (9), H (10)) have been obtained by treatment, respectively, of complexes 1, 2 and 5 with methyl triflate. Single crystal X-ray diffraction analysis for complexes 1, 2 and 4 have been carried out. DNA binding properties by using a mobility shift assay and antimicrobial activity of selected complexes have been evaluated.     

Formation and crystal structures of [(alkoxy)bis(pyridin-2-yl)methanolato-N,O,N]tin(IV) complexes

Reactions of bis(pyridin-2-yl)ketone with tin tetrahalides, SnX₄ (X = Cl or Br), or organotin trichlorides, R^′SnCl₃ (R^′ = Ph, Bu or CH₂CH₂CO₂Me), in ROH (R = Me or Et) readily produces RObis(pyridin-2-yl)methanolato)tin complexes, [5: RO(py)₂C(OSnX₃)] (5: R,X = Me,Cl; Et,Cl; Et,Br) or [6: MeO(py)₂C(OSnCl₂R^′)] (R^′ = Ph, Bu, CH₂CH₂CO₂Me). In addition, halide exchange reaction between SnI₄ and (5: R,X = Me,Cl) occurred to give (5: R,X = Me,I). The crystal structures of six tin(IV) derivatives indicated, in all cases, a monoanionic tridentate ligand, [RO(py)₂C(O⁻)-N,O,N], arranged in a fac manner about a distorted octahedral tin atom. The Sn–O and Sn–N bonds lengths do not show much variation amongst the six complexes despite the differences in the other ligands at tin.     

The interplay of secondary Te?N, Te?O, Te?I and I?I interactions, Te?π contacts and π-stacking in the supramolecular structures of [{2-(4-nitrobenzylideneamino)-5-methyl}phenyl](4-methoxyphenyl)tellurium dihalides

The unsymmetrically substituted diorganotellurium dihalides [2-(4,4′-NO₂C₆H₄CHNC₆H₃Me]RTeX₂ (R = 4-MeOC₆H₄, X = Cl, 1a; Br, 1b; I, 1c; R = 4-MeC₆H₄; X = Cl, 2; R = C₆H₅, X = Cl, 3) were prepared in good yields and characterized by solution and solid-state ¹²⁵Te NMR spectroscopy, IR spectroscopy and X-ray crystallography. In the solid-state, molecular structures of 1a and 1c possess scarcely observed 1,4-type intramolecular Te?N secondary interaction. Crystal packing of these compounds show an unusually rich diversity of intermolecular secondary, Te?O, Te?I and I?I interactions, Te?π contacts as well as extensive π-stacking of the organic substituents.     

Synthesis, characterization, reactivity and computational studies of new rhenium(I) complexes with thiosemicarbazone ligands derived from 4-(methylthio)benzaldehyde

N-thioamide thiosemicarbazone derived from 4-(methylthio)benzaldehyde (R = H, HL¹; R = Me, HL² and R = Ph, HL³) have been prepared and their reaction with fac-[ReX(CO)₃(CH₃CN)₂] (X = Br, Cl) in methanol gave the adducts [ReX(CO)₃(HLⁿ)] (1a X = Cl, n = 1; 1a′ X = Br, n = 1; 1b X = Cl, n = 2; 1b′ X = Br, n = 2; 1c X = Cl, n = 3; 1c′ X = Br, n = 3) in good yield.All the compounds have been characterized by elemental analysis, mass spectrometry (ESI), IR and ¹H NMR spectroscopic methods. Moreover, the structures of HL², HL³, HL³·(CH₃)₂SO and 1b′·H₂O were also elucidated by X-ray diffraction. In 1b′, the rhenium atom is coordinated by the sulphur and the azomethine nitrogen atoms (κS,N³) forming a five-membered chelate ring, as well as three carbonyl and bromide ligands. The resulting coordination polyhedron can be described as a distorted octahedron.The structure of the dimers is based on rhenium(I) thiosemicarbazonates [Re₂(L¹)₂(CO)₆] (2a), [Re₂(L²)₂(CO)₆] (2b) and [Re₂(L³)₂(CO)₆] (2c) as determined by X-ray studies. Methods of synthesis were optimized to obtain amounts of these thiosemicarbazonate complexes. In these compounds the dimer structures are achieved by Re-S-Re bridges, where S is the thiolate sulphur from a κS,N³-bidentate thiosemicarbazonate ligand.Some single crystals isolated in the synthesis of 2b contain [Re(L⁴)(L²)(CO)₃] (3b) where L⁴ (=2-methylamine-5-(para-methylsulfanephenyl)-1,3,4-thiadiazole) is originated in a cyclization process of the thiosemicarbazone. Furthermore, the rhenium atom is coordinate by the sulphur and the thioamidic nitrogen of the thiosemicarbazonate (κS,N²) affording a four-membered chelate ring.     

Copper(I) complexes of a thioether-functionalized short-bite aminobis(phosphonite), [PhN{P(–OC10H6(μ-S)C10H6O–)}2]

Copper(I) complexes of short-bite aminobis(phosphonite), PhN{P(–OC₁₀H₆(μ-S)C₁₀H₆O–)}₂ (1) have been synthesized. Reactions of 1 with an excess of CuX (X = Cl, Br, and I) afforded the ligand-bridged binuclear complexes, [PhN(PR-κP)₂{Cu(μ-X)(MeCN)}₂] (2, X = Cl; 3, X = Br; 4, X = I; R = –OC₁₀H₆(μ-S)C₁₀H₆O–), whereas treatment with 0.5 equiv. of [Cu(MeCN)₄]PF₆ produces the mononuclear bischelated cationic complex, [{PhN(PR-κP)₂}₂Cu](PF₆) (5). Single crystal X-ray structures of complexes 3 and 4 are reported. Complex 3 shows strong π–π stacking interactions between the naphthyl moieties, whereas complex 4 shows ligand-supported Cu?Cu metallophilic interactions.     

Nucleophilic substitution reactions at the Si-Cl bonds of the dichloro(methyl)silyl ligand in five- and six-coordinate complexes of ruthenium(II) and osmium(II)

Treatment of either RuHCl(CO)(PPh₃)₃ or MPhCl(CO)(PPh₃)₂ with HSiMeCl₂ produces the five-coordinate dichloro(methyl)silyl complexes, M(SiMeCl₂)Cl(CO)(PPh₃)₂ (1a, M = Ru; 1b, M = Os). 1a and 1b react readily with hydroxide ions and with ethanol to give M(SiMe[OH]₂)Cl(CO)(PPh₃)₂ (2a, M = Ru; 2b, M = Os) and M(SiMe[OEt]₂)Cl(CO)(PPh₃)₂ (3a, M = Ru; 3b, M = Os), respectively. 3b adds CO to form the six-coordinate complex, Os(SiMe[OEt]₂)Cl(CO)₂(PPh₃)₂ (4b) and crystal structure determinations of 3b and 4b reveal very different Os-Si distances in the five-coordinate complex (2.3196(11) Å) and in the six-coordinate complex (2.4901(8) Å). Reaction between 1a and 1b and 8-aminoquinoline results in displacement of a triphenylphosphine ligand and formation of the six-coordinate chelate complexes M(SiMeCl₂)Cl(CO)(PPh₃)(κ²(N,N)-NC₉H₆NH₂-8) (5a, M = Ru; 5b, M = Os), respectively. Crystal structure determination of 5a reveals that the amino function of the chelating 8-aminoquinoline ligand is located adjacent to the reactive Si-Cl bonds of the dichloro(methyl)silyl ligand but no reaction between these functions is observed. However, 5a and 5b react readily with ethanol to give ultimately M(SiMe[OEt]₂)Cl(CO)(PPh₃)(κ²(N,N-NC₉H₆NH₂-8) (6a, M = Ru; 6b, M = Os). In the case of ruthenium only, the intermediate ethanolysis product Ru(SiMeCl[OEt])Cl(CO)(PPh₃)(κ²(N,N-NC₉H₆NH₂-8) (6c) was also isolated. The crystal structure of 6c was determined. Reaction between 1b and excess 2-aminopyridine results in condensation between the Si-Cl bonds and the N-H bonds with formation of a novel tridentate “NSiN” ligand in the complex Os(κ³(Si,N,N)-SiMe[NH(2-C₅H₄N)]₂)Cl(CO)(PPh₃) (7b). Crystal structure determination of 7b shows that the “NSiN” ligand coordinates to osmium with a “facial” arrangement and with chloride trans to the silyl ligand.