Synthesis and characterization of triphenylphosphine stabilized silver α,β-unsaturated carboxylate: Crystal structure of [Ag(O2CCHC(CH3)2)(PPh3)2]

A series of triphenylphosphine coordinated silver α,β-unsaturated carboxylates of type [Ag(O₂CR)(PPh₃)_n: n = 1, R = CH₃CHCH (2a), (CH₃)₂CCH (2b), CH₃CH₂CHCH (2c), CH₃CH₂CH₂CHCH (2d), PhCHCH (2e), CH₂CH (2f); n = 2, CH₃CHCH (3a), (CH₃)₂CCH (3b), CH₃CH₂CHCH (3c), CH₃CH₂CH₂CHCH (3d)] were prepared by reaction of relative silver carboxylates (1a-1f) with triphenylphosphine in chloroform. These complexes were obtained in high yields and characterized by elemental analysis, ¹H NMR, ¹³C NMR, ³¹P NMR and IR spectroscopy. Thermal stability of the complexes has been determined by TG analysis. The molecular structure of [Ag((O₂CCHC(CH₃)₂))(PPh₃)₂] (3b) shows that the senecioato ligand is chelated with silver atom and generate, a distorted tetrahedron.     

Modification of aminoallenylidene complexes of chromium via exchange of the C3-bound amino group

The aminoallenylidene(pentacarbonyl)chromium complexes [(CO)₅CrCCC(NR¹R²)Ph] (1a-c) react with dimethylamine by addition of the amine to the C1C2 bond of the allenylidene ligand to give alkenyl(amino)carbene complexes [(CO)₅CrC(NMe₂)CHC(NR¹R²)Ph] (2a-c) (R¹ = Me: R² = Me (a), Ph (b); R¹ = Et: R² = Ph (c)). In contrast, addition of a large excess (usually 20 equivalents) of ammonia or primary amines, H₂NR, to solutions of [(CO)₅CrCCC(NMe₂)Ph] (1a) affords the aminoallenylidene complexes [(CO)₅CrCCC(NHR)Ph] (1d-w) in which the dimethylamino group is replaced by NH₂ or NHR, respectively. In addition to simple amines such as methylamine, butylamine, and aniline, amines carrying a functional group (allylamine, propargylamine) and amino acid esters as well as amino terpenes and amino sugars can be used to displace the NMe₂ substituent. Usually the Z isomer (with respect to the partial C3-N double bond) is formed exclusively. Products derived from addition of H₂NR to the C1C2 bond of 1a are not observed. The amino group in 1d-w is rapidly deprotonated by excess of amine to form iminium alkynyl chromates [1d-w]⁻, thus protecting 1d-w from addition of free amine to either C3 or across the C1C2 bond. The iminium alkynyl chromates are readily reprotonated by acids or by chromatography on wet SiO₂ to reform 1d-w.     

A closer look at the phosphorus-phosphorus double bond lengths in meta-terphenyl substituted diphosphenes

The single crystal X-ray structure of DmpPPDmp (1, Dmp = 2,6-Mes₂C₆H₃), which was previously reported to have a relatively short PP bond distance of 1.985(2) Å at room temperature, has been reexamined at variable temperatures. Crystallographic analyses of 1 at 100 K allow for resolution of disorder of the two phosphorus atoms (which is unresolvable from room temperature diffraction data), and for determination of a more conventional PP bond length of 2.029(1) Å. Single crystals of the closely related diphosphene DxpPPDxp (2, Dxp = 2,6-(2,6-Me₂C₆H₃)₂C₆H₃) show similar disorder in one of two crystallographically independent molecules in the unit cell. A value of 2.0276(4) Å is found for the non-disordered PP bonds at 100 K for 2. A new diphosphene Ar′PPAr′ (3, Ar′ = 2,6-Mes₂-4-OMe-C₆H₃) has been prepared and its structure has also been examined. The PP bond length for 3 was determined to be 2.0326(9) Å and relatively free of the effects of disorder.     

Synthesis and structural diversity of 2-pyridylmethylideneamine complexes of zinc(II) chloride

The addition reactions of zinc(II) chloride to N-substituted pyridine-2-carbaldimines [Py-CHNR, R = Me (1a), Ph (1b), Bz (1c), allyl (1d)] lead to different complexes dependent on the N-bound substituent R. The 1:1 complexes show molecular structures of the type [(Py-CHNR)ZnCl₂] for R = methyl (2a), phenyl (2b), and allyl (2d) with a distorted tetrahedral environment for the zinc atom. The zinc complex with the N-methylated pyridine-2-carbaldimine also forms a dimer of the type [(Py-CHNR)ZnCl₂]₂ (2a)₂ with a square pyramidal coordination sphere of zinc. A 3:2 stoichiometry is observed for R = benzyl and an ion pair of the type [Zn(Py-CHNR)₃]²⁺ [ZnCl₄]²⁻ (2c) is found in the solid state.     

Ketimine synthesis in the coordination sphere of thallium (I)

[AuTl(C₆F₅)₂(en)] (en = ethylenediamine) reacts with cyclic ketones as cyclopentanone (Cy⁵O), cyclohexanone (Cy⁶O) or cycloheptanone (Cy⁷O) in 1:1 or 1:2 molar ratio leading to products of stoichiometry [AuTl(C₆F₅)₂{Cy^xN(CH₂)₂NH₂}] (x = 5 1, 6 2 or 7 3), or [AuTl(C₆F₅)₂{Cy^xN(CH₂)₂NCy^x}] (x = 5 4, 6 5 or 7 6). Addition of ethylenediamine to the ketimine complexes in chloroform regenerates [AuTl(C₆F₅)₂(en)], the starting material, and the free ketimines, as their NMR and mass spectra evidenced. The ketimine complexes display luminescence in solid state at room temperature and at 77 K at higher wavelengths than the diamine starting product (505 nm). The excited states responsible for this behaviour are assigned to orbitals due to the gold-thallium interactions.     

A new cumulene diiron complex related to the active site of Fe-only hydrogenases and its phosphine substituted derivatives: synthesis, electrochemistry and structural characterization

A new cumulene diiron complex related to the Fe-only hydrogenase active site [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₆] (1) was obtained by treatment of (μ-LiS)₂Fe₂(CO)₆ with excess 1,4-dichloro-2-butyne. By controllable CO displacement of 1 with PPh₃ and bis(diphenylphosphino)methane (dppm), mono- and di-substituted complexes, namely [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₅L] (2: L = PPh₃; 3: L = dppm) and [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₄L₂] (4: L = PPh₃; 5: L = dppm) could be prepared in moderate yields. Treatment of 1 with bis(diphenylphosphino)ethane (dppe) afforded a double butterfly complex [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₅]₂(μ-dppe) (7). With dppm in refluxing toluene, a dppm-bridged complex [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₄(μ-dppm)] (6) was obtained. These model complexes were characterized by IR, ¹H, ³¹P NMR spectra and the molecular structures of 1, 2 and 5-7 were determined by single crystal X-ray analyses. The electrochemistry of 1-3 was studied and the electrocatalytic property of 1 was investigated for proton reduction in the presence of HOAc.     

Novel long bipyridine-type linking ligands containing an intervening naphthalene fragment: [Zn(L)(NO3)2], [Zn(L)(NO3)2], and [Cd(L)1.5(NO3)2] (L = (4-py)-CHN-C10H6-NCH-(4-py); L = (3-py)-CHN-C10H6-NCH-(3-py))

Novel bipyridine-type linking ligands L¹ ((4-py)-CHN-C₁₀H₆-NCH-(4-py)) and L² ((3-py)-CHN-C₁₀H₆-NCH-(3-py)), a pair of isomers due to possessing different pairs of terminal pyridyl groups, were prepared by the Schiff-base condensation. In ligand L¹, the N?N separation between the terminal pyridyl groups is 16.0 Å, with their nitrogen donor atoms at the para positions (4,4′). The corresponding N?N separation in ligand L² is 14.2 Å, with the nitrogen donor atoms at the meta positions (3,3′). 1-D zigzag-chain coordination polymers [Zn(L¹)(NO₃)₂] (1) and [Zn(L²)(NO₃)₂] (2) were prepared by reactions of Zn(NO₃)₂ · 6H₂O with ligands L¹ and L², respectively, by solution diffusion. Polymer 3, [Cd(L¹)_1.5(NO₃)₂], prepared from Cd(NO₃)₂ · 4H₂O and L¹, exhibits a 1-D ladder structure, whose repeating ladder unit consists of four Cd metals and four L¹ ligands to create a large 76-membered ring with dimensions of 20.8 × 20.8 Å. All products were structurally characterized by X-ray diffraction.     

Syntheses, crystal structure and theoretical investigation of novel heteroleptic complexes of nickel(II) with N-R-sulfonyldithiocarbimate and phosphine ligands

Five new complexes of general formula: [Ni(RSO₂NCS₂)(dppe)], where R = C₆H₅ (1), 4-ClC₆H₄ (2), 4-BrC₆H₄ (3), 4-IC₆H₄ (4) and dppe = 1,2-bis(diphenylphosphino)ethane and [Ni(4-IC₆H₄SO₂NCS₂)(PPh₃)₂] (5), where PPh₃ = triphenylphosphine, were obtained in crystalline form by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate K₂(RSO₂NCS₂) and dppe or PPh₃ with nickel(II) chloride in ethanol/water. The elemental analyses and the IR, ¹H NMR, ¹³C NMR and ³¹P NMR spectra are consistent with the formation of the square planar nickel(II) complexes with mixed ligands. All complexes were also characterized by X-ray diffraction techniques and present a distorted cis-NiS₂P₂ square-planar configuration around the Ni atom. Quantum chemical calculations reproduced the crystallographic structures and are in accord with the spectroscopic data. Rare C-H···Ni intramolecular short contact interactions were observed in the complexes 1-5.     

Synthesis and structures of bimetallic silicon-containing imido alkylidene complexes of molybdenum Me2Si[CHMo(NAr)(ORF3)2]2 and PhVinSi[CHMo(NAr)(ORF3)2]2

Bimetallic alkylidene complexes of molybdenum (R_F3O)₂(ArN)MoCH-SiMe₂-CHMo(NAr)(OR_F3)₂ (1) and (R_F3O)₂(ArN)MoCH-SiPhVin-CHMo(NAr)(OR_F3)₂ (2) (Ar = 2,6-C₆H₃; R_F3 = CMe₂CF₃) have been prepared by the reactions of vinyl silicon reagents Me₂Si(CHCH₂)₂ and PhSi(CHCH₂)₃ with known alkylidene compound PhMe₂C-CHMo(NAr)(OR_F3)₂. Complexes 1 and 2 were structurally characterized. Ring opening metathesis polymerization (ROMP) of cyclooctene using compounds 1 and 2 as initiators led to the formation of high molecular weight polyoctenamers with predominant trans-units content in the case of 1 and predominant cis-units content in the case of 2.     

Synthesis, molecular structure, substitution and C-C coupling reactions of ruthenium complexes containing (η-C9H7)Ru(PPh3) as a molecular unit

The 2-methallyl complex [(η⁵-C₉H₇)Ru(η³-2-MeC₃H₄)(PPh₃)] (3), prepared from [(η⁵-C₉H₇)Ru(PPh₃)₂Cl] (2) and 2-MeC₃H₄MgCl, reacts with HX (X = Cl, CF₃CO₂) in the presence of ethene to give the chiral-at-metal compounds [(η⁵-C₉H₇)Ru(C₂H₄)(PPh₃)X] (4, 5) in nearly quantitative yields. Treatment of 2 with AgPF₆ and ethene affords [(η⁵-C₉H₇)Ru(C₂H₄)(PPh₃)₂]PF₆ (6), which reacts with acetone to give the substitution product [(η⁵-C₉H₇)Ru(OCMe₂)(PPh₃)₂]PF₆ (7). The molecular structure of 7 has been determined crystallographically. Whereas treatment of 4 with CH(CO₂Et)N₂ yields the olefin complex [(η⁵-C₉H₇)Ru{η²-(Z)-C₂H₂(CO₂Et)₂}(PPh₃)Cl] (8), the reactions of 4 and 5 with Ph₂CN₂, PhCHN₂ and (Me₃Si)CHN₂ lead to the formation of the carbeneruthenium(II) derivatives [(η⁵-C₉H₇)Ru(CRR′)(PPh₃)Cl] (9-11) and [(η⁵-C₉H₇)Ru(CRR′)(PPh₃)(κ¹-O₂CCF₃)] (12-14), respectively. Treatment of 9 (R = R′ = Ph), 10 (R = H, R′ = Ph) and 11 (R = H, R′ = SiMe₃) with MeLi produces the hydrido(olefin) complexes [(η⁵-C₉H₇)RuH(η²-CH₂CPh₂)(PPh₃)] (15), [(η⁵-C₉H₇)RuH(η²-CH₂CHPh)(PPh₃)] (18a,b) and [(η⁵-C₉H₇)RuH(η²-CH₂CHSiMe₃)(PPh₃)] (19) via C-C coupling and β-hydride shift. The analogous reactions of 11 with PhLi gives the η³-benzyl compound [(η⁵-C₉H₇)Ru{η³-(Me₃Si)CHC₆H₅}(PPh₃)] (20). The η³-allyl complex [(η⁵-C₉H₇)Ru(η³-1-PhC₃H₄)(PPh₃)] (17) was prepared from 10 and CH₂CHMgBr by nucleophilic attack.     

Iridium(III)-vinylidene chemistry: Conversion of an iridacyclopentadiene-chlorido complex and terminal alkynes to iridacyclopentadiene-vinyl complexes

The reactions of [κ²(C¹,C⁴)-CRCRCRCR](PPh₃)₂Ir(Cl) (9, R = CO₂Me) with propargyl alcohol derivatives (2-propyn-1-ol, 2-methyl-3-butyn-2-ol, 1-ethynylcyclopentanol, and 1-ethynylcyclooctanol), in the presence of water leads to the formation of iridium(III)-vinyl complexes bearing the general structure [κ²(C¹,C⁴)-CRCRCRCR](PPh₃)₂Ir(CO)(κ¹-vinyl) where vinyl = -CHCH₂, -(E)-CHCHMe, -CHC(CH₂)₄, or -CHC(CH₂)₇. In these, the CO ligand was derived from the terminal carbon of the starting alkyne and the oxygen atom from water. Under anhydrous conditions, 9 undergoes reaction with 2-propyn-1-ol to give trimethyl 1,3-dihydro-3-oxo-4,5,6-isobenzofurantricarboxylate, the result of a cycloaromatization/transesterification involving the buta-1,3-dien-1,4-diyl ligand in 9 and 2-propyn-1-ol.     

Synthesis and non-linear optical properties of (η-pentaphenylcyclopentadienyl)dicarbonylruthenium(II) σ-alkenyl complexes

The complexes [Ru{(Z)-HCCHPh}(CO)₂(η⁵-C₅Ph₅)] (1) and [Ru{(Z)-HCCHC₆H₄NO₂}(CO)₂(η⁵-C₅Ph₅)] (2) have been synthesized and their identity confirmed by single-crystal X-ray diffraction studies. Reaction of 2 with PMe₂Ph and Me₃NO in tetrahydrofuran afforded [Ru{(Z)-HCCHC₆H₄NO₂}(CO)(PMe₂Ph)(η⁵-C₅Ph₅)] (3). Cyclic voltammetry confirms the expected increase in ease of oxidation on proceeding from 2 to 1 and from 2 to 3. Hyper-Rayleigh scattering studies at 1064 nm reveal a dramatic increase in quadratic non-linearity on co-ligand replacement of CO by PMe₂Ph, in proceeding from 2 to 3. Z-scan studies at 800 nm are consistent with significant contribution from two-photon states, and with an increase in γ_real on co-ligand replacement of CO by PMe₂Ph in proceeding from 2 to 3.     

Synthesis and characterization of CpMCl(PR3)(S or W-η-butadienesulfonyl) compounds of rhodium and iridium

A metathesis reaction of [Cp^∗MCl₂(PR₃)] [M = Rh, R = Ph (1), Me (3); M = Ir, R = Ph (2), Me (4)] takes place in the presence of potassium butadienesulfinate (SO₂CHCHCHCH₂)K (9) to afford the mononuclear compounds [Cp^∗M(Cl)(PR₃)(η¹-SO₂CHCHCHCH₂)] [M = Rh, R = Ph (11S), (11W); M = Rh, R = Me (13S), (13W)] and [M = Ir, R = Ph (12S); M = Ir, R = Me (14S), (14W)] under different reaction conditions. The addition of PR₃ (R = Ph, Me) to Cp^∗Ir(Cl)[(1,2,5-η)-SO₂CHCHCHCH₂] (7) affords the corresponding iridium isomers 12S, 12W and 14S, in a non-selective reaction, along with the corresponding dichloride compounds 2 or 4. The ¹H and ¹³C{¹H} NMR data are consistent with the butadienesulfonyl ligands coordinated exclusively through the sulfur atom, and they show the presence of two isomers, described as the S and W conformers, which can be isolated separately. There is clear evidence that these isomers correspond to the kinetic and thermodynamic derivatives, respectively.     

Oxidovanadium(IV) complexes containing ligands derived from dithiocarbazates - Models for the interaction of VO with thiofunctional ligands

The tetragonal-pyramidal VO²⁺ complexes [VO{(RSC-S)N-NX}₂] (1-6) were synthesised by the reactions of VO(OCHMe₂)₃ with the dithiocarbazate ligands RSC(S)-NH-NX, where X = cyclo-pentyl, cyclo-hexyl or 4-Me₂N-C₆H₄-CH, and R = CH₃ or CH₂C₆H₅. The compounds were characterised by elemental analysis, IR- and mass spectrometries, and in cases of compounds 1, 3, 4 and 5, by X-ray diffraction. The chiral compound 4 (X = cyclo-hexyl, R = CH₂C₆H₅) crystallises in the C configuration. In compound 5, the VO moiety is disordered (83.3:16.7%) with respect to the plane spanned by the four equatorial ligand functions.     

Ferrocenyl-substituted allenylidene complexes of chromium, molybdenum and tungsten: Synthesis, structure and reactivity

Bis(ferrocenyl)-substituted allenylidene complexes, [(CO)₅MCCCFc₂] (1a-c, Fc = (C₅H₄)Fe(C₅H₅), M = Cr (a), Mo (b), W (c)) were obtained by sequential reaction of Fc₂CO with Me₃Si-CCH, KF/MeOH, n-BuLi, and [(CO)₅M(THF)]. For the synthesis of related mono(ferrocenyl)allenylidene chromium complexes, [(CO)₅CrCCC(Fc)R] (R = Ph, NMe₂), three different routes were developed: (a) reaction of the deprotonated propargylic alcohol HCCC(Fc)(Ph)OH with [(CO)₅Cr(THF)] followed by desoxygenation with Cl₂CO, (b) Lewis acid induced alcohol elimination from alkenyl(alkoxy)carbene complexes, [(CO)₅CrC(OR)CHC(NMe₂)Fc], and (c) replacement of OMe in [(CO)₅CrCCC(OMe)NMe₂] by Fc. Complex 1a was also formed when the mono(ferrocenyl)allenylidene complex [(CO)₅CrCCC(Fc)NMe₂] was treated first with Li[Fc] and the resulting adduct then with SiO₂. The replacement route (c) was also applied to the synthesis of an allenylidene complex (7a) with a CC spacer in between the ferrocenyl unit and C_γ of the allenylidene ligand, [(CO)₅CrCCC(NMe₂)-CCFc]. The related complex containing a CHCH spacer (9a) was prepared by condensation of [(CO)₅CrCCC(Me)NMe₂] with formylferrocene in the presence of NEt₃. The bis(ferrocenyl)-substituted allenylidene complexes 1a-c added HNMe₂ across the C_α-C_β bond to give alkenyl(dimethylamino)carbene complexes and reacted with diethylaminopropyne by regioselective insertion of the CC bond into the C_β-C_γ bond to afford alkenyl(diethylamino)allenylidene complexes, [(CO)₅MCCC(NEt₂)CMeCFc₂]. The structures of 5a, 7a, and 9a were established by X-ray diffraction studies.     

Cyclodiphosph(III)azane chemistry - Ylides from the reaction of [(RNH)P-N(t-Bu)]2 [R = t-Bu, i-Pr] with dimethyl maleate and chiral ansa-type derivatives from reaction of [ClP-N(t-Bu)]2 with a substituted BINOL

Use of a simple inorganic ring system with the cyclodiphosph(III)azane skeleton [e.g. [(RNH)P-N(t-Bu)]₂ [R = t-Bu (7), i-Pr (8)] to probe some of the intermediates proposed in phosphine mediated organic reactions is highlighted. Thus the reaction of 7-8 with the allenylphosphine oxide Ph₂P(O)C(Ph)CCH₂ (9) affords the phosphinimines [(RNH)P(μ-N-t-Bu)₂P(N-R)-C(CH₂)CH(Ph)-P(O)Ph₂] [R = t-Bu (10), i-Pr (11)], while a similar reaction of 7-8 with dimethyl maleate (or dimethyl fumarate) affords the ylides [(RNH)P(μ-N-t-Bu)₂P(NH-R)C(CO₂Me)-CH₂(CO₂Me) [R = t-Bu (18), i-Pr (19)]. The implication of such reactions on phosphine mediated organic transformations including Morita-Baylis-Hillman reaction is mentioned. In a rather rare type of situation, an unusually long phosphoryl (PO) bond [1.538 (5) Å] as revealed the X-ray structure of {(R)-6,6′-(t-Bu)₂-1,1′-(C₁₀H₅)₂-2,2′-O₂-}{P(O)(N-t-Bu)₂-P(Se)} (27) is rationalized by means of crystallographic disorder in packing after comparing the data with that in the literature and {1,1′-(C₁₀H₆)₂-2,2′-O₂}{P(Se)(N-t-Bu)₂-P(Se)} (29). X-ray structures of the new compounds 10-11, 18-19, 27 and 29 are discussed. Compound 10 crystallizes in the chiral space group Pca2(1) with (S)-chirality at the carbon center [-C(CH₂)CH(Ph)-P] suggesting a case of spontaneous resolution through crystallization.     

Cytotoxic studies of substituted titanocene and ansa-titanocene anticancer drugs

A variety of substituted titanocene and ansa-titanocene complexes have been synthesized and characterized using traditional methods. The cytotoxic activity of the different titanocene complexes was tested against tumour cell lines human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x and normal immunocompetent cells, peripheral blood mononuclear cells PBMC. Alkenyl substitution, either on the cyclopentadienyl ring or on the silicon-atom ansa-bridge of the titanocene compounds [Ti{Me₂Si(η⁵-C₅Me₄)(η⁵-C₅H₃{CMe₂CH₂CH₂CHCH₂})}Cl₂] (8), [Ti{Me(CH₂CH)Si(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] (9) and [Ti(η⁵-C₅H₄{CMe₂CH₂CH₂CHCH₂})₂Cl₂] (12) showed higher cytotoxic activities (IC₅₀ values from 24 ± 3 to 151 ± 10 μM) relative to complexes bearing an additional alkenyl-substituted silyl substituent on the silicon bridge [Ti{Me{(CH₂CH)Me₂SiCH₂CH₂}Si(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] (10) and [Ti{Me{(CH₂CH)₃SiCH₂CH₂}Si(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] (11) which causes a dramatic decrease of the cytotoxicity (IC₅₀ values from 155 ± 9 to >200 μM). In addition, the synthesis of the analogous niobocene complex [Nb(η⁵-C₅H₄{CMe₂CH₂CH₂CH=CH₂})₂Cl₂] (13), is described. Structural studies based on DFT calculations of the most active complexes 8, 9 and 12 and the X-ray crystal structure of 13 are reported.     

Organometallic π-tweezers incorporating pyrazine- and pyridine-based bridging units

Pyrazine- and pyridine-based π-conjugated σ-donor molecules, such as 4,4′-bipyridine, 1,2-di(4-pyridyl)ethylene, 3,5-dipyridyl-1,2,4-triazole, N,N′-bis(4-pyridylmethylidene)benzene-1,4-diamine, 2,5-di(pyridylmethylidene)cyclopentanone, 2,6-di(4-pyridylmethylidene)cyclohexanone (LL, 2a-2g) can successfully be used to span heterobimetallic π-tweezer units of the type [{[Ti](μ-σ,π-CCSiMe₃)₂}M]⁺ ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; M = Cu, Ag). The thus accessible di-cationic species [{[Ti](μ-σ,π-CCSiMe₃)₂}MLLM{(Me₃SiCC-μ-σ,π)₂[Ti]}]²⁺ (4), which are formed via the formation of [{[Ti](μ-σ,π-CCSiMe₃)₂}MLL]⁺ (3) complexes, can be isolated in yields between 66% and 99%.However, when C₅H₄NCHCHC₆H₄CHCHNC₅H₄ (5a) and C₅H₄NCHNC₆H₄CHCHNC₅H₄ (5b), respectively, are reacted with {[Ti](μ-σ,π-CCSiMe₃)₂}AgBF₄(1c) in a 1:1 molar ratio, then the silver(I) ion is released from the organometallic π-tweezer 1c and coordination polymers [AgBF₄ · 5a]_n (6a) and [AgBF₄ · 5b]_n (6b) along with [Ti](CCSiMe₃)₂ (7) are formed in quantitative yield.     

Syntheses, crystal structure, spectroscopic characterization and antifungal activity of new N-R-sulfonyldithiocarbimate metal complexes

Five new compounds with the general formula of (Bu₄N)₂[M(RSO₂NCS₂)₂], where Bu₄N = tetrabutylammonium cation, (M = Ni, R = 4-FC₆H₄) (1), (M = Zn, R = 4-FC₆H₄, 4-ClC₆H₄, 4-BrC₆H₄, 4-IC₆H₄), (2), (3), (4) and (5), respectively, were obtained by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO₂NCS₂K₂) with nickel(II) chloride hexahydrate or zinc(II) acetate dihydrate in metanol:water 1:1. The elemental analyses and the IR data are consistent with the formation of the expected bis(dithiocarbimato)metal(II) complexes. The ¹H and ¹³C NMR spectra showed the signals for the tetrabutylammonium cation and the dithiocarbimate moieties. The compounds 1, 2 and 5 were also characterized by X-ray diffraction techniques. The nickel(II) is coordinated by two N-4-fluorophenylsulphonyldithiocarbimato(2-) ligands forming a planar coordination. The zinc(II) exhibits distorted tetrahedral configuration in compounds 2 and 5 due to the chelation effect of two sulfur atoms of the N-R-sulfonyldithiocarbimate ligands. The antifungal activities of the compounds were tested in vitro against Colletotrichum gloeosporioides, an important fungus that causes the plant disease known as anthracnose in fruit trees. All the complexes were active.     

Addition of protic nucleophiles to alkynyl methoxy carbene ligands in diiron complexes

Different protic nucleophiles (i.e.Ph₂CNH, PhSH, MeCO₂H, PhOH) can be added to the CC bond of [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C(OMe)CCTol}(Cp)₂][SO₃CF₃] (1), affording new diiron alkenyl methoxy carbene complexes.The additions of Ph₂CNH and MeCO₂H are regio and stereoselective, resulting in the formation of the 5-aza-1-metalla-1,3,5-hexatriene [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C_α(OMe)C_βHC_γ(Tol)(NCPh₂)}(Cp)₂][SO₃CF₃] (2), and the 2-(acyloxy)alkenyl methoxy carbene complex [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C_α(OMe)C_βHC_γ(Tol)OC(O)Me)}(Cp)₂][CF₃SO₃] (5); the E isomer of the former and the Z of the latter are formed exclusively.Conversely, the addition of PhSH is regio but not stereoselective; thus, both the E and Z isomers of [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C_α(OMe)C_βHC_γ(Tol)(SPh)}(Cp)₂][SO₃CF₃] (3) are formed in comparable amounts.Compounds 3 and 5 are demethylated upon chromatography through Al₂O₃, resulting in the formation of the acyl complexes [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C_α(O)C_βHC_γ(Tol)(SPh)}(Cp)₂] (4) and [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C_α(O)C_βHC_γ(Tol)OC(O)Me}(Cp)₂] (6), respectively, both with a Z configured C_βC_γ bond.Finally, the reaction of 1 with PhOH proceeds only in the presence of an excess of Et₃N affording the 2-(alkoxy)alkenyl acyl complex [Fe₂{μ-CN(Me)(Xyl)}(μ- CO)(CO){C_α(O)C_βHC_γ(Tol)(OPh)}(Cp)₂] (7). The crystal structures of 4 · CH₂Cl₂ and 7 · 0.5CH₂Cl₂ have been determined by X-ray diffraction experiments.