Chain-transfer catalysis by vanadium complexes during methyl methacrylate polymerization

A series of V(CO)₄(P-P) or HV(CO)₄(P-P) ((P-P) = bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), and 1,4-bis(diphenylphosphino)butane (dppb)) complexes have been tested as chain-transfer catalysts for methyl methacrylate (MMA) polymerization. The chain transfer constants C_s (=k_tr/k_p), determined by Mayo plots, suggest that V(CO)₄(dppe) is the most efficient chain-transfer catalyst among the complexes investigated (C_s = 750 at 70 °C).     

Heteroleptic Cu(I) complexes containing phenanthroline-type and 1,1′-bis(diphenylphosphino)ferrocene ligands: Structure and electronic properties

Three new heteroleptic Cu(I) complexes containing one phenanthroline and one diphosphine type ligand ([Cu(N-N)(P-P)]⁺) have been prepared. In particular, one ligand is constituted by 1,10-phenanthroline (1), 2,9-dimethyl-1,10-phenanthroline (2) and 2,9-diphenethyl-1,10-phenanthroline (3) and the other ligand is in all cases 1,1′-bis(diphenylphosphino)ferrocene (dppf). Therefore, copper and iron metal centres are quite close one another, as evidenced by X-ray crystal diffraction. The structure together with the electrochemical and photophysical properties of these complexes have been compared to that of the corresponding complexes where dppf has been replaced by bis[2-(diphenylphosphino)-phenyl]ether (POP). Cyclic voltammetric experiments evidenced that the first oxidation process is located on the ferrocene moiety and that oxidation of Cu(I) is moved to more positive potential values and a chemical reaction is coupled to the electron transfer process. The absorption spectra show a metal-to-ligand charge transfer (MLCT) band, typical of Cu(I) phenanthroline complexes, at a higher energy compared to the homoleptic [Cu(N-N)₂]⁺ species. No emission at either room temperature or 77 K has been observed for compounds 2 and 3, contrary to the high luminescence observed for the corresponding POP complexes. This result is consistent with a photoinduced energy transfer from the Cu(I) complex to the ferrocene moiety.     

Synthesis and optical properties of binuclear gold(I) complexes with bridging phosphine ligands: luminescence from intraligand and metal-centered excited states

The complexes Au₂Cl₂(P-P) with P-P=biphep (2,2^′-bis(diphenylphosphino)-1,1^′-biphenyl), binap (2,2^′-bis(diphenylphosphino)-1,1^′-binaphthyl) and xantphos (9,9^′-dimethyl-4,5-bis(diphenyl-phosphino)xanthene), were prepared and characterized by elemental analysis and ESI-MS. The solid compounds show a r.t. phosphorescence. While the binap complex emits from an intraligand (IL) triplet, the luminescence of the biphep complex originates from a metal-centered (MC) triplet which is presumably lowered by gold-gold interaction. The xantphos complex displays a dual phosphorescence. In this case, the emitting triplets are of the IL and MC type.     

Enantioselective hydrogenation of olefins with phosphinooxazoline-iridium catalysts

Cationic iridium complexes with chiral phosphinooxazoline ligands are efficient catalysts for the enantioselective hydrogenation of olefins. The complexes are readily prepared, air-stable, and easy to handle. In contrast to chiral rhodium- and ruthenium-phosphine catalysts, they do not require the presence of a polar coordinating group near the C=C bond. In the hydrogenation of unfunctionalized trisubstituted 1,2-diaryl-olefins, high enantioselectivities of >95% ee with full conversion and turnover frequencies of >7,000 h-1 can be achieved, using 0.1 mol% of catalyst with tetrakis[3, 5-bis(trifluoromethyl)phenyl]borate (TFPB or BARF) as the counterion. The corresponding hexafluorophosphate or tetrafluoroborate salts give low conversion due to deactivation of the catalyst during the reaction. Substrates with polar substituents such as allylic alcohols, on the other hand, afford better results with the hexafluorophosphate salts.     

Gold(I) and silver(I) complexes of 2,3-bis(diphenylphosphino)maleic acid: Structural studies and antitumour activity

The 2:1 and 1:2 adducts of Au(I) and 1:2 adducts of Ag(I) with the diphosphine 2,3-bis(diphenylphosphino)maleic acid (dpmaa) have been prepared in high yields. Crystal structures have been determined for the neutral digold complex (AuCl)₂(dpmaa) · 2thf (1) and the bis-chelated complex [Au(dpmaa)₂]Cl · H₂O · CH₃OH (2). For 1, conformational rigidity imposed by the ethylenic bridge facilitates the formation of short intramolecular Au-Au contacts with no evidence of similar intermolecular contacts. Complex 2 crystallizes with [Au(dpmaa)₂]⁺ cations hydrogen bonded through the carboxyl groups to a water molecule and chloride anion to form a H-bonded chain along the a axis. ³¹P NMR titration of 1 with dpmaa in acetone shows conversion to 2 at Au:P-P ratios less than 1:1 indicating similar high thermodynamic and kinetic stabilities to other bis-chelated [Au(P-P)₂]⁺ complexes containing 5- or 6-membered chelate rings. The ionic Au(I) complex 2 and the analogous Ag(I) complex [Ag(dpmma)₂]NO₃ (3) are highly water soluble. The in vitro cytotoxic activity of 2 was assessed against eight different cell lines and no significant activity was found. The solubility properties and solution behaviour of the complexes are compared to the analogous 1,2-bis(diphenylphosphino)ethane (dppe) complexes and the potential significance of these results to the antitumour properties of chelated 1:2 Au(I)diphosphine complexes are discussed.     

Platinum(II) diphosphine complexes as catalysts for the Baeyer-Villiger oxidation of ketones: Is it possible to increase the concentration of the active species?

The synthesis and characterization of new bis-aquo platinum(II) complexes of the type [Pt(H₂O)(P-P)][OTf]₂ (OTf = triflate anion), in which the diphosphine P-P is a series of 1,n-bis-diphenyphosphinoalkanes (1a-d, with n = 1-4), 1,2-bis-(di-n-fluorophenylphosphino)ethanes (2a-c, with n = 2, 4-5) and 1,2-bis-dialkylphosphinoethanes (3a-e), where the alkyl substituents at phosphorus have been systematically changed (dmpe) (3a), (depe) (3b), (dippe) (3c), (dcype) (3d) are reported. These complexes were used as catalysts in the Baeyer-Villiger oxidation of 2-methylcyclohexanone, 2-methylcyclopentanone and cyclobutanone with 35% hydrogen peroxide as an environmentally friendly oxidant. The reactions were performed at 25 °C in a chlorinated solvent/H₂O two-phase system. All the investigated catalysts performed better than the corresponding dimeric complexes of general formula [Pt(μ-OH)(P-P)]₂[BF₄]₂ as a consequence of the positive effect imparted by the triflate counter-anion on catalysts speciation.     

Cytotoxicity of half sandwich ruthenium(II) complexes with strong hydrogen bond acceptor ligands and their mechanism of action

Neutral and cationic organometallic ruthenium(II) piano stool complexes of the type [(η⁶-cymene)RuCl(X)(Y)] (complexes R1-R8) has been synthesized and characterized. In cationic complexes, X, Y is either a η² phosphorus ligand such as 1,1-bis(diphenylphosphino)methane (DPPM) and 1,2-bis(diphenylphosphino)ethane (DPPE) or partially oxidized ligands such as 1,2-bis(diphenylphosphino)methane monooxide (DPPMO) and 1,2-bis(diphenylphosphino)ethane monooxide (DPPEO) which are strong hydrogen bond acceptors. In neutral complexes, X is chloride and Y is a monodentate phosphorous donor. Complexes with DPPM and DPPMO ligands ([(η⁶-cymene)Ru(η²-DPPM)Cl]PF₆ (R2), [(η⁶-cymene)Ru(η²-DPPMO)Cl]PF₆ (R3), [(η⁶-cymene)Ru(η¹-DPPM)Cl₂] (R5) and [(η⁶-cymene)Ru(η¹-DPPMO)Cl₂] (R6) show good cytotoxicity. Growth inhibition study of several human cancer cell lines by these complexes has been carried out. Mechanistic studies for R5 and R6 show that inhibition of cancer cell growth involves both cell cycle arrest and apoptosis induction. Using an apoptosis PCR array, we identified the sets of anti-apoptotic genes that were down regulated and pro-apoptotic genes that were up regulated. These complexes were also found to be potent metastasis inhibitors as they prevented cell invasion through matrigel. The complexes were shown to bind DNA in a non intercalative fashion and cause unwinding of plasmid DNA in cell-free medium by competitive ethidium bromide binding, viscosity measurements, thermal denaturation and gel mobility shift assays.     

New chiral catalysts for reduction of ketones

The condensation of o-(diphenylphosphino)benzaldehyde and various chiral diamine gives a series of diimino-diphosphine tetradentate ligands, which are reduced with excess NaBH4 in refluxing ethanol to afford the corresponding diaminodiphosphine ligands in good yield. The reactivity of these ligands toward trans-RuCl2(DMSO)4 and [Rh(COD)Cl]2 had been investigated and a number of chiral Ru(II) and Rh(I) complexes with the PNNP-type ligands were synthesized and characterized by microanalysis and IR, NMR spectroscopic methods. The chiral Ru(II) and Rh(I) complexes have proved to be excellent catalyst precursors for the asymmetric transfer hydrogenation of aromatic ketones, leading to optically active alcohols in up to 97% ee.     

Synthesis of non proteinogenic dipeptides by asymmetric hydrogenation

Summary N-Boc protected non-proteinogenic dipeptides with D,L-and L,L-configuration were prepared by catalytic asymmetric hydrogenation of the corresponding dehydrophenylalanyl-(L)-phenylalanine derivatives. The configuration of the new stereogenic centre depends first of all on the catalyst configuration and is less influenced by the substrate configuration. Diastereomeric excesses in the range of 80–96% de could be increased up to 99% by recrystallization. Analytical data of selected new compounds are given.Abbreviations PINDOPHOS 2,3-O,N-bis(diphenylphosphino)-1-(4-indolyloxy)-2-hydroxy-3-isopropylamino propane - PROPRAPHOS 2,3-O,N-bis(diphenylphosphino)-1-(naphthoxy)-2-hydroxy-3-isopropylamino propane - BDPB 1,4-bis(diphenylphosphino)butane     

A practical route to partially protected pyrrolidines as precursors for the stereoselective synthesis of alexines

Either 3-O-benzoyl- (2a) or 3-O-benzyl-1,2-O-isopropylidene-beta-D-fructopyranose (2b) were regioselectively O-benzylated at C-4 to give 4a and 4b, respectively, which were transformed into 5-azido-3-O-benzoyl-4-O-benzyl- (6a) and 5-azido-3,4-di-O-benzyl-5-deoxy-1,2-O-isopropylidene-alpha-L-sorbopyranose (6b) by nucleophilic displacement of the corresponding 5-O-mesyl derivatives 5a and 5b by sodium azide in DMF, respectively. Compound 6b was also prepared from 4b in one step by the Mitsunobu methodology. Deacetonation of 6a and 6b gave the partially protected free azidouloses 8a and 8b, respectively, that were protected as their 1-O-TBDPS derivatives 9a and 9b. Hydrogenation of 9b over Raney nickel gave stereoselectively (2R,3R,4R,5S)-3,4-dibenzyloxy-2'-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (12) which was identified by transformation into the well known (2R,3R,4R,5S)-3,4-dihydroxy-2,5-bis(hydroxymethyl)pyrrolidine (1, DGDP).     

Photophysical properties, X-ray structures, electrochemistry, and DFT computational chemistry of osmium complexes

We report the synthesis of phosphorescent divalent osmium complexes of the form [Os(N-N)₂(L-L) or Os(L-L)₂(N-N)]²⁺ (PF₆)₂ where N-N is a derivative of 1,10-phenanthroline, and L-L is a diarsine or diphosphine ligand: 1,2-bis(dimethylphosphino)ethane, 1,2-bis(dicyclohexylphosphino)ethane, or 1,2-bis(dimethylarseno)benzene. X-ray structures have been determined, luminescent and electrochemical properties have been measured and DFT calculations have been performed on the complexes. The emission lifetime of complexes of structure Os(II)(L-L)₂(N-N) are longer than the those of Os(II)(N-N)₂(L-L). The DFT calculations show that there is significant mixing of the π−π^∗ into the dπ−π^∗ charge-transfer state for the complexes of the form Os(II)(L-L)₂(N-N) resulting in a longer lived excited state. Through DFT calculations we were able to conclude that the HOMO of the complexes is a d orbital on the osmium while the LUMO is the b₁(ψ) π^∗ system of the phenanthroline. However, we found that the HOMO did not have the correct symmetry to enable strong charge transfer to the phenanthroline to be observed, and the strong MLCT transition observed in the spectra is the metal d HOMO(−1) to the b1 π^∗ LUMO of the phenanthroline.     

Synthesis and electrochemistry of Co(III) and Co(I) complexes having C5Me5 auxiliary

The synthesis and electrochemistry of half-sandwich type of Co(III) complexes [(C(5)Me(5))Co(bidentate)(CH(3)CN)](BF(4))(2) {bidentate=dppe (1,2-bis(diphenylphosphino)ethane), dppp (1,3-bis(diphenylphosphino)propane), bpy (2,2'-bipyridine), en (ethylenediamine)) are reported. Cyclic voltammograms of [(C(5)Me(5))Co(bidentate)(CH(3)CN)](BF(4))(2) in CH(3)CN s showed two redox couples assignable to Co(II)/Co(III) and Co(I)/Co(II). The Co(I) complex having C(5)Me(5) and dppe was also prepared. Two redox couples of this Co(I) complex, (C(5)Me(5))Co(dppe), in CH(3)CN coincided with those of [(C(5)Me(5))Co(dppe)(CH(3)CN)](BF(4))(2) in spite of the structural change around the metal center.     

Antimetastatic properties and DNA interactions of the novel class of dimeric Ru(III) compounds Na2[[trans-RuCl4(Me2SO)]2(mu-L)] (L = ditopic, non-chelating aromatic N-ligand). A preliminary investigation

A novel class of dianionic Ru(III) dimers of formula Na2[[trans-RuCl4(Me2SO)]2(mu-L)], with L = pyrazine (pyz, 1), pyrimidine (pym, 2), 4,4'-bipyridine (bipy, 3), and 1,2-bis(4-pyridine) ethane (etbipy, 4), was developed by us with the specific aim of assessing their antitumor properties. The dimers are in fact structurally related to the antimetastatic mononuclear compound (ImH) [trans-RuCl4(Me2SO)(Im)] (NAMI-A, Im = imidazole). Preliminary results concerning the antineoplastic activity of 1-4 against the murine MCa carcinoma model, a tumor which spontaneously metastasizes in the lungs, are reported. Similarly to what is normally observed with NAMI-A, the treatment with the dimeric complexes was scarcely effective against the growth of the primary tumor. However, dimers 1, 2, and 4 reduced very effectively the number and, in particular, the weight of lung metastases (to about 5% with respect to controls); in particular, Na2[[trans-RuCl4(Me2SO)]2(mu-etbipy)] (4) was as effective as NAMI-A in reducing the spontaneous metastases at a dosage which, in terms of moles of ruthenium, is about 3.5 times lower compared to that normally used for NAMI-A. Furthermore, in vitro tests showed that dimers 1-4 are capable of forming interstrand cross-links with linearized plasmidic DNA in a time-dependent manner. All the dimeric species are more active in inducing cross-links compared to NAMI-A, and the dimer bridged by the etbipy ligand (4) is the most effective among those tested.     

Regio- and stereoselective cyclizations of dianhydro sugar alcohols catalyzed by a chiral (salen)Co(III) complex

The (salen)Co(III)OAc ((R,R)-1 and (S,S)-1) catalyzed cyclizations of the chiral dianhydro sugars, 1,2:5,6-dianhydro-3,4-di-O-methyl-D-glucitol (2), 1,2:5,6-dianhydro-3,4-di-O-methyl-D-mannitol (3), 1,2:5,6-dianhydro-3,4-di-O-methyl-L-iditol (4), and 1,2:4,5-dianhydro-3-O-methyl-L-arabinitol (5), is a facile method for the synthesis of anhydroalditol alcohols. Cyclization of 2 using (R,R)-1 and (S,S)-1 proceeded diastereoselectively to form 2,5-anhydro-3,4-di-O-methyl-D-mannitol (6) and 2,5-anhydro-3,4-di-O-methyl-L-iditol (7), respectively. The cyclization of 3 and 5 is a novel method for obtaining 1,6-anhydro-3,4-di-O-methyl-D-mannitol (11) and a stereoselective route to 1,5-anhydro-3-O-methyl-L-arabinitol (13). It is proposed that the reaction occurs via endo-selective cyclization of an epoxy alcohol produced by the endo-selective ring-opening of one of the two epoxide moieties in the starting material.     

Synthetic studies towards a new scaffold, spirobicycloimidazoline

A new scaffold consisting of a carbocycle and a substituted imidazoline in an orthogonal arrangement was synthesized as a potential specific inhibitor of glycosidases. The spirobicycloimidazoline, (5R,6R,7R,8R)-8-(hydroxymethyl)-2-phenyl-1,3-diazaspiro[4.4]non-1-ene-6,7-diol, was synthesized from methyl 2-O-p-methoxybenzyl-3,4-di-O-benzyl-alpha/beta-D-gluco-6-enopyranoside via (1R,2S,3S,4R,5S)-3,4-bis(benzyloxy)-2-(4-methoxybenzyloxy)-5-vinyl-cyclopentanol. The ring contraction of the 6-enopyranoside in the presence of zirconocene equivalent ('Cp(2)Zr') reagent gave exclusively the corresponding cyclopentanol without cleavage of the PMB protecting group. In the course of the study, a new alpha-mannosidase inhibitor, (1R,2R,3R,5R)-5-amino-3-hydroxymethyl-cyclopentane-1,2-diol, was also discovered.     

Synthesis of non-proteinogenic (D)- or (L)-amino acids by asymmetric hydrogenation

Summary Non-proteinogenic amino acids play an increasing role in oligopeptide chemistry. Their pharmacological and chemical properties, caused by D-configuration and unnatural residues, are more and more used for drug design. Different methods of asymmetric synthesis have been developed during the last decade to prepare unusual amino acids. One of them, the asymmetric hydrogenation of dehydroamino aids catalyzed by chiral rhodium (I) complexes, will be described. A series of examples, D- and L-configured, like naphthyl-, thienyl-, furyl-, and pyridylalanines, as well as phenylalanines substituted by chlorine, fluorine, p-nitro, p-methyl, p-trifluoromethyl, p-isopropyl, and p-tert-butyl have been prepared and characterized. Some analytical data like melting points and values of optical rotation are summarized in tables.Abbreviations (–)-DIOP (4R,5R)-4,5-Bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxolane - (–)-BPPM (2S,4S)-N-tert-Butoxycarbonyl-4-diphenylphosphino-2-diphenylphosphinomethyl-pyrrolidine - Ph--glup Phenyl 4,6-O-(R)-benzylidene-2,3-O-bis(diphenylphosphino)--D-glucopyranoside - DuPHOS 1,2-bis-(phospholano)benzene - PROPRAPHOS 2,3-O,N-bis(diphenylphosphino)-1-(naphthoxy)-2-hydroxy-3-isopropylamino propane - PINDOPHOS 2,3-O,N-bis(diphenylphosphino)-1-(4-indolyloxy)-2-hydroxy-3-isopropylamino propane     

Reaction of trans-4-N-acetoxy-N-acetylaminostilbene with guanosine and deoxyguanosine in vitro: the primary reaction product at N2 of guanine yields different final adducts

The model ultimate carcinogen, trans-4-N-acetoxy-N-acetylaminostilbene (N-acetoxy-AAS), was reacted with guanosine (Guo) and deoxyguanosine (d-Guo) and the resulting adducts were purified by Sephadex LH-20 chromatography and HPLC for structure identification. A number of new adducts was identified by mass and 1H-NMR spectroscopy. The generation of all known adducts can now be explained by a common mechanism. The electrophile formed from the hydroxamic acid ester at C-beta reacts in a first step predominantly with N2 of guanine (Gua). The resulting quinone-imide intermediate reacts in a second step with either one of three nucleophiles: (1) predominantly with N3 of Gua to yield the previously described angular cyclic adducts ((5R,6R)/(5S,6S)-9-oxo-5,6,7,9-tetrahydro-imidazo(2,1-b)purines); (2) with N1 of Gua to yield linear cyclic adducts ((6R,7R)/(6S,7S)-9-oxo-5,6,7,9-tetrahydro-imidazo(1,2-a)purines); (3) with water to yield the open ring (1R,2R)/(1S,2S)-2-(N2'-guanyl)-1-hydroxyethanes. To some minor extent (1:8-1:9) the electrophile reacts first with N1 or N3 of guanine which leads to the formation of two pairs of the corresponding regioisomeric cyclic adducts. This reaction mechanism may also explain the formation of cross-links between different bases.     

Synthesis and antimalarial activities of rhenium bioorganometallics based on the 4-aminoquinoline structure

A bioorganometallic approach to malaria therapy led to the discovery of ferroquine (FQ, SSR97193). To assess the importance of the electronic properties of the ferrocenyl group, cyclopentadienyltricarbonylrhenium analogues related to FQ, were synthesized. The reaction of [N-(7-chloro-4-quinolinyl)-1,2-ethanodiamine] with the cyrhetrenylaldehyde complexes (η(5)-C(5)H(4)CHO)Re(CO)(3) and [η(5)-1,2-C(5)H(3)(CH(2)OH)(CHO)]Re(CO)(3) produces the corresponding imine derivatives [η(5)-1,2-C(5)H(3)(R)(CHN-CH(2)CH(2)NH-QN)]Re(CO)(3) R=H 3a; R=CH(2)OH 3b; QN=N-(7-Cl-4-quinolinyl). Reduction of 3a and 3b with sodium borohydride in methanol yields quantitatively the amine complexes [η(5)-1,2-C(5)H(3)(R)(CH(2)-NH-CH(2)CH(2)NH-QN)]Re(CO)(3) R=H 4a; R=CH(2)OH 4b. To establish the role of the cyrethrenyl moiety in the antimalarial activity of this series, purely organic parent compounds were also synthesized and tested. Evaluation of antimalarial activity measured in vitro against the CQ-resistant strains (W2) and the CQ-susceptible strain (3D7) of Plasmodium falciparum indicates that these cyrhetrene conjugates are less active compared to their ferrocene and organic analogues. These data suggest an original mode-of-action of FQ and ferrocenyl analogues in relationship with the redox pharmacophore.     

Synthesis, characterization and reactivity of platinum-substituted ketenes [PtX{η-C(PPh3)CO}L2]BF4, (X=Me, Cl; L2=1,5-cyclooctadiene, 1,2-bis(diphenylphosphino)ethane, cis-1,2-bis(diphenylphosphino)ethene). Steric and electronic effects of the ancillary ligands

Ketenylidenetriphenylphosphorane, Ph₃PC=C=O, 1, has been used to synthesize platinum-substituted ketenes [PtMe{η¹-C(PPh₃)CO}L₂]BF₄, 2a, b (L₂=1,5-cyclooctadiene, cod (a), 1,2-bis(diphenylphosphino)ethane, diphos (b)). Parent compound [PtCl{η¹-C(PPh₃)CO}L₂]BF₄, 3, with L₂=cis-1,2-bis(diphenylphosphino)ethene, diphoe, was also synthesized, which is stable only at low temperature. The stability of 2 and 3 and the reactivity of the C=C=O moiety have been examined and discussed in terms of the electronic and steric characteristics of the ancillary ligands, also taking into account the reactivity of the ‘PtXL₂’ fragment with other carbonyl stabilized phosphorus ylides, Ph₃PCHCOR (R=Me, Ph, OMe, OEt).     

Diphosphines as bridging ligands in polymeric and dimeric thione-S-ligated Ag(I) nitrate complexes

Reactions of silver(I) nitrate with equimolar amounts of the diphos ligands 1,4-bis(diphenylphosphino)butane (dppb) or 1,2-bis(diphenylphosphino)ethane (dppe) and some heterocyclic thiones (L) in acetonitrile/methanol solvent afforded mixed-ligand complexes, the nature of which was found to be strongly influenced by the backbone length of the diphosphine ligand. The longer chained diphos ligand formed a series of dinuclear complexes of the type [Ag(dppb)(L)]₂(NO₃)₂ with both the diphosphine and thione ligands acting as bridging ligands between the two four-coordinate pseudo-tetrahedrally coordinated metal centers. In the unique case of L=4-methyl-5-trifluoromethyl-4H-1,2,4-triazoline-3(2H)-thione (mftztH), the reaction proceeded under exclusion of the thione ligand from the coordination sphere and coordination of the nitrate anions instead, leading to the diphosphine-doubly bridged dimeric compound [Ag(dppb)(NO₃)]₂. On the other hand, the complexes produced when using the short bite 1,2-bis(diphenylphosphino)ethane (dppe) turned out to be diphosphine-bridged cationic polymers of the type [Ag(dppe)(L)₂]_n(NO₃)_n. The structures of one representative for each of the two aforementioned series of complex compounds, namely [Ag(dppb)(py2SH)]₂(NO₃)₂ · 2H₂O and [Ag(dppe)(pymtH)₂]_n(NO₃)_n, have been established by single-crystal X-ray diffraction.