N,N′-diisobutyloxycarbonyl-N″,N‴-(1,3-propylene)-bisthiourea (L) and its silver(I) and gold(I) complexes were designed and synthesized. Treatment of 1,3-propanediamine with the isothiocyanate iPrCH2OC(O)NCS yielded bisthiourea L with over 90% yield. Treatment of L with AgNO3 in CH3CN afforded coordination polymer {[Ag(L)(NO3)·CH3CN]}n (1) with layer structure, while with HAuCl4 in CH3CN resulted in reduction of Au3+ to Au+ to yield molecular [Au(L)Cl] (2). Ligand L and complexes 1 and 2 were fully characterized by IR, 1H NMR, UV–Vis, cyclic voltammetry and element analysis. The X-ray diffraction analysis displays that the bisthiourea L behaves as sulfur donor to coordinate to Ag and Au atom with μ3-(S, μ2-S′,S′) and μ2-S, S′ coordination mode in 1 and 2, respectively.The designed bisthiourea ligand acts as neutral sulfur donor, while interestingly its silver complex displays a layer structure and gold complex is a molecular compound.Download high-res image (49KB)Download full-size image

•Novel bispyridylpyrrole nitrogen donor ligands are designed and synthesized.•Novel dinuclear silver(I) complexes with substituted bispyridylpyrrole N^N^N ligand are presented.•Complex 1·OTf shows excellent catalytic efficiency and cyclability for A3-coupling reaction under mild conditions.Nitrogen donor ligands HL1, HL3, HL4 and their silver complexes 1·OTf–4·OTf are prepared and fully characterized. Treatment of HL1-HL4 with AgOTf (OTf− = triflato) in presence of base Et3N and co-ligand PPh3 affords dinuclear Ag(I) complexes [Ag2(L)(PPh3)2]·OTf (L = L1−, 1·OTf; L = L2−, 2·OTf; L = L3−, 3·OTf; L = L4−, 4·OTf), respectively. The solid structure displays L acts as bis(bidentate) ligand, bridging between two Ag(I) centres. The Ag⋯Ag interaction as well as other weak interactions, such as Ag⋯Brintermolecular for 1+, Ag⋯Brintramolecular for 2+, Ag⋯S for 3+ are observed. These complexes are applied in the A3-coupling reaction of aldehydes, alkynes and amines under mild conditions, and showed excellent catalytic efficiency and recyclability. 1 mol% catalyst loading gives 99% yield of propargylamines product in 0.15 h at 35 °C in open air atmosphere. 1·OTf can be recycled six times without noticeable less of the catalyst activity.A set of dinuclear silver(I) phosphine complexes containing substituted bispyridylpyrrole N^N^N ligand are prepared and fully characterized. Complex 1·OTf shows excellent catalytic efficiency for A3-coupling reaction under mild conditions, which is one of the most efficient catalysts reported for A3-coupling reaction.Download high-res image (65KB)Download full-size image

We herein report the synthesis and characterization of a series of ruthenium-substituted Keggin-type heteropolytungstates containing {RuII(NO)}, {RuIII(H2O)} or {RuIVCl} species. Although anionic [PW11O39RuII(NO)]4− (1) and [PW11O39RuIII(H2O)]4− (2) are known, a new synthetic method for the preparation of (n-Bu4N)4[1] and (n-Bu4N)4[2] is developed in this paper. Treatment of (n-Bu4N)4[XW11O39(RuN)] with Me3NO afforded the ruthenium(II) nitrosyl complex (n-Bu4N)4[1] in almost quantitative yield. Photolysis of (n-Bu4N)4[1] solution in CH3CN/H2O gives (n-Bu4N)4[2], which is readily oxidized by PhICl2 to yield the RuIV complex (n-Bu4N)4[PW11O39RuIVCl] ((n-Bu4N)4[3]). These complexes are fully characterized by 1H NMR and 31P NMR spectroscopy, infrared spectroscopy, cyclic voltammetry, elemental analysis, thermogravimetric-differential thermal analysis, electrospray ionization mass spectrometry (ESI-MS) and X-ray photoelectron spectroscopy (XPS).

•Six dicopper(I) complexes have synthesized and structurally characterized.•Tri-dentated nitrogen donor PDP− as bridging ligand displays an uncommon coordination mode of μ2-κ2(N,N′), κ2(N′,N″).•The freshly solutions of these complexes in CH2Cl2 display weak 3MLCT luminescence upon excitation at MLCT region.A new class of neutral dicopper(I)–halide complexes with {Cu2(μ-X)} (X = Cl, Br and I) core supported by bispyridylpyrrole ligand have been synthesized and characterized. Replacements of chloride ligand in [Cu2(μ-X)2(PPh3)3] (X = Cl, Br, I) by the anionic PDPH− (PDPH− = 2,5-bis(2′-pyridyl)pyrrole) or PDPBr− (PDPBr− = 2,5-bis(6′-bromo-2′-pyridyl)-pyrrole) ligand gives complexes 1–6. They are [(PDPH)Cu2(μ-X)(PPh3)2] (X = Cl (1); Br (2); I (3)) and [(PDPBr)Cu2(μ-X)(PPh3)2] (X = Cl (4); Br (5); I (6)). The X-ray crystallographic studies reveal these complexes are isostructural. Two phosphine–copper(I) units are linked by one halogen atom and one nitrogen atom from bridging bispyridylpyrrole ligand to form 4-membered Cu2XN core. Each copper atom is located in the center of distorted tetrahedral geometry. The PDPH− and PDPBr− ligands display μ2-κ2(N,N′), κ2(N′,N″) bonding mode. The separation of Cu⋯Cu in 1–6 is in the range of 2.6708(15)–2.7959(6) Å. The photophysical properties of 1–6 are described.Dicopper(I) halide complexes with bispyridylpyrrole ligand, [(PDP)Cu2(μ-X)(PPh3)2], are prepared by treatment of [Cu2(μ-Cl)2(PPh3)3] with deprotonated HPDPH. The freshly solutions of 1–3 in CH2Cl2 display weak 3MLCT luminescence upon excitation at 420 nm in the MLCT region.

A copper-bispyridylpyrrolide complex [Cu(PDPH)Cl] (PDPH = 2,5-bis(2′-pyridyl)pyrrole) was synthesized and characterized. The complex crystallizes in the orthorhombic system with space group Pccn, a = 0.9016(3) nm, b = 1.0931(4) nm, c = 2.5319(8) nm, and V = 2.4951(15) nm3. The copper center is situated in a square planar geometry. The interaction of the copper(II) complex with calf thymus DNA (CT-DNA) was investigated by electronic absorption, circular dichroism (CD) and fluorescence spectra. It is proposed that the complex binds to CT-DNA through groove binding mode. Nuclease activity of the complex was also studied by gel electrophoresis method. The complex can efficiently cleave supercoiled pBR322 DNA in the presence of ascorbate (H2A) via oxidative pathway. The preliminary mechanism of DNA cleavage by the complex with different inhibiting reagents indicates that the hydroxyl radicals were involved as the active species in the DNA cleavage process.

Reaction of deprotonated 2,5-bis(2′-pyridyl)pyrrole (HPDPH) with AgOTf (where OTf− = triflato) in THF readily yields a yellow triangular Ag3 complex [(PDPH)Ag]3 (1), of which the av. Ag⋯Ag distance is 2.902 Å. A mixture of HPDPH and AgOTf reacts with PPh3 to afford a linear Ag3 complex [Ag{(PDPH)Ag(PPh3)}2](OTf) (2·OTf), whereas it reacts with diethyl phosphite in the presence of Li[N(SiMe3)2] to yield a di-nuclear complex Li2[(PDPH)Ag2{P(O)(OEt)2}2](OTf) (Li2·3·OTf). In 2, the terminal Ag atoms are three coordinate containing one phosphorous atom from PPh3 and two nitrogen atoms of the PDPH ligand. The center Ag atom is only two coordinate, binding to the residued pyridyl N atom of the PDPH ligand. In 3, two silver atoms are bridged by one PDPH ligand. Treatment of PDPH with CuCl in the presence of NaH afforded a heterobimetallic copper–sodium complex [Cu(PDPH)2Na(thf)2] (4). The PDPH ligand in 1–4 is nonplanar, with torsion angles between pyridine and pyrrole rings in the range of 15.8–38.3°. The argentophilic interactions, π⋯π stacking, and weak interaction of Ag⋯C(aromatic) are observed in these complexes. Interestingly, treatment of the analogous 2,5-bis(6′-bromo-2′-pyridyl)pyrrole (HPDPBr) with AgOTf affords a di-nuclear complex [(HPDPBr)Ag]2(OTf)2 (5·(OTf)2). Its HPDPBr ligands coordinate to Ag atoms in a head-to-head fashion, and two protonated pyrrole linkages reside in the anti-parallel direction and are non-coordinating. Short Ag⋯Br distances of 3.255–3.390 Å are observed.

Metal nitrido complexes are frequently invoked as key intermediates in numerous synthetic, catalytic and enzymatic transformations, such as C–N and H–N bond-formation, nitrogen atom/group transfer reactions and biological nitrogen fixation by nitrogenase enzyme. Ruthenium nitrido complex is one of the most important metal nitrido complexes. There is a growing interest in chemistry of Ru-nitride. Over the past decade, numerous chemically activated ruthenium nitrido complexes have been discovered. This short review summarizes recent advances in the synthesis and reactivity of these complexes.

Heteropolymetallic complexes [(salen)Ti(ReO4)2] (1) and [{(salen)Ti(ReO4)}2(μ-O)] (2) are easily obtained in high yields via reaction of [(salen)TiCl2] and [{(salen)TiCl2}2(μ-O)] with (Me3SiO)ReO3, respectively (where, salen = (S,S)-N,N′-bis(3,5-di-tert-butylsalicylidene)cyclohexane-1,2-diamine dianion). The structure of complex 2 was established by single-crystal X-ray diffraction. The tetrahedral geometry of the ReO4− anion links the dititanium unit of {(salen)Ti}2(μ-O) in the axial positions. The Re–O–Ti bridge angles range from 146.1(2) to 162.6(2) with a Re⋯Ti separation of 3.780 Å. Complexes 1 and 2 are capable of catalytic oxidation of sulfides with tBuOOH.Graphical abstractHeteropolymetallic complexes [(salen)Ti(ReO4)2] (1) and [{(salen)Ti(ReO4)}2(μ-O)] (2) are easily obtained in high yields. Structural studies of complex 2 indicate Lewis acid TiIV center coordinates ReO4− to form (TiIV–O)–ReVIIO3 species, which include ReO3 fragment as in methyl trioxorhenium (MTO). The resulting TiIV/ReVII complexes are capable of catalytic oxidation of sulfides with tBuOOH.Highlights► Hetero-bimetallic TiIV/ReVII complexes with Re–O–Ti–O–Ti–Re core are synthesized. ► ReO4− anion is activated by coordination with Lewis acidic metal center. ► Coordinated perrhenate groups are capable of catalytic oxidation of sulfides.

We herein report the synthesis and characterization of a series of ruthenium-substituted Keggin-type heteropolytungstates containing {RuII(NO)}, {RuIII(H2O)} or {RuIVCl} species. Although anionic [PW11O39RuII(NO)]4− (1) and [PW11O39RuIII(H2O)]4− (2) are known, a new synthetic method for the preparation of (n-Bu4N)4[1] and (n-Bu4N)4[2] is developed in this paper. Treatment of (n-Bu4N)4[XW11O39(RuN)] with Me3NO afforded the ruthenium(II) nitrosyl complex (n-Bu4N)4[1] in almost quantitative yield. Photolysis of (n-Bu4N)4[1] solution in CH3CN/H2O gives (n-Bu4N)4[2], which is readily oxidized by PhICl2 to yield the RuIV complex (n-Bu4N)4[PW11O39RuIVCl] ((n-Bu4N)4[3]). These complexes are fully characterized by 1H NMR and 31P NMR spectroscopy, infrared spectroscopy, cyclic voltammetry, elemental analysis, thermogravimetric-differential thermal analysis, electrospray ionization mass spectrometry (ESI-MS) and X-ray photoelectron spectroscopy (XPS).

Reaction of deprotonated 2,5-bis(2′-pyridyl)pyrrole (HPDPH) with AgOTf (where OTf− = triflato) in THF readily yields a yellow triangular Ag3 complex [(PDPH)Ag]3 (1), of which the av. Ag⋯Ag distance is 2.902 Å. A mixture of HPDPH and AgOTf reacts with PPh3 to afford a linear Ag3 complex [Ag{(PDPH)Ag(PPh3)}2](OTf) (2·OTf), whereas it reacts with diethyl phosphite in the presence of Li[N(SiMe3)2] to yield a di-nuclear complex Li2[(PDPH)Ag2{P(O)(OEt)2}2](OTf) (Li2·3·OTf). In 2, the terminal Ag atoms are three coordinate containing one phosphorous atom from PPh3 and two nitrogen atoms of the PDPH ligand. The center Ag atom is only two coordinate, binding to the residued pyridyl N atom of the PDPH ligand. In 3, two silver atoms are bridged by one PDPH ligand. Treatment of PDPH with CuCl in the presence of NaH afforded a heterobimetallic copper–sodium complex [Cu(PDPH)2Na(thf)2] (4). The PDPH ligand in 1–4 is nonplanar, with torsion angles between pyridine and pyrrole rings in the range of 15.8–38.3°. The argentophilic interactions, π⋯π stacking, and weak interaction of Ag⋯C(aromatic) are observed in these complexes. Interestingly, treatment of the analogous 2,5-bis(6′-bromo-2′-pyridyl)pyrrole (HPDPBr) with AgOTf affords a di-nuclear complex [(HPDPBr)Ag]2(OTf)2 (5·(OTf)2). Its HPDPBr ligands coordinate to Ag atoms in a head-to-head fashion, and two protonated pyrrole linkages reside in the anti-parallel direction and are non-coordinating. Short Ag⋯Br distances of 3.255–3.390 Å are observed.

Treatment of the 2,5-bis(2′-pyridyl)pyrrolato (PDP−) anion with {Ru(COD)Cl2}n in THF readily yielded [Ru(PDP)(COD)Cl] (1) in almost quantitative yield. Anion metathesis of 1 in organic solvent by NO3− and OTf− (OTf− = triflato) gave [Ru(PDP)(COD)(NO3)] (2) and [Ru(PDP)(COD)(OTf)] (3), and in aqueous solution by BF4− and PF6− afforded aqueous complexes [Ru(PDP)(COD)(H2O)](BF4) (4+·BF4−) and [Ru(PDP)(COD)(H2O)](PF6) (4+·PF6−), respectively. Treatment of 1 with PhICl2 in CH2Cl2 afforded 5 with halogenated pyrrole. These complexes exhibit similar structure, including one Ru(II) atom, one 2,5-bis(2′-pyridyl)pyrrole and one monodentate anion or aqua ligand. Each Ru(II) tightly binds to three adjacent coplanar sites of PDP− ligand to form a meridional configuration. Complex 1 with NaIO4 as the oxidant in EtOAc–CH3CN–H2O (ratio = 3:1:2) proved to be highly effective in the catalytic oxidation of olefins to carbonyl products.