Heteroligand copper(I) complexes of N-thiophosphorylated thioureas and phosphanes: Versatile structures and luminescence

Reaction of the potassium salts of (EtO)₂P(O)CH₂C₆H₄-4-(NHC(S)NHP(S)(OiPr)₂) (HL^I), (CH₂NHC(S)NHP(S)(OiPr)₂)₂ (H₂L^II) or cyclam(C(S)NHP(S)(OiPr)₂)₄ (H₄L^III) with [Cu(PPh₃)₃I] or a mixture of CuI and Ph₂P(CH₂)_1-3PPh₂ or Ph₂P(C₅H₄FeC₅H₄)PPh₂ in aqueous EtOH/CH₂Cl₂ leads to [Cu(PPh₃)L^I] (1), [Cu₂(Ph₂PCH₂PPh₂)₂L^II] (2), [Cu{Ph₂P(CH₂)₂PPh₂}L^I] (3), [Cu{Ph₂P(CH₂)₃PPh₂}L^I] (4), [Cu{Ph₂P(C₅H₄FeC₅H₄)PPh₂}L^I] (5), [Cu₂(PPh₃)₂L^II] (6), [Cu₂(Ph₂PCH₂PPh₂)L^II] (7), [Cu₂{Ph₂P(CH₂)₂PPh₂}₂L^II] (8), [Cu₂{Ph₂P(CH₂)₃PPh₂}₂L^II] (9), [Cu₂{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₂L^II] (10), [Cu₈(Ph₂PCH₂PPh₂)₈L^IIII₄] (11), [Cu₄{Ph₂P(CH₂)₂PPh₂}₄L^III] (12), [Cu₄{Ph₂P(CH₂)₃PPh₂}₄L^III] (13) or [Cu₄{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₄L^III] (14) complexes. The structures of these compounds were investigated by IR, ¹H, ³¹P{¹H} NMR spectroscopy; their compositions were examined by microanalysis. The luminescent properties of the complexes 1-14 in the solid state are reported.     

Pd(II) complexes containing N-alkyl-3-pyridine-5-trifluoromethyl pyrazole ligands: Synthesis, NMR studies and X-ray crystal structures

Palladium [PdCl₂(L)] complexes with N-alkylpyridylpyrazole derived ligands [2-(5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L¹), 2-(1-ethyl-5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L²), 2-(1-octyl-5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L³), and 2-(3-pyridin-2-yl-5-trifluoromethyl-pyrazol-1-yl)ethanol (L⁴) were synthesised. The crystal and molecular structures of [PdCl₂(L)] (L = L², L³, L⁴) were resolved by X-ray diffraction, and consist of monomeric cis-[PdCl₂(L)] molecules. The palladium centre has a typical square-planar geometry, with a slight tetrahedral distortion. The tetra-coordinate metal atom is bonded to one pyridinic nitrogen, one pyrazolic nitrogen and two chlorine ligands in cis disposition. Reaction of L (L², L⁴) with [Pd(CH₃CN)₄](BF₄)₂, in the ratio 1M:2L, gave complexes [Pd(L)]₂(BF₄)₂. Treatment of [PdCl₂(L)] (L = L², L⁴) with NaBF₄ and pyridine (py) and treatment of the same complexes with AgBF₄ and triphenylphosphine (PPh₃) yielded [Pd(L)(py)₂](BF₄)₂ and [Pd(L)(PPh₃)₂](BF₄)₂ complexes, respectively. Finally, reaction of [PdCl₂(L⁴)] with 1 equiv of AgBF₄ yields [PdCl(L⁴)](BF₄).     

Diether functionalized rhodium(I)-N-heterocyclic carbene complexes and their catalytic application for transfer hydrogenation reactions

N-heterocyclic carbene (NHC) complexes of rhodium(I) (3 and 4) bearing one diether (MeOCH₂CH₂OCH₂CH₂-NHC) functionality on N¹ and bulky benzyl groups (CH₂-C₆H₂(CH₃)₃-2,4,6 and CH₂-C₆(CH₃)₅) on N³ of (5,6-dimethyl)benzimidazole were synthesized by deprotonation of the corresponding benzimidazolium salt with [Rh(μ-OMe)(1,5-cod)]₂ in dichloromethane at ambient temperature. All compounds have been fully characterized by elemental analysis, ¹H and ¹³C NMR spectroscopy. X-ray diffraction studies on single crystals of 3a and 3b confirm the cis square planar geometry. All of the new benzimidazol-2-ylidene rhodium(I) complexes were found to be effective catalysts for the transfer hydrogenation reaction.     

Syntheses, structures and bioactivities of silver(I) complexes with dithioether ligands that contain a di- or triethylene glycol chain and different terminal groups

A series of flexible dithioethyl ligands that contain ethyleneoxy segments were designed and synthesized, including bis(2-(pyridin-2-ylthio)ethyl)ether (L¹), 1,2-bis(2-(pyridin-2-ylthio)ethoxy)ethane (L²), bis(2-(benzothiazol-2-ylthio)ethyl)ether (L³) and 1,2-bis(2-(benzothiazol-2-ylthio)ethoxy)ethane (L⁴). Reactions of these ligands with AgNO₃ led to the formation of four new supramolecular coordination complexes, [Ag₂L¹(NO₃)₂]₂ (1), [Ag₂L²(NO₃)₂] (2), [AgL³(NO₃)]_∞ (3) and [AgL⁴(NO₃)] (4) in which the length of the (CH₂CH₂O)_n spacers and the terminal groups of ligands cause subtle geometrical differences. Studies of the inhibitory effect to the growth of Phaeodactylum tricornutum show that all four complexes are active and the compound 4 has the highest inhibitory activity.     

Synthesis, spectroscopic properties and structural characterisation of Pd(II) and Pt(II) complexes with 1,3,5-pyrazole derived ligands. Rotation around the metal-N bond

Reactions of ligands 1-ethyl-5-methyl-3-phenyl-1H-pyrazole (L¹) and 5-methyl-1-octyl-3-phenyl-1H-pyrazole (L²) with [PdCl₂(CH₃CN)₂ and K₂PtCl₄ gave complexes trans-[MCl₂(L)₂] (L = L¹, L²). The new complexes were characterised by elemental analyses, conductivity measurements, infrared, ¹H and ¹³C{¹H} NMR spectroscopies and X-ray diffraction. The NMR study of the complex [PdCl₂(L¹)₂], in CDCl₃ solution, is consistent with a very slow rotation of ligands around the Pd-N bond, so that two conformational isomers can be observed in solution (syn and anti). Different behaviour is observed for complexes [PdCl₂(L²)₂] and [PtCl₂(L)₂] (L = L¹, L²), which present an isomer in solution at room temperature (anti). The crystal structure of [PdCl₂(L¹)₂] complex is described, where the Pd(II) presents a square planar geometry with the ligands coordinated in a trans disposition.     

The syntheses, characterizations, X-ray crystal structures and properties of Cu(I) complexes of a bis-bidentate schiff base ligand

Bis-bidentate Schiff base ligand L and its two mononuclear complexes [CuL(CH₃CN)₂]ClO₄ (1) and [CuL(PPh₃)₂]ClO₄ (2) have been prepared and thoroughly characterized by elemental analyses, IR, UV-Vis, NMR spectroscopy and X-ray diffraction analysis. In both the complexes the metal ion auxiliaries adopt tetrahedral coordination environment. Their reactivity, electrochemical and photophysical behavior have been studied. Complex 1 shows reversible Cu^II/I couple with potential 0.74 V versus Ag/AgCl in CH₂Cl₂. At room temperature L is weakly fluorescent in CH₂Cl₂, however in Cu(I) complexes 1 and 2 the emission in quenched.     

Zinc(II) and mercury(II) coordination architectures with two pyridyl/benzimidazol-1-yl-based ligands: Crystal structures and photoluminescent properties

In our efforts to investigate the relationships between the structures of ligands and their complexes, two structurally related ligands, 1-(2-pyridylmethyl)-1H-benzimidazole (L¹) and 1-(4-pyridylmethyl)-1H-benzimidazole (L²), and their four complexes, [Zn(L¹)₂Cl₂] (1), [Hg(L¹)Br₂]_∞ (2), {[Zn(L²)Cl₂](CH₃CN)}_∞ (3) and [Hg(L²)Br₂]₂(CH₃CN)₂ (4) were synthesized and structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction analysis. Structural analyses show that 1 has a mononuclear structure, and 2 and 3 both take 1D structure. While 4 takes a dinuclear structure. 1, 2 and 4 were further linked into higher-dimensional supramolecular networks by weak interactions, such as C-H?Cl and C-H?Br H-bonding, C-H?π, and π?π stacking interactions. The structural differences of 1-4 may be attributed to the difference of the spatial positions of the terminal N donor atoms in the pendant pyridyl groups in L¹ and L², in which the pyridine rings may act as the directing group for coordination and the benzimidazole rings act as the directing group for π?π stacking and C-H?π interactions. The luminescent properties of the corresponding complexes and ligands have been further investigated.     

Synthesis and properties of new trinuclear Mo(II) complexes containing imidazole and benzimidazole ferrocene units

The reaction of FcCOCl (Fc = (C₅H₅)Fe(C₅H₄)) with benzimidazole or imidazole in 1:1 ratio gives the ferrocenyl derivatives FcCO(benzim) (L1) or FcCO(im) (L2), respectively. Two molecules of L1 or L2 can replace two nitrile ligands in [Mo(η³-C₃H₅)(CO)₂(CH₃CN)₂Br] or [Mo(η³- C₅H₅O)(CO)₂(CH₃CN)₂Br] leading to the new trinuclear complexes [Mo(η³-C₃H₅)(CO)₂(L)₂Br] (C1 for L = L1; C3 for L = L2) and [Mo(η³-C₅H₅O)(CO)₂(L)₂Br] (C2 for L = L1; C4 for L = L2) with L1 and L2 acting as N-monodentade ligands. L1, L2 and C2 were characterized by X-ray diffraction studies. [Mo(η³-C₅H₅O)(CO)₂(L1)₂Br] was shown to be a trinuclear species, with the two L1 molecules occupying one equatorial and one axial position in the coordination sphere of Mo(II). Cyclic voltammetric studies were performed for the two ligands L1 and L2, as well as for their molybdenum complexes, and kinetic and thermodynamic data for the corresponding redox processes obtained. In agreement with the nature of the frontier orbitals obtained from DFT calculations, L1 and L2 exhibit one oxidation process at the Fe(II) center, while C1, C3, and C4 display another oxidation wave at lower potentials, associated with the oxidation of Mo(II).     

Cyclodiphosphazane appended with thioether functionality: Synthesis, transition metal chemistry and catalytic application in Suzuki-Miyaura cross-coupling reactions

The coordination chemistry of thioether functionalized cyclodiphosphazane ligand, cis-{^tBuNP(OCH₂CH₂SCH₃)}₂ (1) is described. The reactions of 1 with [Pd (COD)Cl₂] in 1:1, 1:2 and 2:1 M ratios afforded cis-[PdCl₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (2), cis-[{PdCl₂}₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (3) and trans-[PdCl₂{(^tBuNP(OCH₂CH₂SCH₃))₂}₂] (4), respectively. Treatment of 1 with [Pd(PEt₃)Cl₂]₂ or [PdCl(η³-C₃H₅)]₂ in appropriate molar ratios produce the mono- and binuclear complexes [PdCl₂(PEt₃{^tBuNP(OCH₂CH₂SCH₃)}₂] (5) and [{PdCl(η³-C₃H₅)}₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (6) in good yield. The reaction of 1 with [{Ru(p-cymene)Cl₂}₂] afforded the mononuclear cationic complex, [{(p-cymene)RuCl{^tBuNP(OCH₂CH₂SCH₃)}₂]Cl (7), whereas the reactions of [Rh(COD)Cl]₂, [Pt(COD)Cl₂] and [Au(SMe₂)Cl] with 1 yielded the corresponding P-coordinated neutral complexes, [RhCl(COD){^tBuNP(OCH₂CH₂SCH₃)}₂] (8)cis-[PtCl₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (9), respectively. The binuclear palladium(II) complex 3 was found to be an effective catalyst for the Suzuki-Miyaura cross-coupling reactions.     

Bis(O2S2 macrocycle) complexes of palladium(II)

Two isomeric dibenzo-O₂S₂ macrocycles L¹ and L² have been synthesised and their coordination chemistry towards palladium(II) has been investigated. Two-step approaches via reactions of 1:1-type complexes, [cis-Cl₂LPd] (1a: L = L¹, 1b: L = L²), with different O₂S₂ macrocycle systems (L¹ and L²) have led to the isolation of the following bis(O₂S₂ macrocycle) palladium(II) complexes in the solid state: [Pd(L¹)₂](ClO₄)₂ (2a) and a mixture of [Pd(L¹)₂](ClO₄)₂ (2a) + [Pd(L²)₂](ClO₄)₂ (2b).     

One-pot syntheses of alkenyl-phosphonio complexes of ruthenium(II), rhodium(III) and iridium(III) bearing p-cymene or pentamethylcyclopentadienyl groups

Reaction of [(p-cymene)RuCl₂(PPh₃)] (1) or [Cp^∗MCl₂(PPh₃)] (Cp^∗ = C₅Me₅) (3a: M = Rh; 4a: M = Ir) with 1-alkynes and PPh₃ were carried out in the presence of KPF₆, generating the corresponding alkenyl-phosphonio complexes, [(p-cymene)RuCl(PPh₃){CHCR(PPh₃)}](PF₆) (2a: R = Ph; 2b: R = p-tolyl) or [Cp^∗MCl(PPh₃){CHCPh(PPh₃)}](PF₆) (5: M = Rh; 6: M = Ir). Similar reactions of complexes [Cp^∗RhCl₂(L¹)] (3a: L¹ = PPh₃; 3c: L¹ = P(OMe)₃) with L² (L² = PPh₃, PMePh₂, P(OMe)₃) gave [Cp^∗RhCl(L¹)(L²)](PF₆) (7bb: L¹ = L² = PMePh₂; 7ca: L¹ = P(OMe)₃, L² = PPh₃; 7cc: L¹ = L² = P(OMe)₃). Alkenyl-phosphonio complex 5 was treated with P(OMe)₃ or 2,6-xylyl isocyanide, affording [Cp^∗RhCl(L){CHCPh(PPh₃)}](PF₆) (8a: L = P(OMe)₃; 8b: L = 2,6-xylNC). X-ray structural analyses of 2a, 6 and 8a revealed that the phosphonium moiety bonded to the C_β atom of the alkenyl group are E configuration.     

Interactions of arene-Ru(II)-chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin

The interactions of π-arene-Ru(II)-chloroquine complexes with human serum albumin (HSA), apotransferrin and holotransferrin have been studied by circular dichroism (CD) and UV-Visible spectroscopies, together with isothermal titration calorimetry (ITC). The data for [Ru(η⁶-p-cymene)(CQ)(H₂O)Cl]PF₆ (1), [Ru(η⁶-benzene)(CQ)(H₂O)Cl]PF₆ (2), [Ru(η⁶-p-cymene)(CQ)(H₂O)₂][PF₆]₂ (3), [Ru(η⁶-p-cymene)(CQ)(en)][PF₆]₂ (4), [Ru(η⁶-p-cymene)(η⁶-CQDP)][BF₄]₂ (5) (CQ: chloroquine; DP: diphosphate; en: ethylenediamine), in comparison with CQDP and [Ru(η⁶-p-cymene)(en)Cl][PF₆] (6) as controls demonstrate that 1, 2, 3, and 5, which contain exchangeable ligands, bind to HSA and to apotransferrin in a covalent manner. The interaction did not affect the α-helical content in apotransferrin but resulted in a loss of this type of structure in HSA. The binding was reversed in both cases by a decrease in pH and in the case of the Ru-HSA adducts, also by addition of chelating agents. A weaker interaction between complexes 4 and 6 and HSA was measured by ITC but was not detectable spectroscopically. No interactions were observed for complexes 4 and 6 with apotransferrin or for CQDP with either protein. The combined results suggest that the arene-Ru(II)-chloroquine complexes, known to be active against resistant malaria and several lines of cancer cells, also display a good transport behavior that makes them good candidates for drug development.     

Rhenium(III) and technetium(III) complexes with 2-mercapto-1,3-azole ligands and X-ray crystal structures

Reactions of labile [MCl₃(PPh₃)₂(NCMe)] (M = Tc, Re) precursors with 1H-benzoimidazole-2-thiol (H₂L¹), 5-methyl-1H-benzoimidazole-2-thiol (H₂L²) and 1H-imidazole-2-thiol (H₂L³), in the presence of PPh₃ and [AsPh₄]Cl gave a new series of trigonal bipyramidal M(III) complexes [AsPh₄]{[M(PPh₃)Cl(H₂L^1-3)₃]Cl₃} (M = Re, 1-3; M = Tc, 4-6). The molecular structures of 1 and 3 were determined by X-ray diffraction. When the reactions were carried out with benzothiazole-2-thiol (HL⁴) and benzoxazole-2-thiol (HL⁵), neutral paramagnetic monosubstituted M(III) complexes [M(PPh₃)₂Cl₂(L^4,5)] (M = Re, 8, 9; M = Tc, 10, 11) were obtained. In these compounds, the central metal ions adopt an octahedral coordination geometry as authenticated by single crystal X-ray diffraction analysis of 8 and 11. Rhenium and technetium complexes 1, 4 and rhenium chelate compounds 8, 9 have been also synthesized by reduction of [MO₄]⁻ with PPh₃ and HCl in the presence of the appropriate ligand. All the complexes were characterized by elemental analyses, FTIR and NMR spectroscopy.     

Structures and luminescence of mononuclear and dinuclear base-stabilized gold(I) pyrazolate complexes

The mono- and dinuclear base-stabilized gold(I) pyrazolate complexes, (PPh₃)Au(μ-3,5-Ph₂pz)) (1), (TPA)Au(3,5-Ph₂pz), TPA=1,3,5-triaza-7-phophaadamantane (2), [(PPh₃)₂Au(μ-3,5-Ph₂pz)]NO₃ (3) and [(dppp)Au(μ-3,5-Ph₂pz)]NO₃, dppp=bis(diphenylphosphino)propane (4), have been synthesized and structurally characterized. The mononuclear gold(I) complexes 1 and 2 show intermolecular Au?Au interactions of 3.1540(6) and 3.092(6) Å, while the dinuclear gold(I) complexes 3 and 4 show an intramolecular Au?Au distances of 3.3519(7) and 3.109(2) Å, respectively, typical of an aurophilic attraction. Complexes 1-4 exhibit luminescence at 77 K when excited with ca. 333 nm UV light with an emission maximum at ca. 454 nm. The emission has been assigned to ligand-to-metal charge transfer, LMCT, based upon the vibronic structure that is observed.     

Homoleptic palladium complexes with phosphine-amide or iminophosphine ligands

The reaction between Pd(dba)₂ and phosphino-amide ligands yielded the unexpected Pd(II) homoleptic complexes [Pd(o-Ph₂PC₆H₄CO-NR)₂] [R = ⁱPr (1), Ph (2), 4-MeC₆H₄ (3), 4-FC₆H₄ (4)], in which an κ²-P,N coordination mode for diphenylphosphine-benzamidate ligands is observed. In order to induce amide protonation in the ligands and subsequent κ²-P,O coordination, compounds (1-4) were treated with HClO₄(aq) to give cationic complexes [Pd(o-Ph₂PC₆H₄CO-NHR)₂][ClO₄]₂ (5-8). These complexes and the analogous with iminophosphine ligands [Pd(o-Ph₂PC₆H₄CHN-R)₂] [ClO₄]₂ [R = ⁱPr (9), Ph (10)] can be alternatively obtained when [PdCl₂(PhCN)₂] is treated with AgClO₄ in the presence of the corresponding ligand. The reaction of Pd(dba)₂ with iminophosphines has also been explored, yielding in this case the Pd(0) derivatives [Pd(o-Ph₂PC₆H₄CHN-R)₂] [R = ⁱPr (11), Ph (12)]. X-ray structures of (3), (4), (5), (8) and (9) have been established, allowing an interesting comparative structural discussion.     

Rhodium and iridium complexes bearing an alkyloxazoline-substituted indenyl ligand (Indox ligand) and their stereoselective construction of metal-centered chirality

The Indox ligands, [{(S)-(ⁱPr)Indox}_n]H (1) [n=2 (a), 3 (b)] and [{(H)Indox}_n=3]H (2), in which an indenyl group and an oxazoline ring are connected by an ethylene or propylene spacer, have been prepared. Reaction of [Ir(coe)₂Cl]₂ or [RhCl(C₂H₄)₂]₂ with the potassium salt of 1 afforded η⁵-[{(S)-(ⁱPr)Indox}_n]Ir(coe)₂ (3) or η⁵-[{(S)-(ⁱPr)Indox}_n]Rh(C₂H₄)₂ (6) as a 1:1 mixture of two diastereomers. The oxazoline ring in 3 and 6 did not coordinate to the metal center. When the complexes 3 or 6 reacted with iodine in diethyl ether, oxidative addition proceeded and the oxazoline ring coordinated to the metal center to give diiodoiridium(III) or rhodium(III) complexes, η⁵:η¹-[{(S)-(ⁱPr)Indox}_n]M(I)₂ [M=Ir (4), Rh (7)]. The corresponding diiodoiridium(III) complex bearing the Indox ligand 2, η⁵:η¹-[{(H)Indox}_n=2]Ir(I)₂ (5), was also prepared by a similar method. Reaction of 4 or 7 with PPh₃ in THF afforded diiodo-phosphine complexes, η⁵-[{(S)-(ⁱPr)Indox}_n]M(PPh₃)(I)₂ [M=Ir (8), Rh (9)] as a 1:1 mixture of two diastereomers in which the oxazoline ring dissociated from the metal center. The related reaction of 8 or 9 with more than 2 equiv. of AgOTf afforded the cationic complexes, [η⁵:η¹-[{(S)-(ⁱPr)Indox}_n]M(PPh₃)(OTf)]OTf [M=Ir (10), Rh (11)], having a stereogenic center at the metal center as a mixture of only two diastereomers. From ¹H and ³¹P NMR analyses, each diastereomer of 8 or 9 afforded only a single isomer of 10 or 11. The corresponding iridium(III) complex bearing the Indox ligand 2, [η⁵:η¹-[{(H)Indox}_n=3]Ir(PPh₃)(OTf)]OTf (12) was also prepared. The coordinated triflate ligand of 12 was slowly replaced by water in CDCl₃ to afford the dicationic aquo complex, (S^*_pl,R^*_Ir)-[η⁵:η¹-[{(H)Indox}_n=3]Ir(PPh₃)(H₂O)](OTf)₂ (13). The monocationic complex, [η⁵:η¹-[{(S)-(ⁱPr)Indox}_n=2]Ir(PPh₃)(I)]OTf (14a), having metal-centered chirality, was observed as a mixture of only two diastereomers in the reaction of 10a (a mixture of two diastereomers) with 1 equiv. of AgOTf. These observations indicated that the ligand exchange reaction of 8 or 9 with AgOTf contained the following three steps: (i) abstraction of one of the two prochiral iododes by AgOTf, (ii) recoordination of the oxazoline ring, and (iii) exchange of the remaining iodide for the triflate by AgOTf. The stereochemistry around the metal center was determined at the second step. All complexes have been characterized by usual spectroscopic methods as well as elemental analyses, and 4 and 13 have been characterized by X-ray analyses.     

Synthesis, characterization, crystal structures and photophysical properties of copper(I) complexes containing 1,1′-bis(diphenylphosphino)ferrocene (B-dppf) in doubly-bridged mode

Five copper(I) complexes having general formula [Cu₂(μ-X)₂(κ²-P,P-B-dppf)₂] (X = Cl(1), Br(2), I(3), CN(4), and SCN(5)) were prepared starting with CuX and B-dppf in 1:1 molar ratio in DCM-MeOH (50:50 V/V) at room temperature. The complexes have been characterized by elemental analyses, IR, ¹H NMR, ³¹P NMR and electronic spectral studies. Molecular structures for 1, 2 and 4 were determined crystallographically. Complexes 1, 2 and 4 exist as centrosymmetric dimers in which the two copper atoms are bonded to two bridging B-dppf ligands and two bridging (pseudo-)halide groups in a μ-η¹ bonding mode to generate nearly planar Cu₂(μ-η¹-X)₂ framework. Both bridging B-dppf ligands are arranged in antiperiplanar staggered conformation in 1 and 2 (mean value 56.40-56.76°), and twisted from the eclipsed conformation (mean value 78.19°) in 4. The Φ angle value in 4 is relatively larger as compared to 1 and 2. This seems to indicate that the molecular core [Cu₂(μ-η¹-X)₂] in 4 is a sterically demanding system that forces the B-dppf ligand to adopt a relatively strained conformation in comparison to less strained system in 1 and 2. All the complexes exhibit moderately strong luminescence properties in the solution state at ambient temperature.     

Reactions of 2-(arylazo)aniline with iridium trichloride: Synthesis, characterization and structure of new cyclometallated complexes of iridium(III)

Reactions of 2-(arylazo)aniline, HL (H represents the dissociable protons upon orthometallation and HL is p-RC₆H₄NNC₆H₄-NH₂; RH for HL¹; CH₃ for HL² and Cl for HL³) with IrCl₃ in methanol afforded orthometallated complexes of composition (L)(HL)IrCl₂ (2) and (L)(MeOH)IrCl₂ (3), respectively. Complex (L)(MeOH)IrCl₂ (3) converted into (L)(CH₃CN)IrCl₂ (4) upon refluxing in acetonitrile. The X-ray structure of the complexes (L¹)(HL¹)IrCl₂ (2a) and (L³)(CH₃CN)IrCl₂ (4c) have been determined and characterized unequivocally. The anionic L⁻ binds the metal in tridentate (C, N, N) manner for all the complexes.     

Chiral 2-pyridyl alcoholate copper complexes: crystal structures of [bis(2-pyridyl alcoholate)copper(II)] and the use of [(2-pyridyl alcoholate)copper(II)]and [(2-pyridyl alcoholate)copper(I)] in asymmetric cyclopropanation of styene and allylic oxidation of cyclohexene

Chiral N,O pyridine alcohols HL¹-HL⁶ were used to form complexes with copper(II) ions. Ligands HL¹ and HL² formed complexes with copper(II) ions when Cu(OAc)₂ and HL were refluxed in methanol/ethanol mixture. Ligand HL³ formed a complex with copper(II) when deprotonated with NaH and stirred in a Cu(II) acetate THF solution. Ligands HL⁴-HL⁶ did not form complexes with copper(II) under similar conditions. Two complexes, [Cu(L¹)₂] and [Cu(L²)₂], were isolated as single crystals and characterized by X-ray crystallography. These complexes showed low catalytic activities in asymmetric reactions. However, they became active when reacted with triflic acid. Copper complexes, [Cu(L)] or [Cu(L)]⁺, formed in situ by reacting ligands HL with copper(I) or (II) ions, respectively, were also found to be active copper catalysts for asymmetric cyclopropanation of styrene with ethyl diazoacetate and allylic oxidation of cyclohexene with t-butylperoxybenzoate. Enantioselectivities up to 56% and 38% were obtained in asymmetric cyclopropanation of styrene and asymmetric allylic oxidation of cyclohexene, respectively.     

Syntheses, structures, thermal behavior and solution studies of two types of Hg(II) complexes with [1,3-di(2-methoxy)benzene]triazene

The reaction of [1,3-di(2-methoxy)benzene]triazene, [HL], with Hg(CH₃COO)₂ and Hg(SCN)₂ in methanol as solvent, resulted in the formation of [HgL₂] (1) and [HgL(SCN)] (2), respectively. These compounds were characterized by means of X-ray diffraction, FT-IR spectroscopy, CHN and TGA-DTA analysis. In the lattice of the compound 1, the mono-nuclear complexes were connected to dimer structure by intermolecular non-classical C-H···O hydrogen bonds. Also, weak Hg-η²-arene π-interactions link the dimers into 1D supramolecular chains. The compound 2 is a 2D coordination polymer induced by C-H···π stacking interactions between 1D chains produced by weak Hg-η³-η³-arene π-interactions. The results of studies of the stoichiometry and formation of complexes of 1 and 2 in methanol solution were found to be in support of their solid state stoichiometry.