Preparation,Structural Characterization,and Antifungal Activities of Complexes of Group 12 Metals with 2‐Acetylpyridine‐ and 2‐Acetylpyridine‐N‐oxide‐4N‐phenylthiosemicarbazones

Reaction of group 12 metal dihalides in ethanolic media with 2‐acetylpyridine ⁴N‐phenylthiosemicarbazone ( H4PL ) and 2‐acetylpyridine‐N‐oxide ⁴N‐phenylthiosemicarbazone ( H4PLO ) afforded the compounds [M(H4PL)X₂] (X = Cl, Br, M = Zn, Cd, Hg; X = I, M = Zn, Cd) ( 1–8 ), [Hg(4PL)I]₂ ( 9 ) and [M(H4PLO)X₂] (X = Cl, Br, I, M = Zn, Cd, Hg) ( 10–18 ). H4PL , H4PLO and their complexes were characterized by elemental analysis and by IR and ¹H and ¹³C NMR spectroscopy (and the cadmium complexes by ¹¹³Cd NMR spectroscopy), and H4PL , H4PLO , ( 5 · DMSO) and ( 9 ) were additionally studied by X‐ray diffraction. H4PL is N,N,S‐tridentate in all its complexes, including 9 , in which it is deprotonated, and H4PLO is in all cases O,N,S‐tridentate. In all the complexes, the metal atoms are pentacoordinate and the coordination polyhedra are redistorted tetragonal pyramids. In assays of antifungal activity against Aspergillus niger and Paecilomyces variotii, the only compound to show any activity was [Hg(H4PLO)I₂] ( 18 ).     

Synthesis and Structural Characterization of Metal Complexes of 2‐Formylpyrrole‐4N‐ethylthiosemicarbazone (4 EL1) and 2‐Acetylpyrrole‐4N‐ethylthiosemicarbazone (4 EL2)

The reactions of ⁴N‐ethyl‐2‐[1‐(pyrrol‐2‐yl)methylidene(hydrazine carbothioamide ( 4 EL₁ ) and ⁴N‐ethyl‐2[1‐(pyrrol‐2‐yl)ethylidene(hydrazine carbothioamide ( 4 EL₂ ) with Group 12 metal halides afforded complexes of types [M(L)₂X₂] (M = Zn, Cd; L = 4 EL₁, 4 EL₂; X = Cl, Br, I; 1 – 6 , 14 – 19 ) and [M(L)X₂] (M = Hg; L = 4 EL₁, 4 EL₂; X = Cl, Br, I; 7 – 9 , 20 – 22 ). In addition, reaction of 4 EL₁ with salts of Cu^II, Ni^II, Pd^II and Pt^II afforded compounds of type [M(4 EL₁–H)₂] ( 10 – 13 ). The new compounds were characterized by elemental analysis, FAB mass spectrometry, IR and electronic spectroscopy and, for sufficiently soluble compounds, ¹H, ¹³C and, when appropriate, ¹¹³Cd or ¹⁹⁹Hg NMR spectrometry. The spectral data suggest that in their complexes with Group 12 metal cations, both thiosemicarbazones are neutral and S‐monodentate; and for [Zn(4 EL₁)₂I₂] ( 3 ), [Cd(4 EL₁)₂Br₂] ( 5 ) and [Hg(4 EL₁)Cl₂]₂ ( 7 ) this was confirmed by X‐ray diffractometry. By contrast, in its complexes with Cu^II and Group 10 metal cations, 4 EL₁ is monodeprotonated and S,N‐bidentate, as was confirmed by X‐ray diffractometry for [Ni(4 EL₁–H)₂] ( 11 ) and [Pd(4 EL₁–H)₂] ( 12 ).     

A Mixed‐Valence Tri‐Zinc Complex, [LZnZnZnL] (L=Bulky Amide), Bearing a Linear Chain of Two‐Coordinate Zinc Atoms

Reduction of a variety of extremely bulky amido Group 12 metal halide complexes, [LMX(THF)_0,1] (L=amide; M=Zn, Cd, or Hg; X=halide) with a magnesium(I) dimer gave a homologous series of two‐coordinate metal(I) dimers, [L′MML′] (L′=N(Ar^?)(SiMe₃), Ar^?=C₆H₂{C(H)Ph₂}₂Prⁱ‐2,6,4); and the formally zinc(0) complex, [L*ZnMg(^MesNacnac)] (L*=N(Ar*)(SiPrⁱ₃); Ar*=C₆H₂{C(H)Ph₂}₂Me‐2,6,4; ^MesNacnac=[(MesNCMe)₂CH]^?, Mes=mesityl), which contains the first unsupported Zn? Mg bond. Two equivalents of [L*ZnMg(^MesNacnac)] react with ZnBr₂ or ZnBr₂(tmeda) to give the mixed valence, two‐coordinate, linear tri‐zinc complex, [L*Zn^IZn⁰Zn^IL*], and the first zinc(I) halide complex, [L*ZnZnBr(tmeda)], respectively. The analogues [L*ZnMZnL*] (M=Cd or Hg), were also prepared, the Cd species contains the first Zn? Cd bond in a molecular compound. Metal–metal bonding was studied by DFT calculations.     

{Au(IPr)}2(μ-OH)]X complexes: synthetic, structural and catalytic studies

The synthesis of a series of dinuclear gold hydroxide complexes has been achieved. These complexes of type [{Au(IPr)}₂(μ‐OH)]X (X=BF₄, NTf₂, OTf, FABA, SbF₆; IPr=2,6‐bis(disopropylphenyl)imidazol‐2‐ylidene; NTf₂=bis(trifluoromethanesulfonyl)imidate; OTf=trifluoromethanesulfonate; FABA=tetrakis(pentafluorophenyl)borate) are easily formed in the presence of water and prove highly efficient in the catalytic hydration of nitriles. Their facile formation in aqueous media suggests they are of relevance in gold‐catalyzed reactions involving water. Additionally, a series of [Au(IPr)(NCR)][BF₄] (R=alkyl, aryl) complexes was synthesized as they possibly occur as intermediates in the catalytic reaction mechanism. ¹H and ¹³C NMR data as well as key bond lengths obtained by X‐ray diffraction studies are compared and reveal an interesting structure–activity relationship. The collected data indicate a negligible effect of the nature of the nitrile on the reactivity of [Au(L)(NCR)][X] complexes in catalysis.     

Coordination of ZnII,CdII, and HgII by 2‐Pyridineformamide‐3‐piperidyl‐thiosemicarbazone

Sodium in dry methanol reduces 2‐cyanopyridine in the presence of 3‐piperidylthiosemicarbazide and produces 2‐pyridine‐formamide‐3‐piperidylthiosemicarbazone, HAmpip. Complexes with zinc(II), cadmium(II), and mercury(II) have been prepared and characterized by elemental analyses and spectroscopic techniques. In addition, the crystal structures of [Zn(Ampip)₂], [Zn(Ampip)(Oac)]₂, [Cd(HAmpip)Cl₂]·(CH₃)₂SO, [Cd(HAm‐pip)Br₂] · (CH₃)₂SO, [Cd(HAmpip)I₂]·(CH₃)₂SO, [Cd(Ampip)₂] and [Hg(HAmpip)Br₂]·(CH₃)₂SO have been solved. Coordination of the anionic and neutral thiosemicarbazone ligand is via the pyridyl nitrogen, imine nitrogen and thiolato/thione sulfur atom, respectively. In [Zn(Ampip)(OAc)]₂ one of the bridging acetato ligands has monodentate coordination and the other bridges in a bidentate manner. ¹¹³Cd NMR studies were carried out on the [Cd(HAmpip)X₂](X = Cl, Br or I) and [Cd(Ampip)(OAc)]₂ complexes. The ¹¹³Cd chemical shifts are affected by the halogen and range from 411 to 301 ppm, and the spectrum of [Cd(Ampip)(OAc)]₂ shows two signals at 450 and 251 ppm. The ¹⁹⁹Hg NMR spectrum of [Hg(HAmpip)Cl₂] also is discussed.     

Preparation of Hydride‐Ethylene Complexes of Osmium

Ethylene complexes [OsH(η²‐CH₂=CH₂)L₄]Y ( 1 , 2 ) [L = PPh(OEt)₂, P(OEt)₃; Y = OTf, BPh₄] were prepared by reacting the dihydride OsH₂L₄ first with methyl triflate CH₃OTf and then with ethylene (1 atm). Alternatively, the compound [OsH(η²‐CH₂=CH₂){PPh(OEt)₂}₄]OTf was prepared by allowing the dinitrogen derivative [OsH(N₂){PPh(OEt)₂}₄]OTf to react with ethylene. Acrylonitrile CH₂=C(H)CN reacts with OsH(OTf)L₄ [L = P(OEt)₃] to give the complex [OsH{κ¹‐NCC(H)=CH₂}{P(OEt)₃}₄]BPh₄ ( 3 ). The complexes were characterized spectroscopically (IR and ¹H, ¹³C, ³¹P NMR) and by X‐ray crystal structure determination of the [OsH(η²‐CH₂=CH₂){PPh(OEt)₂}₄]BPh₄ derivative.     

Gold(I) ‐Nickel(II)‐4,4′‐bpy‐Phosphine Complexes: Synthesis and Multinuclear NMR Study

Silver triflate [AgOTf] assisted de‐bromination gives [Ni(dppm/dppe/(PPh₃)₂) (OTf)₂], which on reaction with 4,4′‐bpy and gold(I) phosphines in dichloromethane medium by the self assemble technique leads to [{(L)Ni}{(4,4‐bpy)Au(PPh₃)}₂](OTf)₄, ( 1,2,3 ) [{(L)Ni(4,4‐bpy)}₄](OTf)₈, ( 4,5,6 ) [L = dppm/dppe/(PPh₃)₂ = diphenyl phosphino‐methane, ‐ethane, bis‐triphenylphosphine, OSO₂CF₃ is the triflate anion]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. Ir spectra of the complexes show ‐C=C‐, ‐C=N‐, as well as phosphine stretching. The ¹H NMR spectra as well as ³¹P (¹H)NMR suggest solution stereochemistry, proton movement, and phosphorus proton interaction. Considering all the moieties, there are a lot of carbon atoms in the molecule reflected by the ¹³C NMR spectrum. In the ¹H‐¹H COSY spectrum of the present complexes and contour peaks in the ¹H^?13C HMQC spectrum, we assign the solution structure and stereoretentive transformation in each step.     

Stable ‐ESiMe3 Complexes of CuI and AgI (E=S,Se) with NHCs: Synthons in Ternary Nanocluster Assembly

As a part of efforts to prepare new “metallachalcogenolate” precursors and develop their chemistry for the formation of ternary mixed‐metal chalcogenide nanoclusters, two sets of thermally stable, N‐heterocyclic carbene metal–chalcogenolate complexes of the general formula [(IPr)Ag?ESiMe₃] (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene; E=S, 1 ; Se, 2 ) and [(iPr₂‐bimy)Cu?ESiMe₃]₂ (iPr₂‐bimy=1,3‐diisopropylbenzimidazolin‐2‐ylidene; E=S, 4 ; Se, 5 ) are reported. These are prepared from the reaction between the corresponding carbene metal acetate, [(IPr)AgOAc] and [(iPr‐bimy)CuOAc] respectively, and E(SiMe₃)₂ at low temperature. The reaction of [(IPr)Ag?ESiMe₃] 1 with mercury(II) acetate affords the heterometallic complex [{(IPr)AgS}₂Hg] 3 containing two (IPr)Ag?S^? fragments bonded to a central Hg^II, representing a mixed mercury–silver sulfide complex. The reaction of [(iPr₂‐bimy)Cu‐SSiMe₃]₂, which contains a smaller N‐heterocyclic‐carbene, with mercuric(II) acetate affords the high nuclearity cluster, [(iPr₂‐bimy)₆Cu₁₀S₈Hg₃] 6 . The new N‐heterocyclic carbene metal–chalcogenolate complexes 1 , 2 , 4 , 5 and the ternary mixed‐metal chalcogenolate complex 3 and cluster 6 have been characterized by multinuclear NMR spectroscopy (¹H and ¹³C), elemental analysis and single‐crystal X‐ray diffraction.     

Synthesis and Reactivity of Six‐Membered Oxa‐Nickelacycles: A Ring‐Opening Reaction of Cyclopropyl Ketones

Cyclopropanecarboxaldehyde ( 1 a ), cyclopropyl methyl ketone ( 1 b ), and cyclopropyl phenyl ketone ( 1 c ) were reacted with [Ni(cod)₂] (cod=1,5‐cyclooctadiene) and PBu₃ at 100 °C to give η²‐enonenickel complexes ( 2 a – c ). In the presence of PCy₃ (Cy=cyclohexyl), 1 a and 1 b reacted with [Ni(cod)₂] to give the corresponding μ‐η²:η¹‐enonenickel complexes ( 3 a , 3 b ). However, the reaction of 1 c under the same reaction conditions gave a mixture of 3 c and cyclopentane derivatives ( 4 c , 4 c′ ), that is, a [3+2] cycloaddition product of 1 c with (E)‐1‐phenylbut‐2‐en‐1‐one, an isomer of 1 c . In the presence of a catalytic amount of [Ni(cod)₂] and PCy₃, [3+2] homo‐cycloaddition proceeded to give a mixture of 4 c (76 %) and 4 c′ (17 %). At room temperature, a possible intermediate, 6 c , was observed and isolated by reprecipitation at ?20 °C. In the presence of 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr), both 1 a and 1 c rapidly underwent oxidative addition to nickel(0) to give the corresponding six‐membered oxa‐nickelacycles ( 6 ai , 6 ci ). On the other hand, 1 b reacted with nickel(0) to give the corresponding μ‐η²:η¹‐enonenickel complex ( 3 bi ). The molecular structures of 6 ai and 6 ci were confirmed by X‐ray crystallography. The molecular structure of 6 ai shows a dimeric η¹‐nickelenolate structure. However, the molecular structure of 6 ci shows a monomeric η¹‐nickelenolate structure, and the nickel(II) 14‐electron center is regarded as having “an unusual T‐shaped planar” coordination geometry. The insertion of enones into monomeric η¹‐nickelenolate complexes 6 c and 6 ci occurred at room temperature to generate η³‐oxa‐allylnickel complexes ( 8 , 9 ), whereas insertion into dimeric η¹‐nickelenolate complex 6 ai did not take place. The diastereoselectivity of the insertion of an enone into 6 c having PCy₃ as a ligand differs from that into 6 ci having IPr as a ligand. In addition, the stereochemistry of η³‐oxa‐allylnickel complexes having IPr as a ligand is retained during reductive elimination to yield the corresponding [3+2] cycloaddition product, which is consistent with the diastereoselectivity observed in Ni⁰/IPr‐catalyzed [3+2] cycloaddition reactions of cyclopropyl ketones with enones. In contrast, reductive elimination from the η³‐oxa‐allylnickel having PCy₃ as a ligand proceeds with inversion of stereochemistry. This is probably due to rapid isomerization between syn and anti isomers prior to reductive elimination.     

Aggregation and Degradation of White Phosphorus Mediated by N‐Heterocyclic Carbene Nickel(0) Complexes

The reaction of zerovalent nickel compounds with white phosphorus (P₄) is a barely explored route to binary nickel phosphide clusters. Here, we show that coordinatively and electronically unsaturated N‐heterocyclic carbene (NHC) nickel(0) complexes afford unusual cluster compounds with P₁, P₃, P₅ and P₈ units. Using [Ni(IMes)₂] [IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene], electron‐deficient Ni₃P₄ and Ni₃P₆ clusters have been isolated, which can be described as superhypercloso and hypercloso clusters according to the Wade–Mingos rules. Use of the bulkier NHC complexes [Ni(IPr)₂] or [(IPr)Ni(η⁶‐toluene)] [IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene] affords a closo‐Ni₃P₈ cluster. Inverse‐sandwich complexes [(NHC)₂Ni₂P₅] (NHC=IMes, IPr) with an aromatic cyclo‐P₅^? ligand were identified as additional products.     

Acid‐, Water‐ and High‐Temperature‐Stable Ruthenium Complexes for the Total Catalytic Deoxygenation of Glycerol to Propane

The ruthenium aqua complexes [Ru(H₂O)₂(bipy)₂](OTf)₂, [cis‐Ru(6,6′‐Cl₂‐bipy)₂(OH₂)₂](OTf)₂, [Ru(H₂O)₂(phen)₂](OTf)₂, [Ru(H₂O)₃(2,2′:6′,2′′‐terpy)](OTf)₂ and [Ru(H₂O)₃(Phterpy)](OTf)₂ (bipy=2,2′‐bipyridine; OTf^?=triflate; phen=phenanthroline; terpy= terpyridine; Phterpy=4′‐phenyl‐2,2′:6′,2′′‐terpyridine) are water‐ and acid‐stable catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOS(O)₂CF₃ (triflic acid) as a dehydration co‐catalyst they directly convert 1,2‐hexanediol to n‐hexanol and hexane. The terpyridine complexes are stable and active as catalysts at temperatures ≥250 °C and in either aqueous sulfolane solution or pure water convert glycerol into n‐propanol and ultimately propane as the final reaction product in up to quantitative yield. For the terpy complexes the active catalyst is postulated to be a carbonyl species [(4′‐R‐2,2′:6′,2′′‐terpy)Ru(CO)(H₂O)₂](OTf)₂ (R=H, Ph) formed by the decarbonylation of aldehydes (hexanal for 1,2‐hexanediol and 3‐hydroxypropanal for glycerol) generated in the reaction mixture through acid‐catalyzed dehydration. The structure of the dimeric complex [{(4′‐phenyl‐2,2′:6′,2′′‐terpy)Ru(CO)}₂(μ‐OCH₃)₂](OTf)₂ has been determined by single crystal X‐ray crystallography (Space group P (a=8.2532(17); b=12.858(3); c=14.363(3) Å; α=64.38(3); β=77.26(3); γ = 87.12(3)°, R=4.36 %).     

Variability in the Coordination Modes of 2‐Pyridineformamide Thiosemicarbazone (HAm4DH) in some Zinc(II), Cadmium(II), and Mercury(II) Complexes

The reduction of 2‐cyanopyridine by sodium in dry methanol in the presence of thiosemicarbazide produces 2‐pyridineformamide thiosemicarbazone, HAm4DH. The reactions of the potentially tridentate ligand HAm4DH with salts of Zn, Cd, and Hg gave a variety of metal‐ligand complexes. The complexes were characterized by mass spectrometry as well as IR and multinuclear NMR (¹H, ¹³C, ¹³C CP/MAS, ¹¹³Cd, ¹⁹⁹Hg) spectroscopy. The crystal structures of [Zn(Am4DH)(OAc)]₂·H₂O, [Hg(HAm4DH)₂Br₂]·C₂H₅OH and [Hg(μ‐S‐Am4DH)Br] were obtained. Coordination of anionic Am4DH^? occurs through the pyridyl nitrogen, imine nitrogen and thiolato sulfur atoms, while the neutral ligands in [Hg(HAm4DH)₂Br₂] coordinate as monodentate ligands through their thione sulfur atoms. One of the acetate ligands in [Zn(Am4DH)(OAc)]₂·H₂O is bridging monodentate and the other bridging bidentate. [Hg(μ‐S‐Am4DH)Br] features five‐coordinate mercury centers with bridging thiolato sulfur atoms. The intermolecular arrangement is dictated by hydrogen bonding from the amino groups and by π‐π stacking of the pyridine rings.     

Metal‐Free Dehydrogenation of Amine‐Boranes by Tunable N‐Heterocyclic Iminoboranes

We report the synthesis of structurally tunable boron complexes supported by N‐heterocyclic imine ligands IPr=N?BR₂ (IPr=[(HCNDipp)₂C], Dipp=2,6‐iPr₂C₆H₃, R=Cl and/or Ph) that have the ability to abstract dihydrogen from amine‐boranes, and instigate their dehydrocoupling. In one instance, mild heating of the hydrogen addition product IPr=NH?B(Ph)HCl releases H₂ to regenerate the starting N‐heterocyclic iminoborane; accordingly IPr=N?B(Ph)Cl can be used as a metal‐free catalyst to promote the dehydrocoupling of MeNH₂ ? BH₃ to yield N‐methylaminoborane oligomers [MeNH‐BH₂]_x.     

Efficient Rhodium‐Catalyzed Multicomponent Reaction for the Synthesis of Novel Propargylamines

[{Rh(μ‐Cl)(H)₂(IPr)}₂] (IPr = 1,3‐bis‐(2,6‐diisopropylphenyl)imidazole‐2‐ylidene) was found to be an efficient catalyst for the synthesis of novel propargylamines by a one‐pot three‐component reaction between primary arylamines, aliphatic aldehydes, and triisopropylsilylacetylene. This methodology offers an efficient synthetic pathway for the preparation of secondary propargylamines derived from aliphatic aldehydes. The reactivity of [{Rh(μ‐Cl)(H)₂(IPr)}₂] with amines and aldehydes was studied, leading to the identification of complexes [RhCl(CO)IPr(MesNH₂)] (MesNH₂ = 2,4,6‐trimethylaniline) and [RhCl(CO)₂IPr]. The latter shows a very low catalytic activity while the former brought about reaction rates similar to those obtained with [{Rh(μ‐Cl)(H)₂(IPr)}₂]. Besides, complex [RhCl(CO)IPr(MesNH₂)] reacts with an excess of amine and aldehyde to give [RhCl(CO)IPr{MesN?CHCH₂CH(CH₃)₂}], which was postulated as the active species. A mechanism that clarifies the scarcely studied catalytic cycle of A₃‐coupling reactions is proposed based on reactivity studies and DFT calculations.     

Synthesis of LnII‐in‐Cryptand Complexes by Chemical Reduction of LnIII‐in‐Cryptand Precursors: Isolation of a NdII‐in‐Cryptand Complex

Lanthanide triflates have been used to incorporate Nd^III and Sm^III ions into the 2.2.2‐cryptand ligand (crypt) to explore their reductive chemistry. The Ln(OTf)₃ complexes (Ln=Nd, Sm; OTf=SO₃CF₃) react with crypt in THF to form the THF‐soluble complexes [Ln^III(crypt)(OTf)₂][OTf] with two triflates bound to the metal encapsulated in the crypt. Reduction of these Ln^III‐in‐crypt complexes using KC₈ in THF forms the neutral Ln^II‐in‐crypt triflate complexes [Ln^II(crypt)(OTf)₂]. DFT calculations on [Nd^II(crypt)]²⁺], the first Nd^II cryptand complex, assign a 4f⁴ electron configuration to this ion.     

Zinc(II) complexes of Triaza and Amidinate ligands: Efficient initiators for the ring‐opening polymerization of ε‐Caprolactone and rac‐Lactide

Zinc complexes supported by tertiary 1,3,5‐triazapenta‐1,3‐dienate ligand (L¹) and N ‐benzoyl‐N′ ‐arylbenzamidinate [aryl =2,6‐diisopropylphenyl (L²), phenyl (L³)] ligands have been synthesized and characterized. The reaction of L¹H with ZnEt₂ affords a mononuclear zinc complex [L¹ZnEt] ( 1 ) in good yield. Tetra nuclear zinc complex [(L¹)₂Zn₄O(OAc)₄] ( 2 ) is prepared by treating L¹H with one equivalent of Zn(OAc)₂ in toluene. Further, dinuclear zinc complexes [L²ZnEt]₂ ( 3 ) and [L³ZnEt]₂ ( 4 ) are obtained in good yields from L²H and L³H with ZnEt₂ in toluene respectively_. The complexes 1–4 have been characterized by ¹H/¹³C NMR spectroscopy and single crystal X‐ray diffraction studies. All of the complexes have been explored for their catalytic activity toward the ring‐opening polymerization (ROP) of ε ‐caprolactone. It has been found that complex 1 is an active catalyst for the polymerization of ε ‐caprolactone in presence of a cocatalyst benzyl alcohol (BnOH). While complex 2 is as active as 1 there is no need for a cocatalyst for the polymerization to proceed. Dinuclear zinc complexes 3 and 4 show very high activity for the ROP of ε ‐caprolactone (CL) and rac ‐lactide (LA) without requiring a cocatalyst. The resultant polymers are found to have very high molecular weight (M _n = 296 X 10³ g mol⁻¹) and relatively narrow polydispersity index compared to 1 and 2 .     

Metal Derivatives of 1,3‐Imidazolidine‐2‐thione with Divalent d10 Metal Ions (Zn–Hg) : Synthesis and Structures

Reactions of divalent Zn‐Hg metal ions with 1,3‐imidazolidine‐2‐thione (imdtH₂) in 1 : 2 molar ratio have formed monomeric complexes, [Zn(η¹‐S‐imdtH₂)₂(OAc)₂] ( 1 ), [Cd((η¹‐SimdtH₂)₂I₂] ( 2 ), [Cd(η¹‐S‐imdtH₂)₂Br₂] ( 3 ), and [Hg(η¹‐S‐imdtH₂)₂I₂] ( 4 ). Complexes 1 – 4 , have been characterized by elemental analysis (C, H, N), spectroscopy (IR, ¹H, NMR) and x‐ray crystallography ( 1 ‐ 4 ). Hydrogen bonding between oxygen of acetate and imino hydrogen of ligand, {N(2)–H(2C)···O(2)^#} in 1 , ring CH and imino hydrogen, {C(2A)–H(2A)···Br(2)^#} in 3 have formed H‐bonded dimers. Similarly, the interactions between molecular units of complexes 2 and 4 have yielded 2D polymers. The polymerization occurs via intermolecular interactions between thione sulfur and imino hydrogen, {N(2)–H(2)···S(1)^#}, imino hydrogen and the iodine atom, {NH(1)···I(2)^#} in 2 and imino hydrogen – iodine atom {N(2A)–H(2A)···I(2)} and I···I interaction in 4 . Crystal data: [Zn(η¹‐S‐imdtH₂)₂(OAc)₂] ( 1 ), C₁₀H₁₈N₄O₄S₂Zn, orthorhombic, Pbcn, a = 9.3854(7) Å, b = 12.4647(10) Å, c = 13.2263(11) Å; V = 1547.3(2) ų, Z = 4, R = 0.0280 [Cd((η¹‐S‐imdtH₂)₂I₂] ( 2 ), C₆H₁₂CdI₂N₄S₂, orthorhombic, Pnma, a = 13.8487(10) Å, b = 14.4232(11) Å, c = 7.0659(5) Å; Z = 4, V = 1411.36(18) ų, R = 0.0186.     

Exploring Excited‐State Tunability in Luminescent Tris‐cyclometalated Platinum(IV) Complexes: Synthesis of Heteroleptic Derivatives and Computational Calculations

The synthesis, structure, electrochemistry, and photophysical properties of a series of heteroleptic tris‐ cyclometalated Pt^IV complexes are reported. The complexes mer‐[Pt(C^N)₂(C′^N′)]OTf, with C^N=C‐deprotonated 2‐(2,4‐difluorophenyl)pyridine (dfppy) or 2‐phenylpyridine (ppy), and C′^N′=C‐deprotonated 2‐(2‐thienyl)pyridine (thpy) or 1‐phenylisoquinoline (piq), were obtained by reacting bis‐ cyclometalated precursors [Pt(C^N)₂Cl₂] with AgOTf (2 equiv) and an excess of the N′^C′H pro‐ligand. The complex mer‐[Pt(dfppy)₂(ppy)]OTf was obtained analogously and photoisomerized to its fac counterpart. The new complexes display long‐lived luminescence at room temperature in the blue to orange color range. The emitting states involve electronic transitions almost exclusively localized on the ligand with the lowest π–π* energy gap and have very little metal character. DFT and time‐dependent DFT (TD‐DFT) calculations on mer‐[Pt(ppy)₂(C′^N′)]⁺ (C′^N′=thpy, piq) and mer/fac‐[Pt(ppy)₃]⁺ support this assignment and provide a basis for the understanding of the luminescence of tris‐cyclometalated Pt^IV complexes. Excited states of LMCT character may become thermally accessible from the emitting state in the mer isomers containing dfppy or ppy as chromophoric ligands, leading to strong nonradiative deactivation. This effect does not operate in the fac isomers or the mer complexes containing thpy or piq, for which nonradiative deactivation originates mainly from vibrational coupling to the ground state.     

P−P Condensation and P−N/P−P Bond Metathesis: Facile Synthesis of Cationic Tri‐ and Tetraphosphanes

[L_C^RP((PhP)₂C₂H₄)][OTf] ( 4 a,b [OTf]) and [L_C^iPrP(PPh₂)₂][OTf] ( 5 b [OTf]) were prepared from the reaction of imidazoliumyl‐substituted dipyrazolylphosphane triflate salts [L_C^RP(pyr)₂][OTf] ( 3 a,b [OTf]; a : R=Me, b =iPr; L_C^R=1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐yl; pyr=3,5‐dimethylpyrazol‐1‐yl) with the secondary phosphanes PhP(H)C₂H₄P(H)Ph) and Ph₂PH. A stepwise double P?N/P?P bond metathesis to catena‐tetraphosphane‐2,3‐diium triflate salt [(Ph₂P)₂(L_C^MeP)₂][OTf]₂ ( 7 a [OTf]₂) is observed when reacting 3 a [OTf] with diphosphane P₂Ph₄. The coordination ability of 5 b [OTf] was probed with selected coinage metal salts [Cu(CH₃CN)₄]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph₂PPL_C^iPr)Au}₄][OTf]₄ ( 9 [OTf]₄) was unexpectedly formed as a result of a chloride‐induced P?P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [( 5 b )M(CH₃CN)₃][OTf]₂ (M=Cu, Ag) ( 10 [OTf]₂, 11 [OTf]₂).     

Well‐defined NHC?Pd complex‐mediated intermolecular direct annulations for synthesis of functionalized indoles (NHC = N‐hetero‐cyclic carbene)

As alternatives to the common tertiary phosphine/Pd systems, well‐defined N‐heterocyclic carbene–Pd complexes have been proven to be highly efficient precatalysts for intermolecular direct annalution of o‐haloanilines and ketones at lower catalyst loadings. A highly efficient and practical protocol for synthesis of functionalized indoles was developed using (IPr)Pd(acac)Cl as catalyst. Both o‐bromoanilines and o‐chloroanilines gave rise to efficient coupling under the reaction conditions. Related to acyclic ones, cyclic ketones coupled more effectively with o‐haloanilines. With [Pd(IPr)₂] as catalyst, the base‐sensitive groups including OH and CO₂H groups could be tolerated. Copyright © 2011 John Wiley & Sons, Ltd.