Proton‐Assisted Hydrogen Activation on Polyhedral Cations

The treatment of [1,1‐(PR₃)₂‐3‐(Py)‐closo‐1,2‐RhSB₉H₈] (PR₃=PMe₃ ( 2 ) or PPh₃ and PMe₃ ( 3 ); Py=pyridine) with triflic acid (TfOH) affords [1,3‐μ‐(H)‐1,1‐(PR₃)₂‐3‐(Py)‐1,2‐RhSB₉H₈]⁺ (PR₃=PMe₃ ( 4 ) or PMe₃ and PPh₃ ( 5 )). These products result from the protonation of the 11‐vertex closo‐cages along the Rh(1)? B(3) edge. These unusual cationic rhodathiaboranes are stable in solution and in the solid state and they have been fully characterized by multinuclear NMR spectroscopy. In addition, compound 5 was characterized by single‐crystal X‐ray diffraction. One remarkable feature in these structures is the presence of three {Rh(PPh₃)(PMe₃)}‐to‐{ηⁿ‐SB₉H₈(Py)} (n=4 or 5) conformers in the unit cell, thus giving an uncommon case of conformational isomerism. [1,1‐(PPh₃)₂‐3‐(Py)‐closo‐1,2‐RhSB₉H₈] ( 1 ), that is, the bis‐PPh₃‐ligated analogue of compounds 2 and 3 , is also protonated by TfOH, but, in marked contrast, the resulting cation, [1,3‐μ‐(H)‐1,1‐(PPh₃)₂‐3‐(Py)‐1,2‐RhSB₉H₈]⁺ ( 6 ), is attacked by a triflate anion with the release of a PPh₃ ligand and the formation of [8,8‐(OTf)(PPh₃)‐9‐(Py)‐nido‐8,7‐RhSB₉H₉] ( 9 ). The result is an equilibrium that involves cationic species 6 , neutral OTf‐ligated compound 9 , and [HPPh₃]⁺, which is formed upon protonation of the released PPh₃ ligand. The resulting ionic system reacts readily with H₂ to give cationic species [8,8,8‐(H)(PPh₃)₂‐9‐(Py)‐nido‐8,7‐RhSB₉H₉]⁺ ( 7 ). This reactivity is markedly higher than that previously found for compound 1 and it introduces a new example of proton‐assisted H₂ activation that occurs on a polyhedral boron‐containing compound.     

Establishing the Coordination Chemistry of Antimony(V) Cations: Systematic Assessment of Ph4Sb(OTf) and Ph3Sb(OTf)2 as Lewis Acceptors

The coordination chemistry of the stiboranes Ph₄Sb(OTf) ( 1 a , OTf = OSO₂CF₃) and Ph₃Sb(OTf)₂ ( 3 ) with Lewis bases has been investigated. The significant steric encumbrance of the Sb center in 1 a precludes interaction with most ligands, but the relatively low steric demands of 4‐methylpyridine‐N‐oxide (OPyrMe) and OPMe₃ enabled the characterization of [Ph₄Sb(OPyrMe)][OTf] ( 2 a ) and [Ph₄Sb(OPMe₃)][OTf] ( 2 b ), rare examples of structurally characterized complexes of stibonium acceptors. In contrast, 3 was found to engage a variety of Lewis bases, forming stable isolable complexes of the form [Ph₃Sb(donor)₂][OTf]₂ [donor=OPMe₃ ( 6 a ), OPCy₃ ( 6 b , Cy=cyclohexyl), OPPh₃ ( 6 c ), OPyrMe ( 6 d )], [Ph₃Sb(dmap)₂(OTf)][OTf] ( 6 e , dmap=4‐(dimethylamino)pyridine) and [Ph₃Sb(donor)(OTf)][OTf] [donor=1,10‐phenanthroline ( 7 a ) or 2,2′‐bipy ( 7 b , bipy=bipyridine)]. These compounds exhibit significant structural diversity in the solid‐state, and undergo ligand exchange reactions in line with their assignment as coordination complexes. Compound 3 did not form stable complexes with phosphine donors, with reactions instead leading to redox processes yielding SbPh₃ and products of phosphine oxidation.     

A Tetrameric Neodymium Silanolate: [Nd(OSiMe3)3]4

The title compound [Nd(OSiMe₃)₃]₄ ( 1 ) was prepared by reaction of [Nd{N(SiMe₃)₂}₃] with Me₃SiOH in toluene at room temperature. Compound 1 crystallized from a concentrated toluene solution in the monoclinic space group P2₁/n with the lattice constants a = 15.144(1) Å, b = 25.142(1) Å, c = 20.391(1) Å and β = 103.755(2)°. In the solid state a tetramer is observed which shows Nd‐O bond distances in the range 2.129(2)‐2.675(2) Å.     

Stabilization of the Triphosphallyl Ligand η3‐P3{P(O)H} at Iridium via Alkaline Activation of P4

The selective functionalization of the polyphosphorus moiety Ph₂PCH₂PPh₂PPPP present as a tetrahapto‐ligand in complex [Ir(dppm)(Ph₂PCH₂PPh₂PPPP)]⁺ ( 1 , dppm=Ph₂PCH₂PPh₂) was obtained by reaction of 1 with water under basic conditions at room temperature. The formation of the new triphosphaallyl moiety η³‐P₃{P(O)H} was determined in solution by NMR spectroscopy, and confirmed in the solid state by a single‐crystal X‐ray structure of the stable product [Ir(κ²‐dppm)(κ¹‐dppm)(η³‐P₃{P(O)H})] ( 2 ). In solution, 2 has a fluxional behavior attributable to the four P atoms belonging to the tetraphosphorus moiety in 1 and exhibits a chemical exchange process involving the two PPh₂ moieties of the same bidentate ligand, as determined by 1D and 2D NMR spectroscopy experiments carried out at variable temperature. The mechanism of the reaction was investigated at the DFT level, which suggested a selective attack of an in‐situ generated OH^? anion on one of the non‐coordinated phosphorus atoms of the P₄ moiety. The reaction then evolves through an acid‐assisted tautomerization, which leads to the final compound 2 . Bonding analysis pointed out that the new unsubstituted P₃‐unit in the η³‐P₃{P(O)H} moiety behaves as a triphosphallyl ligand.     

Deprotonation of Coordinated Phosphanes in a Rhenium Complex: CC Coupling with Diimine Coligands

The reaction of fac‐[Re(bipy)(CO)₃(PMe₃)][OTf] (bipy=2,2′‐bipyridine) with KN(SiMe₃)₂ affords two neutral products: cis,trans‐[Re(bipy)(CO)₂(CN)(PMe₃)], and a thermally unstable compound, which features a new C?C bond between a P‐bonded methylene group (from methyl group deprotonation) and the C6 position of bipy. The solid‐state structures of more stable 1,2‐bis[(2,6‐diisopropylphenyl)imino]acenaphthene analogs, resulting from the deprotonation of PMe₃, PPhMe₂, and PPh₂Me ligands, are determined by X‐ray diffraction.     

Synthesis of an Iron(IV) Aqua–Oxido Complex Using Ozone as an Oxidant

The iron(IV) oxido complex [(tmc)Fe=O(OTf)]OTf with the macrocyclic ligand 1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclo‐tetradecane (tmc) has been synthesized using ozone as an oxidant. By adding water to this compound the complex [(H₂O)(tmc)Fe=O)](OTf)₂ could be prepared. This complex is important in regard to a better understanding of the reactivity of Fe^IV oxido complexes. Mössbauer measurements using the solid compound showed an isomer shift of δ=0.19 mm s^?1 and a quadrupole splitting ΔE_Q=1.38 mm s^?1, confirming the high‐valent Fe^IV state. DFT calculations were performed and led to an assignment of triplet spin multiplicity. Crystallographic characterization of [(H₂O)(tmc)Fe=O)](OTf)₂ as well as of starting materials [(tmc)Fe(CH₃CN)](OTf)₂ and [(tmc)Fe(OTf)]OTf together with previous results strongly suggest that [(H₂O)(tmc)Fe=O)](OTf)₂ was formed similar to the oxido–hydroxido tautomerism analogous to heme systems.     

Synthesis and Characterization of Three Homoleptic Bismuth Silanolates: [Bi(OSiR3)3] (R = Me,Et, iPr)

The bismuth tris(triorganosilanolates) [Bi(OSiR₃)₃] ( 1 , R = Me; 2 , R = Et; 3 , R = iPr) were prepared by reaction of R₃SiOH with [Bi(OtBu)₃]. Compound 1 crystallizes in the triclinic space group with Z = 2 and the lattice constants a = 10.323(1) Å, b = 13.805(1) Å, c = 21.096(1) Å and α = 91.871(4)°, β = 94.639(3)°, γ = 110.802(3)°. In the solid state compound 1 is a trimer as result of weak intermolecular bismuth‐oxygen interactions with Bi–O distances in the range 2.686(6)–3.227(3) Å. The coordination at the bismuth atoms Bi(1) and Bi(3) is best described as 3 + 2 coordination whereas Bi(2) shows a 3 + 3 coordination. The intramolecular Bi–O distances fall in the range 2.041(3)–2.119(3) Å. Compound 3 crystallizes in the orthorhombic space group Pbcm with Z = 4 and the lattice constants a = 7.201(1) Å, b = 23.367(5) Å and c = 20.893(1) Å, whereas the triethylsilyl‐derivative 2 is liquid. In contrast to [Bi(OSiMe₃)₃] ( 1 ) compound 3 is monomeric in the solid state, but shows similar intramolecular Bi–O distances in the range 1.998(2)–2.065(5) Å. The bismuth silanolates are highly soluble in common organic solvents and strongly moisture sensitive. Compound 1 shows the lowest thermal stability.     

Mononuclear Complexes of Platinum Group Metals Containing η6‐ and η5‐Cyclic Π‐Perimeter Hydrocarbon and Pyridylpyrazolyl Derivatives: Syntheses and Structural Studies

Piano‐stool‐shaped platinum group metal compounds, stable in the solid state and in solution, which are based on 2‐(5‐phenyl‐1H‐pyrazol‐3‐yl)pyridine ( L ) with the formulas [(η⁶‐arene)Ru( L )Cl]PF₆ {arene = C₆H₆ ( 1 ), p‐cymene ( 2 ), and C₆Me₆, ( 3 )}, [(η⁶‐C₅Me₅)M( L )Cl]PF₆ {M = Rh ( 4 ), Ir ( 5 )}, and [(η⁵‐C₅H₅)Ru(PPh₃)( L )]PF₆ ( 6 ), [(η⁵‐C₅H₅)Os(PPh₃)( L )]PF₆ ( 7 ), [(η⁵‐C₅Me₅)Ru(PPh₃)( L )]PF₆ ( 8 ), and [(η⁵‐C₉H₇)Ru(PPh₃)( L )]PF₆ ( 9 ) were prepared by a general method and characterized by NMR and IR spectroscopy and mass spectrometry. The molecular structures of compounds 4 and 5 were established by single‐crystal X‐ray diffraction. In each compound the metal is connected to N1 and N11 in a k² manner.     

The Versatile Coordination Modes of Monophosphine‐o‐Carborane in the Formation of Iridium and Rhodium Complexes: Synthesis,Reactivity, and Characterization

Monophosphine‐o‐carborane has four competitive coordination modes when it coordinates to metal centers. To explore the structural transitions driven by these competitive coordination modes, a series of monophosphine‐o‐carborane Ir,Rh complexes were synthesized and characterized. [Cp*M(Cl)₂{1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁}] (M=Ir ( 1 a ), Rh ( 1 b ); Cp*=η⁵‐C₅Me₅), [Cp*Ir(H){7‐(PPh₂)‐7,8‐C₂B₉H₁₁}] ( 2 a ), and [1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 3 a ), Rh ( 3 b )) can be all prepared directly by the reaction of 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ with dimeric complexes [(Cp*MCl₂)₂] (M=Ir, Rh) under different conditions. Compound 3 b was treated with AgOTf (OTf=CF₃SO₃^?) to afford the tetranuclear metallacarborane [Ag₂(thf)₂(OTf)₂{1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐RhC₂B₉H₁₀}₂] ( 4 b ). The arylphosphine group in 3 a and 3 b was functionalized by elemental sulfur (1 equiv) in the presence of Et₃N to afford [1‐{(S)PPh₂}‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 5 a ), Rh ( 5 b )). Additionally, the 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ ligand was functionalized by elemental sulfur (2 equiv) and then treated with [(Cp*IrCl₂)₂], thus resulting in two 16‐electron complexes [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₉)] ( 6 a ) and [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐9‐OCH₃‐7,8‐C₂B₉H₉)] ( 7 a ). Compound 6 a further reacted with nBuPPh₂, thereby leading to 18‐electron complex [Cp*Ir(nBuPPh₂)(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₁₀)] ( 8 a ). The influences of other factors on structural transitions or the formation of targeted compounds, including reaction temperature and solvent, were also explored.     

[(bmpyr)2{Zn(OC6H3(NO2)2)4}]: Influence of an Ionic Liquid on Liquid/Liquid Extraction of Metal Ions in a Biphasic System

The compound [(bmpyr)₂{Zn(OR)₄}] (OR = 2,4‐dinitriphenolate) has been prepared from Zn(NO₃)₂·6H₂O and sodium 2,4‐dinitrophenolate in a biphasic aqueous ionic liquid (Butyl‐methyl‐pyrrolidinium trifluoromethylsulfonate [bmpyr][OTf]) system. The presence of the anionic zinc complex in [bmpyr][OTf] is made possible by the exchange of the ionic liquid anions into the aqueous phase for the zinc complex. [(bmpyr)₂{Zn(OR)₄}] was characterized in solution by ¹³C‐ and ¹H‐NMR spectroscopy and in the solid state by crystal structure determination. The zinc complex represents the first type of a zinc complex with more than two phenolate ligands.     

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.     

The Coordination Chemistry of the Ylide Adduct O2CC(PPh3)2; Preparation,Crystal Structures,and Spectroscopic Properties of [Cl3In{O2CC(PPh3)2}], [Cl2Sn{O2CC(PPh3)2}], and [I2In{O2CC(PPh3)2}2]I

The betain like carbodiphosphorane CO₂ adduct O₂CC(PPh₃)₂ ( 1a ) can serve as a ligand versus hard Lewis acids from main group compounds. Thus, reaction of 1a with InCl₃, InI₃ and SnCl₂ in polar solvents leads to the addition compounds [Cl₃In{O₂CC(PPh₃)₂}] ( 2 ), [Cl₂SnO₂CC(PPh₃)₂}] ( 3 ) and the salt like compound [I₂In{O₂CC(PPh₃)₂}₂]I ( 4 ) in good yields. Whereas in the indium compounds 1a acts as a chelating ligand, in the tin compound the molecule coordinates with one oxygen atom only as a monodentate ligand. 4 has a pyramidal structure with a stereochemical active pair of electrons. All compounds could be characterized by X‐ray analyses and the usual spectroscopic methods.     

Two azo pigments based on β‐naphthol

There has been much discussion in the literature of the azo–hydrazone tautomerism of pigments. All commercial azo pigments with β‐naphthol as the coupling compound adopt the hydrazone tautomeric form (Ph—NH—N=C) in the solid state. In contrast, the red pigments 1‐[4‐(dimethylamino)phenyldiazenyl]‐2‐naphthol, C₁₈H₁₇N₃O, (1a), and 1‐[4‐(diethylamino)phenyldiazenyl]‐2‐naphthol, C₂₀H₂₁N₃O, (1b), have been reported to be azo tautomers or a mixture of azo and hydrazone tautomers in the solid state. To prove these observations, both compounds were synthesized, recrystallized and their crystal structures redetermined by single‐crystal structure analysis. Difference electron‐density maps show that the H atoms of the hydroxyl groups are indeed bonded to the O atoms. Nevertheless, a small amount of the hydrazone form seems to be present. Hence, the compounds are close to being `real' azo compounds. Compound (1a) crystallizes with a herring‐bone structure and compound (1b) forms a rare double herring‐bone structure.     

[1‐Me‐1‐closo‐SnB11H11]− as a potential weakly coordinating anion: Synthesis of Rh(PPh3)2(1‐Me‐closo‐SnB11H11) and comparisons with Rh(PR3)2 (1‐H‐closo‐CB11 H11)

The closo‐stannaborane salt [Rh(PPh₃)₂‐(nbd)][1‐Me‐1‐closo‐SnB₁₁H₁₁] reacts with H₂ in CH₂ Cl₂ solution to afford the contact ion‐pair Rh(PPh₃)₂(1‐Me‐closo‐SnB₁₁H₁₁), which has been characterized in solution and the solid state by X‐ray diffraction. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:174–180, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20218     

Formation and Crystal Structure of the Salt (IC(PPh3)2)2I[I3]·(I2)2 with a new Polyiodide Chain

The reaction of the carbodiphosphorane Ph₃P=C=PPh₃ ( 1 ) with MeI in the presence of iodine gives the oxidation product (IC(PPh₃)₂)₂I[I₃]·(I₂)₂ ( 2 ). In the solid state dimeric units linked by indefinite ···I^?···I₂···I₃^?···I₂···I^?··· chains are found. An additional I···I contact between the cation and the I₂ molecule is formed, amounting to 359.23(5) pm. 2 crystallizes in the monoclinic space group P2/c, with the unit cell dimensions a = 2053.9(1), b = 1011.4(1), c = 1889.8(1) pm; β = 105.21(1)° and Z = 4.     

On the Reactivity of Silylated Ge9 Clusters: Synthesis and Characterization of [ZnCp*(Ge9{Si(SiMe3)3}3)], [CuPiPr3(Ge9{Si(SiMe3)3}3)], and [(CuPiPr3)4{Ge9(SiPh3)2}2]

We report on the synthesis of new derivatives of silylated clusters of the type [Ge₉(SiR₃)₃]^? (R = SiMe₃, Me = CH₃; R = Ph, Ph = C₆H₅) as well as on their reactivity towards copper and zinc compounds. The silylated cluster compounds were synthesized by heterogeneous reactions starting from the Zintl phase K₄Ge₉. Reaction of K[Ge₉{Si(SiMe₃)₃}₃] with ZnCl₂ leads to the already known dimeric compound [Zn(Ge₉{Si(SiMe₃)₃}₃)₂] ( 1 ), whereas upon the reaction with [ZnCp*₂] the coordination of [ZnCp*]⁺ to the cluster takes place (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) under the formation of [ZnCp*(Ge₉{Si(SiMe₃)₃}₃)] ( 2 ). A similar reaction leads to [CuPiPr₃(Ge₉{Si(SiMe₃)₃}₃)] ( 3 ) from [CuPiPr₃Cl] (iPr=isopropyl). Further we investigated the novel silylated cluster units [Ge₉(SiPh₃)₃]^? ( 4 ) and [Ge₉(SiPh₃)₂]^? ( 5 ), which could be identified by mass spectroscopy. Bis‐ and tris‐silylated species can be synthesized by the respective stoichiometric reactions, and the products were characterized by ESI‐MS and NMR experiments. These clusters show rather different reactivity. The reaction of the tris‐silylated anion 4 with [CuPiPr₃Cl] leads to [(CuPiPr₃)₃Ge₉(SiPh₃)₂]⁺ as shown from NMR experiments and to [(CuPiPr₃)₄{Ge₉(SiPh₃)₂}₂] ( 6 ), which was characterized by single‐crystal X‐ray diffraction. Compound 6 shows a new type of coordination of the Cu atoms to the silylated Zintl clusters.     

Studies on solid state reactions of coordination compounds. XLVII. Solid state syntheses and crystal structures of cluster compounds {Cu3MoS3I} (PPh3)3S and {Cu3WS3Br} (PPh3)3S

Reactions of [NH⁴]₂[MS₄](M = Mo,W), CuX(X = Br, I) and PPh₃ in the solid state produced four mixed-metal sulfur containing clusters {Cu₃MS₃X}(PPh₃)₃S(M = Mo, W; X = Br, I), two of which (1: M = Mo, X = I; 2: M = W, X = Br) were structurally determined. Crystals of 1 and 2 are triclinic, space group P1 (1: a = 11.895(3), b = 13.107(1), c = 20.473(2)Å, α = 74.95(6), β = 84.87(8), γ = 64.27(7)°, Z=2, V=2776.1 ų, R_w = 0.064 for 6443 observed reflections. 2: a = 11.876 (1), b = 13.065 (2), c = 20.325(2)Å, α = 74.95(1), β= 85.39(1), γ = 64.09(1)°, Z = 2, V = 2737.3ų, R_w = 0.055 for ·5303 observed reflections). The results of the structure determination showed that the central units of the two cubane-like cluster compounds are composed of four metal atoms and four non-metal atoms situated at alternate corners. The differences of cubane-like cluster compounds obtained from solid state reactions and from solution reactions are discussed.     

Effect of the Nature of the Substituent in N‐Alkylimidazole Ligands on the Outcome of Deprotonation: Ring Opening versus the Formation of N‐Heterocyclic Carbene Complexes

Complexes [Re(CO)₃(N‐RIm)₃]OTf (N‐RIm=N‐alkylimidazole, OTf=trifluoromethanesulfonate; 1 a – d ) have been straightforwardly synthesised from [Re(OTf)(CO)₅] and the appropriate N‐alkylimidazole. The reaction of compounds 1 a – d with the strong base KN(SiMe₃)₂ led to deprotonation of a central C? H group of an imidazole ligand, thus affording very highly reactive derivatives. The latter can evolve through two different pathways, depending on the nature of the substituents of the imidazole ligands. Compound 1 a contains three N‐MeIm ligands, and its product 2 a features a C‐bound imidazol‐2‐yl ligand. When 2 a is treated with HOTf or MeOTf, rhenium N‐heterocyclic carbenes (NHCs) 3 a or 4 a are afforded as a result of the protonation or methylation, respectively, of the non‐coordinated N atom. The reaction of 2 a with [AuCl(PPh₃)] led to the heterobimetallic compound 5 , in which the N‐heterocyclic ligand is once again N‐bound to the Re atom and C‐coordinated to the gold fragment. For compounds 1 b – d , with at least one N‐arylimidazole ligand, deprotonation led to an unprecedented reactivity pattern: the carbanion generated by the deprotonation of the C2? H group of an imidazole ligand attacks a central C? H group of a neighbouring N‐RIm ligand, thus affording the product of C? C coupling and ring‐opening of the imidazole moiety that has been attacked ( 2 c , d ). The new complexes featured an amido‐type N atom that can be protonated or methylated, thus obtaining compounds 3 c , d or 4 c , d , respectively. The latter reaction forces a change in the disposition of the olefinic unit generated by the ring‐opening of the N‐RIm ligand from a cisoid to a transoid geometry. Theoretical calculations help to rationalise the experimental observation of ring‐opening (when at least one of the substituents of the imidazole ligands is an aryl group) or tautomerisation of the N‐heterocyclic ligand to afford the imidazol‐2‐yl product.     

Synthesis and Characterization of New Copper(I) Complexes Containing Thione Derivatives of 1, 2, 4‐Triazine. Crystal Structure of [Cu(PPh3)2(ATTO)]NO3 (ATTO = 4‐amino‐1, 2, 4‐triazin‐3(2H)‐thione‐5‐one)

The reaction of 4‐amino‐1, 2, 4‐triazin‐3(2H)‐thione‐5‐one (ATTO, 1 ) with [Cu(PPh₃)₂]NO₃ in ethanol led to the complex [Cu(PPh₃)₂(ATTO)]NO₃ ( 2 ). 2 was characterized by elemental analyses, IR, ¹H NMR and Raman spectroscopy. A single‐crystal X‐ray diffraction of compound 2 revealed that ATTO acts as a bidentate ligand via its nitrogen and sulfur atoms. Crystal data for 2 at 20 °C: space group P2₁/n with a = 975.7(1), b = 1533.5(2), c = 2504.2(3) pm, β = 92.25(1)°, Z = 4, R₁ = 0.0632.     

A New Copper(I) Complex Based on Imidazole and Triphenylphosphine Ligands: Synthesis,Structure, Third‐Order NLO,and Fluorescence Properties

A new candidate [Cu(PPh₃)₂Him]Br ( 1 , PPh₃=triphenylphosphine, Him=1‐H‐imidazole) for nonlinear optical (NLO) materials has been synthesized and characterized crystallographically. The third‐order NLO optical properties were measured by the Z‐scan technique with an 8 ns pulsed laser at 532 nm. Compound 1 exhibits strong NLO absorptive abilities [α₂=(61±5)×10^?12] and effective self‐focusing performance [n₂=(15±3)×10^?18 m²·W^?1] in 1.01×10^?4 mol·dm^?3 DMF solution. The compound also exhibits luminescence in DMF solution at room temperature and shows narrow emission with maximum at 382 nm. The electronic structure and photoluminescent process were investigated by means of TD‐DFT calculations. The results suggest that the contribution to the frontier orbitals from the Cu? Br δ bond plays a crucial role in its linear optical properties, and the origin of luminescence is attributable to the π??→n transitions.