A new phenylimidorhenium(V) compound containing the 2-[(2-hydroxyethylimino)methyl]phenol Schiff-base ligand: experimental and theoretical aspects

Reaction of equimolar trans-[Re(NPh)(PPh₃)₂Cl₃] with H₂L, a 1?:?1 Schiff-base condensate of salicylaldehyde and ethanolamine, in chloroform gives trans-[Re(NPh)(HL)(PPh₃)Cl₂] (1a) in good yield. 1a has been characterized by C, H, and N microanalyses, FTIR and UV–vis spectra. The X-ray crystal structure of 1a reveals that it is an octahedral trans-Cl,Cl phenylimidorhenium(V) complex. The rhenium center has an ‘N₂OCl₂P’ coordination sphere. 1a crystallizes in the monoclinic space group P2₁/c with a = 11.2391(5), b = 16.4848(7), c = 16.3761(8) Å, V = 3034.0(2) ų and Z = 4. The electrochemical aspects of 1a have been studied. Electrochemical studies of 1a in dichloromethane show a quasi-reversible Re(V) to Re(VI) oxidation at 1.128 V versus Ag/AgCl. This redox potential reasonably matches the calculated redox potential, 1.186 V versus Ag/AgCl. Geometry optimization of the trans-Cl,Cl 1a vis-à-vis its cis analog, cis-Cl,Cl 1b, have been performed at the level of density functional theory (DFT). It is revealed that 1a is more stable than 1b by 21.6 kcal per mole of energy in the gas phase.     

Phenylimidorhenium(V) Complexes with 1,3‐Diethyl‐4,5‐dimethylimidazole‐2‐ ylidene Ligands

The phenylimidorhenium(V) complexes [Re(NPh)X₃(PPh₃)₂] (X = Cl, Br) react with the N‐heterocyclic carbene (NHC) 1,3‐diethyl‐4,5‐dimethylimidazole‐2‐ylidene (L^Et) under formation of the stable rhenium(V) complex cations [Re(NPh)X(L^Et)₄]²⁺ (X = Cl, Br), which can be isolated as their chloride or [PF₆]^? salts. The compounds are remarkably stable against air, moisture and ligand exchange. The hydroxo species [Re(NPh)(OH)(L^Et)₄]²⁺ is formed when moist solvents are used during the synthesis. The rhenium atoms in all three complexes are coordinated in a distorted octahedral fashion with the four NHC ligands in equatorial planes of the molecules. The Re–C(carbene) bond lengths between 2.171(8) and 2.221(3) Å indicate mainly σ‐bonding between the NHC ligand and the electron deficient d² metal atoms. Attempts to prepare analogous phenylimido complexes from [Re(NPh)Cl₃(PPh₃)₂] and 1,3‐diisopropyl‐4,5‐dimethylimidazole‐2‐ylidene (L^i?Pr) led to a cleavage of the rhenium‐nitrogen multiple bond and the formation of the dioxo complex [ReO₂(L^i?Pr)₄]⁺.     

Organoimido complexes of tungsten and rhenium: Oxo-imido and bis-imido complexes of tungsten(VI), and phenylimido complexes of rhenium(VI) and (V). The X-ray crystal structures of [W(NCMe3)(NPh)Cl2(bipy)] and [Re(NPh)Cl3(NH2CMe3)2]

Reaction of Me₃CNH₂ or Me₃SiNHCMe₃ with WOCl₄ gives a mixture containing [W(O)(NCMe₃)Cl₂(NH₂CMe₃)]_x which on further reaction with 2,2′-bipyridyl (bipy) gives [W(NCMe₃)₂Cl₂(bipy)] and insoluble oxo complexes. Reaction of WOCl₄ with p-MeC₆H₄N(SiMe₃)₂ and then bipy gives [W(NC₆H₄Me-p)₂Cl₂(bipy)] and [W(O)(NC₆H₄Me-p)Cl₂(bipy)]; [W(NPh)Cl₄]₂ reacts with p-MeC₆H₄N(SiMe₃)₂ and then bipy to give [W(NPh)(NC₆H₄Me-p)Cl₂(bipy)]. [W(NCMe₃)(μ-NPh)Cl₂(NH₂CMe₃)]₂ and bipy give [W(NCMe₃)(NPh)Cl₂(bipy)] (6). ReOCl₄ reacts with PhNCO to give [Re(NPh)Cl₄]_x which in tetrahydrofuran (THF) or MeCN give the adducts [Re(NPh)Cl₄(THF)] and [Re(NPh)Cl₄(MeCN)]. [Re(NPh)Cl₄]_x reacts with Me₄NCl to give [Me₄N][Re(NPh)Cl₅], with PPh₃ to give [Re(NPh)Cl₃(PPh₃)₂] and with Me₃ SiNHCMe₃ gives [Re(NPh)Cl₃(NH₂CMe₃)₂] (12). The complexes were characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopy. The structures of [W(NCMe₃)(NPh)Cl₂(bipy)] (6) and [Re(NPh)Cl₃(NH₂CMe₃)₂] (12) were determined by single-crystal X-ray diffraction methods. Crystals of (6) are orthorhombic, space group P2₁2₁2₁, with a = 8.879(3) Å, b = 13.036(3) Å, c = 18.837(4) Å; crystals of (12) are orthorhombic, space group Pbcn with a = 14.140(1) Å, b = 11.806(1), Å, c = 11.936(3) Å. Both structures were solved by Patterson and Fourier methods and refined to R values of 0.053 for the 2138 observed data for (6) and 0.035 for the 1108 observed data for (12). In complex (6) the tungsten atom is in a distorted octahedral environment comprising cis-t-butylimido and phenylimido groups, trans chlorides and bidentate bipy. The bipy nitrogens lie trans to the imid o functions. Observed distances are: WN_phenylimido 1.774(8) Å, WN_t-butylimido 1.754(10) Å, WCl 2.412(3) and 2.390(3) Å and WN_bipy 2.312(10) Å and 2.333(9) Å. Interaction between the t-butylimido methyl groups and bipy is relieved by lengthening of one WN_bipy bond. In complex (12) the rhenium atom is in a distorted octahedral environment comprising three chloride ligands, two trans-t-butylamine ligands and a phenylimido ligand. Observed distances are: ReN_phenylimido 1.709(11) Å, ReN_t-butylamine 2.187(7) Å, and ReCl 2.404(2) and 2.411(5) Å. The complex attains an 18-electron count without π-bonding from the chloro ligands.     

Synthese von Nitrenkomplexen mit N-Trimethylsilylanilin. II. Charakterisierung und Kristallstruktur der Rhenium(V)-phenylnitren-Komplexe mer-[Re(NPh)Cl3(NH2Ph)(Ph3P)] und trans-[Re(NPh)(OMe)Cl2(Ph3P)2]

Synthesis of Phenylnitrene Complexes with N-Trimethylsilylaniline. II. Characterization and Crystal Structure of the Rhenium(V) Complexes mer-[Re(NPh)Cl₃(NH₂Ph)(Ph₃P)] and trans-[Re(NPh)(OMe)Cl₂(Ph₃P)₂] Reaction of [ReOCl₃(Ph₃P)₂] with N-trimethylsilylaniline yields mer-[Re(NPh)Cl₃(Ph₃P)₂], which reacts under air with excess of N-trimethylsilylaniline to form [Re(NPh)Cl₃ · (NH₂Ph)(Ph₃P)]. Crystallization from CH₂Cl₂/MeOH affords [Re(NPh)(OMe)Cl₂(Ph₃P)₂] as an additional product. [Re(NPh)Cl₃(NH₂Ph)(Ph₃P)] crystallizes in the monoclinic space group P2₁/n with a = 1 192.3(3); b = 1 918.9(3); c = 1 266.3(3) pm; β = 101.71(1)°; Z = 4. The rhenium atom has a distorted octahedral environment with the Cl atoms in meridional positions. The phenyl nitrene ligand is coordinated with an almost linear arrangement Re? N1? C40 = 166.8(6)° and with a bond distance Re?N = 170.5(6) pm. [Re(NPh)(OMe)Cl₂(Ph₃P)₂] · 1/2CH₂Cl₂ crystallizes in the triclinic space group P1 : a = 1 103.1(4); b = 1 227.9(4); c = 1 711.3(5) pm; α = 70.48(3)°; β = 72.71(3)°; γ = 80.03(3)°; Z = 2. The rhenium atom exhibits a distorted octahedral coordination with the Cl atoms and the phosphine ligands in trans positions. As a consequence of the competition of the nitrene ligand and the trans-coordinated methoxy group the Re?;N bond length is slightly lengthened to 173.2(7) pm, while the Re? O bond length of 193.4(6) pm is short. The bond angles Re? N? C70 and Re? O? C80 are 173.3(7)° and 139.1(7)°, respectively.     

Monodentate imido and bidentate aminophenolate coordination of 2-aminophenol in rhenium(V) complexes

Reactions of trans-[ReOCl₃(PPh₃)₂] and trans-[ReO(OEt)I₂(PPh₃)₂] with 2-aminophenol (H₂ap) in acetonitrile led to the formation of cis-[ReOCl₂(Hap)(PPh₃)] (1) and trans-[Re(ap)(Hap)I(PPh₃)₂]I (2), respectively. The X-ray crystal structures show that Hap is coordinated as a bidentate chelate via the neutral amino nitrogen and deprotonated phenolate oxygen, and ap is coordinated as a monodentate through the imido nitrogen. The complexes have been characterized by IR spectroscopy, NMR spectrometry and X-ray crystallography. The bite angle of the Hap chelate is 76.9(1)° and 76.0(1)° in 1 and 2, respectively.     

2,2′-dipyridylamine complexes of rhenium(V)

The reactivity of oxorhenium(V) precursors with the potentially N,N-donor ligand 2,2′-dipyridylamine (dpa) has been investigated. Reaction of a two-fold molar excess of dpa with trans-[ReO(OEt)Cl₂(PPh₃)₂] in ethanol led to the isolation of [ReOCl₂(OEt)(dpa)] (1). Spectroscopic measurements indicate that dpa is coordinated as a bidentate in the equatorial plane cis to the oxo group, with the ethoxide in the trans position. Treatment of trans-[ReOCl₃(PPh₃)₂] with a tenfold molar excess of dpa in ethanol at reflux yielded the trans-dioxo complex [ReO₂(dpa)₂]Cl (2), but with a twofold molar excess (μ-O)[{ReOCl₂(dpa)}₂] (3a) was isolated. The latter reaction with (n-Bu₄N)[ReOCl₄] as starting material in ethanol at room temperature led to a dark green product, also with the formulation (μ-O)[{ReOCl₂(dpa)}₂] (3b). These compounds were characterised by common spectroscopic techniques, and the crystal structures of 2·3H₂O, 3a and 3b·2DMSO were determined. The structure of 3b presents a nearly linear O=Re–O–Re=O group, with the two [ReOCl₂(dpa)] halves of the dimer rotated by 180.0° about the Re–O–Re fragment away from an eclipsed conformation. In 3a, the two halves are only rotated by 61.4°.     

Phenylimido Complexes of Technetium and Rhenium with Maleonitriledithiolate

[Tc(NPh)Cl₃(PPh₃)₂] or [Re(NPh)Cl₃(PPh₃)₂] react with two equivalents of Na₂mnt (mnt^2– = 1,2‐dicyanoethene‐1,2‐dithiolate) with formation of anionic complexes of the composition [M(NPh)(mnt)₂]^–. The products can be isolated as large red blocks of their AsPh₄⁺ salts. The complex anions contain square‐pyramidal coordinated metal atoms with the phenylimido ligands in apical positions. The M–N–C bonds are almost linear. A similar phenylimido complex with an additional amino group was synthesized from [Re(NC₆H₄‐4‐NH₂)Cl₃(PPh₃)₂]. The presence of such substituents may allow coupling of the metal complexes to biomolecules such as peptides, proteins, or sugars, provided the M=N bonds are sufficiently stable against hydrolysis.     

Monodentate imido coordination of 2-aminodiphenylamine to rhenium(V)

The complex trans-[Re(ada)Cl₃(PPh₃)₂] (H₂ada?=?2-aminodiphenylamine) was prepared from the reaction of trans-[ReOCl₃(PPh₃)₂] with H₂ada in acetonitrile. The ligand ada is coordinated to the rhenium(V) centre solely through a dianionic imido nitrogen, with distorted octahedral coordination geometry around the metal ion. Surprisingly, the Re–Cl bond trans to the Re=N bond is shorter than the two equatorial Re–Cl bonds. The Re?=?N–C bond angle of the phenylimido moiety equals 178.7(4)°.     

Aminobis(phenolate)s of imidomolybdenum(VI) and -tungsten(VI)

The reactions of trans-[MoO(ONO^Me)Cl₂] 1 (ONO^Me = methylamino-N,N-bis(2-methylene-4,6-dimethylphenolate) dianion) and trans-[MoO(ONO^tBu)Cl₂] 2 (ONO^tBu = methylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenolate) dianion) with PhNCO afforded new imido molybdenum complexes trans-[Mo(NPh)(ONO^Me)Cl₂] 3 and trans-[Mo(NPh)(ONO^tBu)Cl₂] 4, respectively. As analogous oxotungsten starting materials did not show similar reactivity, corresponding imido tungsten complexes were prepared by the reaction between [W(NPh)Cl₄] with aminobis(phenol)s. These reactions yielded cis- and trans-isomers of dichloro complexes [W(NPh)(ONO^Me)Cl₂] 5 and [W(NPh)(ONO^tBu)Cl₂] 6, respectively. The molecular structures of 4, cis-6 and trans-6 were verified by X-ray crystallography. Organosubstituted imido tungsten(VI) complex cis-[W(NPh)(ONO^tBu)Me₂] 7 was prepared by the transmetallation reaction of 6 (either cis or trans isomer) with methyl magnesium iodide.     

Synthesis and structural characterization of ruthenium complexes with 1-aryl-imidazole-2-thione

Treatment of [RuCl₂(PPh₃)₃] with 2 equiv. Himt^MPh (Himt^MPh?=?1-(4-methyl-phenyl)-imidazole-2-thione) in the presence of MeONa afforded cis-[Ru(κ ²-S,N-imt^MPh)₂(PPh₃)₂] (1), while interaction of [RuCl₂(PPh₃)₃] and 2 equiv. Himt^MPh in tetrahydrofuran (THF) without base gave [RuCl₂(κ ¹-S-Himt^MPh)₂(PPh₃)₂] (2). Treatment of [RuHCl(CO)(PPh₃)₃] with 1 equiv. Himt^MPh in THF gave [RuHCl(κ ¹-S-Himt^MPh)(CO)(PPh₃)₂] (3), whereas reaction of [RuHCl(CO)(PPh₃)₃] with 1 equiv. of the deprotonated [imt^MPh]^? or [imt^NPh]^? (imt^NPh?=?1-(4-nitro-phenyl)-2-mercaptoimidazolyl) gave [RuH(κ ²-S,N-imt^RPh)(CO)(PPh₃)₂] (R?=?M 4a, R?=?N 4b). The ruthenium hydride complexes 4a and 4b easily convert to their corresponding ruthenium chloride complexes [RuCl(κ ²-S,N-imt^MPh)(CO)(PPh₃)₂] (5a) and [RuCl(κ ²-S,N-imt^NPh)(CO)(PPh₃)₂] (5b), respectively, in refluxing CHCl₃ by chloride substitution of the RuH. Photolysis of 5a in CHCl₃ at room temperature afforded an oxidized product [RuCl₂(κ ²-S,N-imt^MPh)(PPh₃)₂] (6). Reaction of 6 with excess [imt^MPh]^? afforded 1. The molecular structures of 1·EtOH, 3·C₆H₁₄, 4b·0.25CH₃COCH₃, and 6·2CH₂Cl₂ have been determined by single-crystal X-ray crystallography.     

Synthesis and Reactivity of Structurally Analogous Phenylimido and Oxo Complexes of Rhenium(V) with N,N‐Dialkyl‐N′‐benzoylthioureas

[ReOCl₃(PPh₃)₂] and [Re(NPh)Br₃(PPh₃)₂] react at room temperature with equivalent amounts of N,N‐dialkyl‐N′‐benzoylthioureas (HR¹R²btu) in CH₂Cl₂ under formation of the rhenium(V) complexes [ReOCl₂(R¹R¹btu)(PPh₃)] and [Re(NPh)Br₂(R¹R²btu)(PPh₃)], respectively. The products are structurally analogous with the oxygen atoms of the benzoylthioureas binding in trans positions to the oxo or phenylimido ligands. Prolonged reaction times result in the reduction of the oxo compound by the released PPh₃ and the formation of rhenium(III) complexes of the composition [ReCl₂(PPh₃)₂(R¹R²btu)], while such a second reaction path is excluded for the phenylimido compound. Phenylimido species with more than one N,N‐dialkyl‐N′‐benzoylthioureato ligand could not be isolated, even when a large excess of HR¹R²btu was used during the reaction.     

Synthesis and structural characterization of cationic octahedral oxorhenium(V) complexes with bidentate imidazole derivatives

Cationic distorted octahedral complexes [ReOCl(OEt)(L)(PPh₃)]X {L = 2-(1-ethylaminomethyl)-1-methylimidazole (eami), 2-(1-methylaminomethyl)-1-methylimidazole (mami), 2-(1-ethylthiomethyl)-1-methylimidazole (etmi); X=ReO₄, PF₆} were prepared by reaction of trans-[ReOCl₃(PPh₃)₂] with a twofold molar excess of L in ethanol under anaerobic conditions. X-ray structure determinations of [ReOCl(OEt)(eami)(PPh₃)](ReO₄) (1a) and its etmi equivalent (3a) were performed. In 1a coordination of the chloride occurs trans to the imidazole nitrogen. However, in 3a the chloride is coordinated trans to the ethereal sulfur donor of etmi.     

Oxorhenium(V) complexes containing bidentate N,O-donor ligands of the pyridyl type

The reaction of equimolar quantities of trans-[ReOCl₃(PPh₃)₂] and 8-hydroxyquinoline (Hhqn) in benzene led to the isolation of the six-coordinate complex [ReOCl₂(hqn)(PPh₃)] (1). With 2-pyridine-ethanol (Hhep) the compound [ReOCl₂(hep)(PPh₃)] (2) was obtained. Both hqn and hep ligands act as monoanionic bidentate N,O-donor chelates. Although the two complexes are very similar, there are some significant differences in certain bond distances and angles in them. Both complexes contain the nearly linear trans O=Re–O axis, with this angle equal to 160.9(2)° and 167.8(1)° in 1 and 2, respectively.     

Reactions of [Re(NO)2(PR3)2][BArF 4] complexes with phenylacetylene

The reaction of [Re(NO)₂(PR₃)₂][BAr^F ₄] (R = cyclo-C₆H₁₃ (1a), Prⁱ (1b); [BAr^F ₄]^– = [B(3,5-(CF₃)₂C₆H₃)₄]) with phenylacetylene in the presence of a non-nucleophilic base, like 2,6-bis(tert-butyl)pyridine (BTBP) or Bu^tOK, affords the phenylethynyl complexes [Re(CCPh)(NO)₂(PR₃)₂] (R = cyclo-C₆H₁₃ (2a); Prⁱ (2b)) in moderate yields. In the absence of a base, complexes 1a and 1b are transformed into the compounds [Re(CCPh)(CH=C(Ph)ONH)(NO)(PR₃)₂][BAr^F ₄] (3a and 3b, respectively). The structure of complex 3a was confirmed by X-ray diffraction analysis. The latter reaction is proposed to be initiated by deprotonation of the terminal alkyne H atom by the bent nitrosyl ligand followed by the subsequent 1,3-dipolar addition of the ReN(H)O moiety to phenylacetylene.     

Ruthenium(II/IV) complexes with potentially tridentate Schiff base chelates containing the uracil moiety

Herein we report the synthesis and characterization of trans-[Ru^IICl₂(PPh₃)₃] with potentially tridentate Schiff bases derived from 5,6-diamino-1,3-dimethyl uracil (H₂ddd) and two 2-substituted aromatic aldehydes. In the diamagnetic ruthenium(II) complexes, trans-[RuCl(PPh₃)₂(Htdp)] (1) {H₂tdp = 5-((thiophen-3-yl)methyleneamino)-6-amino-1,3-dimethyluracil} and trans-[RuCl(PPh₃)₂(Hsdp)] (2) {H₂sdp = 5-(2-(methylthio)benzylideneamino)-6-amino-1,3-dimethyluracil}, the Schiff base ligands (i.e. Htdp and Hsdp) act as mono-anionic tridentate chelators. Upon reacting 5-(2-hydroxybenzylideneamino)-6-amino-1,3-dimethyluracil (H₃hdp) with the metal precursor, the paramagnetic complex, trans-[Ru^IVCl₂(ddd)(PPh₃)₂] (3), was isolated, in which the bidentate dianionic ddd co-ligand was formed by hydrolysis. The metal complexes were fully characterized via multinuclear NMR-, IR-, and UV–Vis spectroscopy, single crystal XRD analysis and conductivity measurements. The redox properties were probed via cyclic voltammetry with all complexes exhibiting comparable electrochemical behavior with half-wave potentials (E_½) at 0.70 V (for 1), 0.725 V (for 2), and 0.68 V (for 3) versus Ag|AgCl, respectively. The presence of the paramagnetic metal center for 3 was confirmed by ESR spectroscopy.     

Reactivity of [ReOX3(PPh3)2] and [ReOX3(AsPh3)2] towards 2-(2-hydroxyphenyl)-1H-benzimidazole: Synthesis, X-ray studies, spectroscopic characterization and DFT calculations for [ReOX2(hpb)(EPh3)] and [ReO(OMe)(hpb)2]·MeCN

The paper presents a combined experimental and computational study of mono- and disubstituted Re(V) oxocomplexes obtained in the reactions of [ReOX₃(EPh₃)₂] (X = Cl, Br; E = P, As) with 2-(2-hydroxyphenyl)-1H-benzimidazole (Hhpb). From the reactions of [ReOX₃(PPh₃)₂] with Hhpb in molar ratio 1:1 cis and trans stereoisomers of [ReOX₂(hpb)(PPh₃)] were isolated, whereas the [ReOX₃(AsPh₃)₂] oxocompounds react with Hhpb to give only cis-halide isomers. The [ReOX₂(hpb)(EPh₃)] and [ReO(OMe)(hpb)₂]·MeCN complexes have been characterized spectroscopically and structurally (by single-crystal X-ray diffraction). The DFT and TDDFT calculations have been carried out for the trans-[ReOBr₂(hpb)(PPh₃)], cis-[ReOBr₂(hpb)(AsPh₃)] and [ReO(OMe)(hpb)₂], and their UV–Vis spectra have been discussed on this basis.     

PREPARATION AND PROPERTIES OF DIAZENIDO,HYDRAZIDO(2-), AND HYDRIDO-HYDRAZIDO(2-) COMPLEXES OF TUNGSTEN. X-RAY PHOTOELECTRON SPECTROSCOPY OF DINITROGEN AND HYDRAZIDO(2-) COMPLEXES OF MOLYBDENUM AND TUNGSTEN

Abstract

Reactions of HBr with trans-[W(N₂)₂(dppe)PPh₂Me)₂] (1) (dppe = Ph₂CH₂CH₂PPh₂) result in protonation of coordinated N₂ but no formation of ammonia or hydrazine. The tungsten-containing product depends upon the reaction conditions: (i) in MeOH, the product formed is [WBr(NNH₂) (dppe)(PPh₂Me)₂]HBr₂ (2) which converts to the hydride, [WBr₂(H)(NNH₂(dppe)(PPh₂Me)](Br(3), with loss of phosphine in THF or CH₂Cl₂, (ii) in THF or CH₂Cl₂, the hydride (3) is formed directly. Reaction of 2 with Na₂CO₃ in MeOH results in the loss of HBr and the formation of the diazenido complex [WBr(NNH)(dppe)(PPh₂Me)₂] which reacts further with Na₂CO₃ in benzene under N₂ to lose HBr and form a mixture of 1 and trans-[W(N₂)(dppe)₂]. The reaction of 1 with aqueous HF forms [WF(NNH₂)(dppe)(PPh₂Me)₂]BF₄. The X-ray photoelectron spectra of trans-[M(N₂)₂ (dppe)₂], [MBr(NNH₂)(dppe)₂Br (M = Mo, W), [WCl(NNH₂)(dppe)₂]Cl, [WCl(N)(dppe)₂]Cl and [WCl(NH) (dppe)₂] are reported. In all of these complexes, nitrogen is in a highly reduced form.     

Monodentate imido coordination of 1,2-diaminobenzene to rhenium(V)

The complex trans-[Re(dab)Cl₃(PPh₃)₂] (H₂dab?=?1,2-diaminobenzene) was prepared from the reaction of trans-[ReOCl₃(PPh₃)₂] with H₂dab in ethanol. The ligand dab is coordinated to the rhenium(V) centre only through a dianionic imido nitrogen to give a distorted octahedral coordination geometry around the metal ion.     

Synthesis,spectroscopic investigation,structural characterization,and DFT calculations of [ReX2(N2COPh)(CH3PhCN)(PPh3)2] (X=Cl,Br)

Reactions of [ReX₂(η ²-N₂COPh-N′,O)(PPh₃)₂] with 3-methylbenzonitrile give two iso-structural complexes, [ReX₂(N₂COPh)(CH₃PhCN)(PPh₃)₂] (X?=?Cl, Br). The crystal and molecular structures of [ReCl₂(N₂COPh)(CH₃PhCN)(PPh₃)₂] (1) and [ReBr₂(N₂COPh)(CH₃PhCN)(PPh₃)₂]?·?CH₂Cl₂ (2) were determined. The electronic structures were examined with density functional theory (DFT). The spin-allowed electronic transitions were calculated with the time-dependent DFT method, and the UV-Vis spectrum has been discussed.     

Synthesis,Spectroscopy, and Structures of Mono‐ and Dinuclear Copper(I) Halide Complexes with 1,3‐Imidazolidine‐2‐thiones

Copper(I) halides with triphenyl phosphine and imidaozlidine‐2‐thiones (L ‐NMe, L ‐NEt, and L ‐NPh) in acetonitrile/methanol (or dichloromethane) yielded copper(I) mixed‐ligand complexes: mononuclear, namely, [CuCl(κ¹‐S‐L ‐NMe)(PPh₃)₂] ( 1 ), [CuBr(κ¹‐S‐L ‐NMe)(PPh₃)₂] ( 2 ), [CuBr(κ¹‐S‐L ‐NEt)(PPh₃)₂] ( 5 ), [CuI(κ¹‐S‐L ‐NEt)(PPh₃)₂] ( 6 ), [CuCl(κ¹‐S‐L ‐NPh)(PPh₃)₂] ( 7 ), and [CuBr(κ¹‐S‐L ‐NPh)(PPh₃)₂] ( 8 ), and dinuclear, [Cu₂(κ¹‐I)₂(μ‐S‐L ‐NMe)₂(PPh₃)₂] ( 3 ) and [Cu₂(μ‐Cl)₂(κ¹‐S‐L ‐NEt)₂(PPh₃)₂] ( 4 ). All complexes were characterized with analytical data, IR and NMR spectroscopy, and X‐ray crystallography. Complexes 2 – 4 , 7 , and 8 each formed crystals in the triclinic system with P$\bar{1}$ space group, whereas complexes 1 , 5 , and 6 crystallized in the monoclinic crystal system with space groups P2₁/c, C2/c, and P2₁/n, respectively. Complex 2 has shown two independent molecules, [(CuBr(κ¹‐S‐L ‐NMe)(PPh₃)₂] and [CuBr(PPh₃)₂] in the unit cell. For X = Cl, the thio‐ligand bonded to metal as terminal in complex 4 , whereas for X = I it is sulfur‐bridged in complex 3 .