Heterocyclic thioamides of copper(I): Synthesis and crystal structures of copper complexes with 1,3-imidazoline-2-thiones in the presence of triphenyl phosphine

Reaction of copper(I) chloride with 1,3-imidazoline-2-thione (imzSH) in the presence of Ph₃P in 1:2:2 or 1:1:2 (M:L:PPh₃) molar ratios yielded a compound of unusual composition, [Cu₂(imzSH)(PPh₃)₄Cl₂] · CH₃OH (1), whose X-ray crystallography has shown that its crystals consist of four coordinated [CuCl(1κS-imzSH)(PPh₃)₂] (1a), and three coordinated [Cu(PPh₃)₂Cl] (1b) independent molecules in the same unit cell. In contrast, crystals of complexes of copper(I) bromide/iodide are formed by single molecules of [CuBr(1κS-imzSH)(PPh₃)₂] · H₂O (2) and [CuI(1κS-imzSH)(PPh₃)₂] (3), respectively, similar to molecule 1a. The related ligand, 1,3-benzimidazoline-2-thione (bzimSH) formed a complex [CuBr(1κS-bzimSH)(PPh₃)₂] · CH₃COCH₃ (4), similar to 2. The formation of 1a and 1b has been also revealed by NMR spectroscopy. The NMR spectra of 2–4 also showed weak signals indicating formation of compounds similar to 1b. It reveals that the lability of the Cu–S bond varies in the order: Cl ? Br ∼ I. Weak interactions {e.g. C–H?π electrons of ring, –NH?halogens/oxygen, C–H?halogens/oxygen, π?π (between rings)} have played an important role in building 2D chains of complexes 1–4.     

Mono- and bis-(2-dimethylaminoethyl)tetramethylcyclopentadienyl zirconium(IV) complexes: synthesis and structural studies in crystalline state and in solutions

A novel half-sandwich Zr(IV) complex [η⁵:η¹-N-C₅(CH₃)₄CH₂CH₂N(CH₃)₂]ZrCl₃ (6) together with zirconocene dichlorides [η⁵-C₅(CH₃)₄CH₂CH₂N(CH₃)₂][η⁵-C₅(CH₃)₅]ZrCl₂ (4) and [η⁵-C₅(CH₃)₄CH₂CH₂N(CH₃)₂]₂ZrCl₂ (5) have been prepared. Complex 6 has been isolated and characterized in three different forms, namely, as an adduct with THF 6a, an adduct with tetrahydrothiophene 6b, and a solvent-free form 6c. Molecular structures of complexes 4, 6b, and 6c have been established by X-ray diffraction analysis. Complex 6c has been shown to be a monomeric solvent-free half sandwich Zr(IV) complex. The dynamic behavior of complex 6a in a non-solvating medium (an equilibrium between 6a and 6c along with a degenerate interconversion of the Zr-C_cp-CH₂-CH₂-N(CH₃)₂-(Zr) pseudo-five-member metallacycle) have been studied by the variable-temperature ¹H and ¹³C{¹H} NMR spectroscopy. The activation parameters for the degenerate five-member cycle interconversion have been elucidated.     

New photochromic chemosensors for Hg and F

Two new chemosensors (1a and 1b) based on photochromic dithienylcyclopentene were designed and synthesized, and their spectral behaviors toward various metal ions and anions were investigated in detail. Compounds show excellent optical properties and distinguish Hg²⁺ and F⁻ in CH₃CN. Job’s plot reveals that the presence of Hg²⁺ induces the formation of a 1:1 complex between 1a or 1b and Hg²⁺. From the spectral responses and ¹H NMR analysis, the deprotonation of the thioamide protons is proposed to explain the sensing mechanism for 1a and 1b toward F⁻. It is found that 1a and 1b exhibit ring-opening and ring-closing photoisomerization with UV-vis light irradiation. Furthermore, their photochromic properties can be modulated by Hg²⁺ and F⁻ ions. Moreover, 1a and 1b in photostationary states become promising sensors for Hg²⁺ and F⁻ with high selectivity.     

Syntheses, structures and catalytic activity of copper(II) complexes with hydroxyindanimine ligands

A series of new hydroxyindanimine ligands [ArNCC₂H₃(CH₃)C₆H₂(R)OH] (Ar = 2,6-i-Pr₂C₆H₃, R = H (HL¹), R = Cl (HL²), and R = Me (HL³)) were synthesized and characterized. Reaction of hydroxyindanimine with Cu(OAc)₂ · H₂O results in the formation of the mononuclear bis(hydroxyindaniminato)copper(II) complexes Cu[ArNCC₂H₃(CH₃)C₆H₂(R)O]₂ (Ar = 2,6-i-Pr₂C₆H₃, R = H (1), R = Cl (2), and R = Me (3)). The complex 2′ was obtained from the chlorobenzene solution of the complex 2, which has the same molecule formula with the complex 2 but it is a polymorph. All copper(II) complexes were characterized by their IR and elemental analyses. In addition, X-ray structure analyses were performed for complexes 1, 2, and 2′. After being activated with methylaluminoxane (MAO), complexes 1-3 can be used as catalysts for the vinyl polymerization of norbornene with moderate catalytic activities. Catalytic activities and the molecular weight of polynorbornene have been investigated for various reaction conditions.     

Syntheses and crystal structures of manganese,nickel and zinc chloride complexes with dimethoxyethane and di(2-methoxyethyl) ether

Reactions of manganese and zinc chloride with dimethoxyethane (DME) in the presence of (CH₃)₃SiCl and water resulted in [MnCl₂(DME)]_n (1) with a polymeric chain structure and in the molecular [ZnCl₂(DME)]₂ (2), respectively. The complexes 1 and 2 reacted with di(2-methoxyethyl) ether (abbreviated diglyme) in tetrahydrofuran (THF) solvent achieving binuclear [MnCl₂(diglyme)]₂ (3) and mononuclear [ZnCl₂(diglyme)] (4), respectively. The complex [NiCl₂(diglyme)]₂ (5) was prepared by the reaction of nickel chloride hexahydrate, diglyme and (CH₃)₃SiCl in THF solvent. A distorted octahedral geometry was found for manganese and nickel ions in the complexes 1, 3 and 5. Linear chains of manganese ions linked by double chloride bridges are present in 1. Two bridging chlorides connect two manganese or nickel atoms into isostructural binuclear molecules 3 and 5, respectively. Two zinc ions in the complex 2 are in different environments, in a tetrahedral and in an octahedral one, while five-coordinate zinc ions are present in the mononuclear complexes 4.     

Syntheses, structures and electrochemistry of some 1-(η-allylamino)-1-ferrocenylcarbene complexes of chromium(0), molybdenum(0) and tungsten(0) : Part 13: The chemistry of metallacyclic alkenylcarbene complexes

The metallacyclic complexes (OC)₄MC(η²-NHCH₂CHCHX)Fc (4; X = H) and (5; X = CH₂OH) [M = Cr: a; Mo: b; W: c; Fc = ferrocenyl = CpFe(C₅H₄)] were obtained in good yields upon photo-decarbonylation of the bimetallic allylaminocarbene complexes (OC)₅MC(NHCH₂CHCHX)Fc (2; X = H)/(3; X = CH₂OH). At room temperature complexes 2/3 exist as mixtures of E- and predominantly Z-isomers with regard to the C-N bond. The molecular structures of 4b and 4c were determined by X-ray diffraction analyses. The intermetallic communicative effects and the interplay of Fc and η²-alkene moieties of 4a and 4b were assessed by cyclovoltammetry. All complexes were also characterized in solution by one- and two-dimensional NMR spectroscopy (¹H, ¹³C, ¹H NOE, ¹H/¹H COSY, ¹³C/¹H HETCOR).     

Assembly of cyano-bridged Cu(II)/Cu(II) and Cu(I)/Cu(II) compounds obtained by controlled ration of cyanide

One reaction system of Cu²⁺, dipn, and CN⁻ with two different molar ratio sets of 1:1:5, and 2:1:8 produced two compounds 1 [Cu^II(dipn)][Cu^II(CN)₄], and 2, respectively (dipn = dipropylenetriamine). Their structures were determined by X-ray crystallography. Compound 2 is built from Cu(I) and Cu(II) centers, which are bridged by cyanide groups and metal-metal bonds. The magnetic properties of 1 and 2 were investigated in 2-300 K. Compound 1 exhibits an antiferromagnetic exchange interaction between copper(II) ions mediated by cyano-bridges.     

Preparation,NMR studies and crystal structure of mononuclear and dinuclear Pd(II) and Pt(II) complexes that contain 1,2-bis[3-(3,5-dimethyl-1-pyrazolyl)-2-thiapropyl]benzene

The reaction between 1,2-bis[3-(3,5-dimethyl-1-pyrazolyl)-2-thiapropyl]benzene (bddf) and [MCl₂(CH₃CN)₂] (M = Pd(II), Pt(II)) in a 1:1 M/L ratio in CH₂Cl₂ or acetonitrile solution, respectively, gave the complexes trans-[MCl₂(bddf)] (M = Pd(II) (1), Pt(II) (4)), and in a 2:1 M/L ratio led to [M₂Cl₄(bddf)] (M = Pd(II) (2), Pt(II) (5)). Treatment of 1 and 4 with AgBF₄ and NaBPh₄, respectively, gave the compounds [Pd(bddf)](BF₄)₂ (3) and [Pt(bddf)](BPh₄)₂ (6). When complexes 3 and 6 were heated under reflux in a solution of Et₄NBr in CH₂Cl₂/CH₃OH (1:1) for 24 h, analogous complexes to 1 and 4 with bromides instead of chlorides bonded to the metallic centre were obtained. These complexes were characterised by elemental analyses, conductivity measurements, infrared, ¹H, ¹H{¹⁹⁵Pt}, ¹³C{¹H}, ¹⁹⁵Pt{¹H} NMR, HSQC and NOESY spectroscopies. The X-ray crystal structure of the complex [Pd(bddf)](BF₄)₂ · H₂O has been determined. The metal atom is tetracoordinated by the two azine nitrogen atoms of the pyrazole rings and two thioether groups.     

Syntheses and crystal structures of a series of new divalent metal phosphonates with imino-bis(methylphosphonic acid)

Hydrothermal reactions of divalent transition metal salts with imino-bis(methylphosphonic acid), NH(CH₂PO₃H₂)₂ (H₄L) afforded three new metal phosphonates, namely, Cu[NH(CH₂PO₃H)₂] 1, {Co[NH₂(CH₂PO₃H)(CH₂PO₃)](H₂O)₂}·H₂O 2 and Mn[NH₂(CH₂PO₃H)(CH₂PO₃)](H₂O) 3. When HO₂C(CH₂)₃N(CH₂PO₃H₂)₂ was used as the phosphonate ligand and 4,4′-bipy as the second metal linker, {Cu₄[NH(CH₂PO₃)₂]₂(4,4′-bipy)(H₂O)₄}·9H₂O 4 with a pillared layered architecture was obtained. The NH(CH₂PO₃)₂ anion resulted from the cleavage of the HO₂C(CH₂)₃-group during the reaction. Although compounds 1-3 have a same M/L ratio (1:1), they exhibit totally different structures.Compound 1 has a linear chain structure, in which each pair of square-pyramidal coordinated copper(II) ions are bridged by two phosphonate oxygen atoms to form a Cu₂O₂ dimeric unit, and such dimeric units are further interconnected via phosphonate groups to form a [010] chain. Compound 2 has a layered architecture built from CoO₆ octahedra bridged by phosphonate ligands. In compound 3, the interconnection of the manganese(II) ions by bridging imino-diphosphonate ligands leads to a 3D network. Compound 4 has a pillar-layered structure, the layers composed of Cu(II) ions bridged by aminodiphosphonate ligands are interconnected by 4,4′-bipy ligands to form channels along c-axis. Several factors that affect the structures of the metal phosphonates formed have also been discussed. Compounds 2 and 3 show predominant antiferromagnetic interactions between magnetic centers.     

Crystal structures of amarine and isoamarine and copper(I) coordination chemistry with their allylation products

The crystal structures of amarine (1) and isoamarine (2), important intermediates in the preparation of 1,2-diphenyl-diaminoethane, were successfully determined. Their allylation products, 1,3-diallyl amarine (1)(CH₂CHCH₂)₂Br (3) and isoamarine bromide (2)(CH₂CHCH₂)₂Br (4) [the crystal structures of (1)(CH₂CHCH₂)₂PF₆(3-Br + PF₆) and (2)(CH₂CHCH₂)₂PF₆ (4-Br + PF₆) are also successfully determined to confirm allylation products], react with CuBr to afford (1)₂(CH₂CHCH₂)₄(Cu₂Br₄) (5) and (2)(CH₂CHCH₂)₂(Cu₂Br₃) (6), respectively. Crystal structures of 5 and 6 reveal that 5 is an anion discrete complex without olefin moiety coordination, and 6 has a 1D infinite chain with olefin moiety coordination as a bridging spacer. The fluorescent emission spectra of 5 (λ_emax = 570 nm) and 6 (λ_emax = 642 nm) were measured, and display a significant difference that can be used for solid state fluorescent sensing them.     

Unusual reactivity of 3-chloro-1-pentafluorosulfanylpropene in nucleophilic substitution reactions

Treatment of 3-chloro-1-pentafluorosulfanylprop-1-ene 1 with KCN yielded the product of prototropic rearrangement ClCHCHCH₂SF₅, whereas reactions with NaN₃ and KSCN gave the S_N2 products. Ab initio calculations at MP2/6-311++G** level are used to explain the unusual behaviour of cyanide. It was found that proton transfers from both 1 to CN⁻ and from HCN to the anion of 1 are exothermic. In contrast, azide and thiocyanate ions are too weakly basic to deprotonate 1.     

C-C bond formation by cyanide addition to dinuclear vinyliminium complexes

The diiron vinyliminium complexes [Fe₂{μ-η¹:η³-C(R′)C(H)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R=Me, R′ = SiMe₃ (1a); R = Me, R′ = CH₂OH (1b); R = CH₂Ph, R′ = Tol (1c), Tol = 4-MeC₆H₄; R = CH₂Ph, R′ = COOMe (1d); R = CH₂Ph, R′ = SiMe₃ (1e)) undergo regio- and stereo-selective addition by cyanide ion (from ), affording the corresponding bridging cyano-functionalized allylidene compounds [Fe₂{μ-η¹:η³-C(R′)C(H)C(CN)N(Me)(R)}(μ-CO)(CO)(Cp)₂] (3a-e), in good yields. Similarly, the diiron vinyliminium complexes [Fe₂{μ-η¹:η³-C(R′)C(R′)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R = R′ = Me (2a); R = Me, R′ = Ph (2b); R = CH₂Ph, R′ = Me (2c); R = CH₂Ph, R′ = COOMe (2d)) react with cyanide and yield [Fe₂{μ-η¹:η³-C(R′)C(R′)C(CN)N(Me)(R)}(μ-CO)(CO)(Cp)₂] (9a-d). The reactions of the vinyliminium complex [Fe₂{μ-η¹:η³-C(Tol)CHCN(Me)(4-C₆H₄CF₃)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (4) with NaBH₄ and afford the allylidene [Fe₂{μ-C(Tol)C(H)C(H)N(Me)(C₆H₄CF₃)}(μ-CO)(CO)(Cp)₂] (5) and the cyanoallylidene [Fe₂{μ-C(Tol)C(H)C(CN)N(Me)(C₆H₄CF₃)}(μ-CO)(CO)(Cp)₂] (6), respectively. Analogously, the diruthenium vinyliminium complex [Ru₂{μ-η¹:η³-C(SiMe₃)CHCN(Me)(CH₂Ph)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (7) reacts with to give [Ru₂{μ-η¹:η³-C(SiMe₃)CHC(CN)N(Me)(CH₂Ph)}(μ-CO)(CO)(Cp)₂] (8).Finally, cyanide addition to [Fe₂{μ-η¹:η³-C(COOMe)C(COOMe)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (2e) (Xyl = 2,6-Me₂C₆H₃), yields the cyano-functionalized bis-alkylidene complex [Fe₂{μ-η¹:η²-C(COOMe)C(COOMe)(CN)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)₂] (10). The molecular structures of 3a and 9a have been elucidated by X-ray diffraction.     

Palladium complexes containing ligands with hydrogen-bonding functionalities. Reactivity and catalytic studies with CO and olefins

The synthesis of the new bidentate N-N ligand 1-(2-(1-(pyridin-2-yl)ethylideneamino)ethyl)-3-ethylurea (PyUr) with a urea substituent attached to the imine nitrogen is reported. This ligand has been used to form palladium complexes and study the potential influence of the urea group (as a hydrogen bonding unit and a hemilabile ligand) in the insertion of CO and olefins into Pd-C bonds. The reaction of PyUr with [Pd(CH₃)(Cl)(COD)] to yield [Pd(CH₃)Cl(PyUr)] (1) is reported. A crystallographic study of this complex was carried out showing that the urea moieties are involved in a series of intermolecular hydrogen bonding interactions. Upon removal of the chloride from the coordination sphere of 1 (by addition of AgBF₄) the urea group of PyUr coordinates to the palladium centre stabilizing an otherwise coordinatively unsaturated complex. The reaction of these complexes with CO to yield [Pd{C(O)CH₃}Cl(PyUr)] (3) and [Pd{C(O)CH₃}(PyUr)][BF₄] (4) is also discussed. Following on from these reactions, the copolymerization of CO and styrene using 1 as a catalyst was studied and is herein reported. The copolymers synthesized using 1 as a catalyst were obtained in moderate yields and showed to have a narrow size distribution. The same reaction was performed using a palladium complex coordinated by an analogous pyridine ligand but without a hydrogen bonding substituent. The results of the copolymerization reactions showed that, although slightly better yields and larger molecular weights were obtained with the PyUr-containing catalyst, the hydrogen bonding groups in PyUr have little influence on the course of the reaction. To explore further the reactivity of the palladium complexes, the reaction between [Pd(CH₃)Cl(PyUr)][BF₄] (2) and CH₂CHCH₂OH was carried out to yield the allyl complex [Pd(η³-CH₂CHCH₂)(PyUr)] (6). The crystal structure of this complex is also reported.     

Synthesis and characterization of water-soluble palladium(II)-functionalized diphosphine complexes

Water-soluble functionalized bis(phosphine) ligands L (a–h) of the general formula CH₂(CH₂PR₂)₂, where for a: R = (CH₂)₆OH; b–g: R = (CH₂)_nP(O)(OEt)₂, n = 2–6 and n = 8; h: R = (CH₂)₃NH₂ ( Scheme 1), have been prepared photochemically by hydrophosphination of the corresponding 1-alkenes with H₂P(CH₂)₃PH₂. Water-soluble palladium complexes cis-[Pd(L)(OAc)₂] (1–8) were obtained by the reaction of Pd(OAc)₂ with the ligands a–h in a 1:1 mixture of dichloromethane:acetonitrile. The water-soluble phosphine ligands and their palladium complexes were characterized by IR, ¹H and ³¹P NMR. A crystallographic study of complex 1 shows that the Pd(II) ion has a square planar coordination sphere in which the acetate ligands and the diphosphine ligand deviate by less than 0.12 Å from ideal planar.     

Synthesis,structure, network and thermal analysis of four 5-(pyrazinyl)tetrazolato copper(II) and cobalt(II) complexes

Three new copper complexes and one cobalt complex with 5-(pyrazinyl)tetrazolate anion, (pyztz)⁻, as chelating bidentate ligand, were obtained by the reaction of pyrazinecarbonitrile with sodium azide in the presence of copper(II) nitrate or cobalt(II)chloride. Complexes of composition [Cu(pyztz)₂(H₂O)] (1) deep blue crystals, [Cu(pyztz)₂(H₂O)₂] (2a) green crystals, [Co(pyztz)₂(H₂O)₂] (2b) orange crystals, [Cu(pyztz)₂(H₂O)₂] · (H₂O) (3) blue crystals were obtained. The single crystal X-ray diffraction revealed that complex 1 has square pyramidal structure with one water molecule at apical and two pyrazine-tetrazolato ligands at basal sites, while structures of 2a, 2b and 3 consist of octahedrally coordinated metal ions, where two pyztz anions act as bidentate ligands via one of the pyrazine-N atoms and one of the tetrazole-N atoms in trans-positions and two trans water molecules. Complex 3 contains one extra lattice water molecule. Hydrogen bonds of the types O–H?O and O–H?N connect the mononuclear units to a three-dimensional network structure in 2 (a and b are isostructural) and 3. Although the H-bond patterns look complex it is shown that they can be related to the well-known three- and six-connected rutile net (rtl) in 2 and the four- and six-connected fsh-net in 3.     

ipso-and para-Functionalization of meta-terphenyl ligands with substituted methyl groups: Unusual head-to-tail coupling of terphenyl moieties

The synthesis and characterization of several ipso-functionalized derivatives of the bulky terphenyl group are described. These include the primary alcohol Ar′CH₂OH (1), the bromo derivative Ar′CH₂Br (2), and the terphenyl formate Ar′CH₂OC(O)H (3). The alcohol 1 was obtained by treatment of LiAr′ with formaldehyde, and 1 was readily converted to the bromo derivative 2 using HBr. The reaction of 1 with formic acid afforded 3 in good yield. Attempts to form the Grignard derivative of 1, i.e., Ar′CH₂MgBr, resulted in a head-to-tail reaction of the terphenyl benzyl units to yield an unusual coupled product 4. An approach to the avoidance of this coupling involved the synthesis of the terphenyl derivatives and , bearing methyl groups in the para positions of the central aryl ring, which could be prepared in good yield, and converted to their respective lithium salts 7 and 8 without complication . The compounds were characterized by ¹H and ¹³C NMR spectroscopy, IR spectroscopy (1) and X-ray crystallography (2, 4, 5 and 6).     

Synthesis and reactivity of ruthenium tetrazolate complexes containing a tris(pyrazolyl)borato (Tp) ligand

Facile ligand substitutions are observed when the neutral ruthenium cyclopropenyl complex (PPh₃)[Ru]-CC(Ph)CHCN (1, [Ru] = Tp(PPh₃)Ru) is treated with MeCN and pyrazole yielding the nitrile substituted ruthenium cyclopropenyl complex (MeCN)[Ru]-CC(Ph)CHCN (4a) and the ruthenium metallacyclic pyrazole complex (C₃H₃NN)[Ru]-CC(Ph)CH₂CN (7a), respectively. The reactions of Me₃SiN₃ with 1, 4a and 7a are investigated. Treatment of 1 with Me₃SiN₃ affords in high yield the cationic N-coordinated nitrile complex {(PPh₃)[Ru]NCCH(Ph)CH₂CN}N₃ (3). Interestingly, the reaction of 4a with Me₃SiN₃ in CH₂Cl₂ in the presence of NH₄PF₆ results in an insertion of four nitrogen atoms into the Ru-C_α bond to form a diastereomeric mixture of the bright yellow zwitterionic tetrazolate complex (MeCN)[Ru]-N₄CCH(Ph)CH₂CN (6a) in a 3:2 ratio. The reaction of 7a with Me₃SiN₃ gives the zwitterionic tetrazolate complex (C₃H₃NNH)[Ru]-N₄CCH(Ph)CH₂CN (9a). The two cationic tetrazolate complexes {(C₃H₃NNH)[Ru]-N₄(R)CCH(Ph)CH₂CN}⁺ (12a, R = CH₃, 12b, R = C₆H₅CH₂) are prepared by electrophilic addition of organic halides to 9a. All of the complexes are identified by spectroscopic methods as well as elemental analysis. Pathways for the synthesis of these compounds are proposed.     

Trinuclear copper(I) acetylide complexes bearing carbonyl moiety: Synthesis, characterization, and photophysical properties

A series of trinuclear copper(I) acetylide complexes with carbonyl moiety, [Cu₃(μ-dppm)₃(μ₃-η¹-CCC(O)R)₂](ClO₄) (R = H (1), CH₃ (2), OCH₃ (3), NH₂ (4), NEt₂ (5)) (dppm = bis(diphenylphosphino)methane), have been synthesized and characterized. The crystal structures of [Cu₃(μ-dppm)₃(μ₃-η¹-CCC(O)CH₃)₂](ClO₄) (2) and [Cu₃(μ-dppm)₃(μ₃-η¹-CCC(O)NH₂)₂](ClO₄) (4) were determined by X-ray diffraction. The photophysical properties of complexes 1−5 have been studied. Complexes 1−5 show luminescence both in the solid state and in acetonitrile solution at 298 K, and their emission energies are in the order: 5 > 4 > 3 > 2 > 1. Density function theory (DFT) calculations at the hybrid Perdew, Burke, and Ernzerhof functional (PBE1PBE) level were performed on model complex 1 to elucidate the emission origin of complexes 1−5.     

Water soluble phosphine rhenium complexes

Reduction of [NMe₄]₂[ReBr₅(NO)] (1) with zinc in acetonitrile leads to the known trisacetonitrile compound [ReBr₂(CH₃CN)₃(NO)] (2). Attempts to turn 2 into a dihydrogen or a hydride complex applying direct reaction with H₂ or with H₂ and a base were unsuccessful. Complex 2 could be transformed into [ReBr(BF₄)mer-(CH₃CN)₃(NO)] (2a) with AgBF₄ in acetonitrile and was used as a starting material in a ligand exchange reaction with the water soluble phosphine 1,3,5-triaza-7-phosphadamantane (PTA) to obtain the complex [ReBr₂(NO)(PTA)₃] (3). When the reduction of 1 with zinc was carried out in the presence of PTA in acetonitrile, the disubstituted complex [ReBr₂(CH₃CN)(NO)(PTA)₂] (4) was formed. The olefin-coordinated rhenium complexes [ReBr₂(NO)(CH₂CH₂)(PTA)₂] (5a) and [ReBr₂(NO)(PhCHCH₂)(PTA)₂] (5b) were obtained from the reaction of 4 with the corresponding olefins. Complex 4 reacts further with NaHBEt₃ in THF to give the dihydride [ReH₂(THF)(NO)(PTA)₂] (6). In the presence of ethylene 6 is transformed into the ethyl hydride complex [ReH(CH₂CH₃)(η²-C₂H₄)(NO)(PTA)₂] (7). Complexes 6 showed catalytic activity in the hydrogenation of olefins.