Synthesis, structures, photoluminescent and electroluminescent properties of boron complexes with anilido-imine ligands

Syntheses of three new N-arylanilido-arylimine bidentate Schiff base type ligand precursors, ortho-C₆H₄[NH(2,6-ⁱPr₂C₆H₃)](CHNAr¹) [Ar¹ = p-FC₆H₄ (2a); C₆H₅ (2b); p-OMeC₆H₄ (2c)], and their four-coordinated boron complexes, ortho-C₆H₄[N(2,6-ⁱPr₂C₆H₃)](CHNAr¹)BF₂ [Ar¹ = p-FC₆H₄ (3a); C₆H₅ (3b); p-OMeC₆H₄ (3c)] are described. The boron complexes 3a-3c were synthesized from the reaction of BF₃(OEt₂) with the lithium salt of their corresponding ligand. All complexes were characterized by ¹H and ¹³C NMR spectroscopy and molecular structures of complexes 3a and 3c were determined by X-ray crystallography. The photophysical properties of complexes 3a-3c were briefly examined. All three complexes display bright green fluorescence in solution and in the solid state. Electroluminescent devices with complex 3c as the emitter were fabricated. These devices were found to give green emission with maximum current efficiency of 2.92 cd/A and maximum luminance of 670 cd/m².     

Synthesis, spectral and structural studies of water soluble arene ruthenium (II) complexes containing 2,2′-dipyridyl-N-alkylimine ligand

A series of water soluble complexes of general formula [(η⁶-arene)Ru{(C₅H₄N)₂CNRi}Cl]PF₆ have been prepared by the reaction of [{(η⁶-arene)RuCl₂}₂] with appropriate 2,2′-dipyridyl-N-alkylimine ligands (dpNRi) in the presence of NH₄PF₆ (where; R = Me or Et; arene = p-cymene, C₆Me₆, C₆H₆). The 2,2′-dipyridyl-N-alkylimine ligands are prepared by reaction of 2,2′-dipyridyl ketone with the corresponding alkylamine. The complexes are readily obtained as air stable yellow to dark brown solids by simple stirring at room temperature. The complexes are isolated as their hexafluorophosphate salts and characterized on the basis of spectroscopic data. The molecular structure of representative complex [(η⁶-C₆Me₆)Ru{(C₅H₄N)₂CN-Me}Cl]PF₆ has been determined by single crystal X-ray diffraction studies.     

Yellow organic light-emitting diodes based on phosphorescent iridium(III) pyrazine complexes: Fine tuning of emission color

The synthesis and luminescence of a series of new iridium pyrazine complexes were investigated. The phosphorescent peak wavelength can be fine-tuned in yellow color range of 553-588 nm. Complexes 4 and 6 were used as representative examples for fabrication of multilayered OLEDs. The two OLEDs all exhibited high efficiency. The devices based on complex 4 exhibited an external quantum efficiency of 4.6% (power efficiency 9.7l m/W) and a maximum brightness of 32 700 cd/m². The device also showed high color purity with an emission maximum at 561 nm and Commission Internationale de l’Eclairage (CIE) coordinates of (x = 0.45, y = 0.54).     

Synthesis of a novel tris-cyclometalated iridium(III) complex containing triarylamine unit and its application in OLEDs

The synthesis of the tris-cyclometalated iridium(III) complex [Ir(DCP)₃] (HDCP = 1-(N,N-diphenyl-amino)-4-(4-chlorophenyl)-phthalazine) from hydrated iridium(III) chloride and the ligand HDCP under mild reaction conditions was described. The photophysical, electrochemical and electrophosphorescent properties of this complex were investigated. Organic light-emitting diodes (OLEDs) using the complex as a dopant and a blend of poly(vinylcarbazole) (PVK) with 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazol (PBD) as a host exhibited bright red emission at 620 nm with the Commission Internationale de l’Eclairage (CIE) coordinate of (0.67, 0.32). A maximum external quantum efficiency of 13.6% photos/electron with a luminous efficiency of 7.4 cd/A at a current density of 0.73 mA/cm², and a maximum luminance of 2941 cd/m² at 99 mA/cm² were obtained in the device at 4 wt% doping concentration.     

Synthesis, structures and luminescent behaviour of tridentate salicylaldiminato-type borate complexes

Treatment of the ligands 3,5-tBu₂-2-(OH)C₆H₂CHNR [R = 2-(CO₂H)C₆H₄ (1a) and 2-(CO₂H)C₁₀H₆ (1b)] with trimethylborate, B(OMe)₃, in toluene yields, after work-up, the yellow crystalline complexes {[3,5-tBu₂-2-(O)C₆H₂CHNR]B(OMe)} [R = 2-(CO₂)C₆H₄ (2a) and 2-(CO₂)C₁₀H₆ (2b)], respectively. Further treatment of these complexes with trifluoromethanesulfonic (triflic) acid, CF₃SO₃H, followed by recrystallisation from tetrahydrofuran (thf) afforded the triflate salts [{3,5-tBu₂-2-(O)C₆H₂CHNR}B(thf)][CF₃SO₃] [R = 2-(CO₂)C₆H₄ (3a) and 2-(CO₂)C₁₀H₆ (3b)]. An electroluminescent device was constructed using 2a, which produced orange-green light with broad emission spectra (maximum brightness of 5 cd/m² being observed at 13 V). Compounds 1a and 2b·2MeCN have been characterised by single crystal X-ray structure determinations.     

Color tunable phosphorescent iridium complexes with substituted 2-phenylthiazoles as the cyclometalated ligands

Several new iridium complexes with substituted 2-phenylthiazoles as the cyclometalated ligands have been synthesized and characterized to try to investigate the effect of the size of the π system and substituent groups on physical properties. The complexes have the general structure of (C^∧N)₂Ir(acac), where the C^∧N are 2-phenylthiazole (ptz), 2-(4-methylphenyl)thiazole (mptz), 2-(4-ethylphenyl)thiazole (eptz). The absorption, emission, cyclic voltammetry and thermostability of the complexes were systematically investigated. The experimental results revealed that the maximum emission wavelength in CH₂Cl₂ at room temperature are in the range 542-547 nm, which is blue shift than that of the known iridium(III) bis(2-phenylbenzothiazolato-N,C^2′) acetyl acetonate (bt)₂Ir(acac) due to decreasing the size of the π system in the benzothiazole portion of 2-phenylbenzothiazole ligand.     

Synthesis, structures and DNA binding of ternary transition metal complexes M(II)L with the 2,2-bipyridylamine (L = p-HB, M = Co, Ni, Cu and Zn)

New ternary transition metal complexes of formulations [Co(bpa)(p-HB)₂](bpa = 2,2′-bipyridylamine, p-HB = p-hydroxybenzenecarboxylic acid) (1), [Ni(bpa)(p-HB)(H₂O)₂]⁺(NO₃)⁻ · H₂O (2), , [Cu(bpa)(p-HB)Cl] (4) and [Zn(bpa)(p-HB)₂]₂ · 0.5H₂O (5) are prepared, their structural features are characterized by crystal structural studies, and their DNA binding propensity has been evaluated by fluorescence method. The molecular structure of complex 1 shows the six coordinate octahedral geometry with one bpa and two p-HB ligands, complex 2 is the cationic complex and has the six coordinate octahedral structure with one bpa, one p-HB and two aqua ligands, complex 3 is also the cationic complex of octahedral coordination with two bpa and one p-HB ligands, complex 4 is five coordinate distorted square pyramidal with one bpa, one p-HB and chloride ligands and complex 5 has the distorted octahedral coordination with two p-HB and one bpa ligands. In all of the complexes, both bpa and p-HB act as the bidentate N and O-donor ligands, respectively. The intermolecular H-bond networks, together with π-π interaction in their solid state are also described. The complexes show the competitive inhibition of ethidium binding to DNA, and the DNA binding propensity can be reflected as the relative order: 3 > 2 > 1 > 5 > 4, in which the cationic charged Ni(II) complexes 2 and 3 show the most effective inhibition ability.     

Solid state and solution NMR, X-ray and antimicrobial studies of 1:1 and 2:1 complexes of silver(I) cyanide with alkanediamine ligands

Several complexes of AgCN with alkanediamine ligands (where the ligands are ethylenediamine, propane-1,3-diamine, butane-1,4-diamine, N,N′-dimethyl-ethylenediamine, N,N′-di-iso-propyl-ethylenediamine, etc.) have been synthesized and structurally characterized. In these species, alkanediamine ligands act as chelating ligands. The X-ray structure of the complex cyano-(N,N′-di-iso-propyl-ethylenediamine)-silver(I) was determined. These complexes have been also characterized by IR, solution as well as solid-state NMR studies. There are two types of IR absorptions observed for mono and dinuclear complexes. For the mono nuclear complexes, a sharp CN band is observed between 2111 and 2131 cm⁻¹ range, whereas for binuclear complexes the bands are in the range 2136-2140 cm⁻¹. The effect of the size of the ligands as well as their substituents is discussed. The antimicrobial activity studies of AgCN and its complexes show that the former exhibits substantial antibacterial activities compared to its complexes.     

Synthesis, reactivity, and structures of dialuminum complexes containing linked ketiminate ligands

Linked bis(ketimine) (1) can be prepared with the reaction of excess 2,4-pentanedione and 4,4′-methylene-bis(2,6-diisopropylaniline) in methanol in the presence of catalytic amount of formic acid. The dialuminum alkyl complexes containing the linked bis(ketiminate) dianionic ligands, [OC(Me)CHC(Me)N(2,6-ⁱPr₂C₆H₂-4)AlR₂]₂CH₂ (2, R = Me; 3, R = Et), were prepared by a reaction of 2 equiv AlR₃ with [OC(Me)CHC(Me)NH(2,6-ⁱPr₂C₆H₂-4)]₂CH₂ in methylene chloride. Reactions of 2 with 2 and 4 equiv of I₂ gave corresponding aluminum iodo complexes 4 and 5, respectively. Treatment of 5 with 2 equiv of AgBF₄, however, gave a diboron complex, [OC(Me)CHC(Me)N(2,6-ⁱPr₂C₆H₂-4)BF₂]₂CH₂ (6), in 18% isolated yield. All new complexes have been characterized by ¹H and ¹³C NMR spectroscopy and complexes 2, 3, and 6 are also confirmed by X-ray diffraction.     

Remarkable chiral and luminescent properties of novel Yb(III) and Eu(III) complexes containing BINAPO ligand

Lanthanide complexes are of great importance for their prospective applications in wide range of science and technology. Chiral lanthanide complexes can constitute stereo-discriminating probes in biological media, owing to the luminescent properties of the rare-earth ions. Sensitized emission with narrow bandwidth, having fast radiation rate and high emission quantum efficiency are the main perspective for synthesizing the complexes. Attention has been given on remarkable chirality with high dissymmetry factors (g = Δε_ext/ε_max) of the complexes. For this purpose, beta-diketonato ligands with chiral BINAPO (1,1′-binapthyl phosphine oxide) ligand were chosen to achieve the goal. The complexes [Ln(TFN)₃(S-BINAPO)](TFN = 4,4,4-trifluoro-1(2-napthyl)-1,3-butanedione), [Ln(HFT)₃(S-BINAPO)] (HFT = 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione) and [Ln(HFA)₃(S-BINAPO)](hfa = hexafluoroacetylacetonate) (where Ln = Yb, Eu) were synthesized. The complex, [Eu(TFN)₃(S-BINAPO)] gives strong red emission at 615 nm with narrow emission band (<10 nm) when excited by 465 nm light with quantum efficiency 86%. The dissymmetry factors (g = Δε_ext/ε_max) corresponding to the ⁷F₁ → ⁵D₀ transition at 590 nm is 0.091 for [Eu(TFN)₃(S-BINAPO)] and for [Yb(hfa)₃(S-BINAPO)](hfa = hexafluoroacetylacetonate) corresponding to the ²F_7/2 → ²F_5/2 transitions is 0.12, are among the largest values for both Eu and Yb complexes to date, respectively. The Eu complexes, [Eu(HFT)₃(S-BINAPO)] and [Eu(TFN)₃(S-BINAPO)] are found to be spontaneously emissive, showing bright red emission, when placed in sunlight or even in the laboratory when light is switched on.     

Design, Syntheses, and Characterization of a Sterically Encumbered Dioxo Molybdenum (VI) Core

Dioxo-Mo^VI complexes of general formula Tp^∗MoO₂(p-SC₆H₄Dn) (6a-6c) (where Tp^∗ = hydrotris(3,5-dimethyl-pyrazol-1-yl)borate and Dn = dendritic unit) have been synthesized and characterized by spectroscopy and mass spectrometry. ¹H NMR spectra of the metal complexes indicate that the C_s local symmetry about the metal core does not change by the incorporation of dendritic functionality at the thiophenolato ring. Electrochemical data show a ∼20 mV change in the redox potential in the complexes with dendritic ligands suggesting a very small perturbation in the redox orbital, which is also supported by small changes in the electronic spectra. The peak-to peak separation (ΔE_p) increases from 125 mV in 6(a) to 240 mV in 6(c), suggesting sluggish electron transfer in molecules with larger dendritic ligands.     

Synthesis, crystal structure, cytotoxic activities and DNA-binding properties of new binuclear copper(II) complexes bridged by N,N′-bis(N-hydroxyethylaminoethyl)oxamide

Two new μ-oxamido-bridged binuclear copper(II) complexes with formulae of [Cu₂(heae)(pic)₂] (1) and [Cu₂(heae)(Me₂phen)₂](ClO₄)₂ · H₂O (2), where heae and pic stand for the anion of N,N′-bis(N-hydroxyethylaminoethyl)oxamide and 2,4,6-trinitrophenol, respectively, and Me₂phen represents 2,9-dimethyl-1,10-phenanthroline; have been synthesized and characterized by elemental analyses, molar conductivity measurements, IR and electronic spectra studies. The crystal structures of the two binuclear copper(II) complexes have been determined by X-ray single-crystal diffraction. In both the two binuclear complexes the central two copper(II) atoms are bridged by trans-heae. In complex 1 the coordination environment around each copper(II) atom can be described as a distorted octahedral geometry, while in complex 2 each copper(II) atom displays a square-pyramid stereochemistry. Hydrogen bonding and π-π stacking interactions link the binuclear copper(II) complex 1 or 2 into a 3D infinite network. The cytotoxicities of the two binuclear copper(II) complexes were tested by Sulforhodamine B (SRB) assays against human hepatocellular carcinoma cell SMMC-7721 and human lung adenocarcinoma cell A549. Both of the two binuclear copper(II) complexes exhibit potent cytotoxic effects against SMMC-7721 and A549 cell lines. The interactions of the two binuclear complexes with herring sperm DNA (HS-DNA) are investigated by using absorption and emission spectra and electrochemical techniques and viscometry. The results suggest that both the two binuclear copper(II) complexes interact with HS-DNA in the mode of intercalation with the intrinsic binding constants of 1.73 × 10⁵ M⁻¹ (1) and 1.92 × 10⁶ M⁻¹ (2). The influence of structural variation of the terminal ligands in the binuclear complexes on DNA-binding properties is preliminarily discussed.     

Synthesis, structure and thermochemical behavior of bis-(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)-(1,4,7,10,13,16-hexaoxa-cyclooctadecane)-strontium in comparison with its structural and thermochemical analogous

The trans-[M(18-crown-6)(C₅HO₂F₆)₂] (M = Ca, Sr, Ba, Pb) complexes have been synthesized and identified. The crystal structure of the Sr complex has been determined by X-ray diffraction. The basic structural unit is the mononuclear complex trans-[Sr(18-crown-6)(C₅HO₂F₆)₂]. The thermal properties of the complexes have been correlated to their structure. The melting and decomposition ranges of the Ca, Sr and Ba complexes and their sublimation temperatures at ∼10⁻² mm Hg have been determined. Experimental evidence is presented that the complexes are similar in volatility.     

Carbazole and arylamine functionalized iridium complexes for efficient electro-phosphorescent light-emitting diodes

We report the synthesis and characterization of four cyclometalated iridium complexes based on carbazole and arylamine modified 2-phenylpyridine. The carbazole and arylamine groups are linked to 2-phenyl pyridine backbone to enhance the energy harvesting and transfer from host to guest materials. The electrochemical and photophysical properties of the complexes are studied and electroluminescent devices are fabricated. The results show that the complexes with ligands containing carbazole moieties have desirable phosphorescent properties. The device with complex 3 doped PVK (poly (vinylcarbazole)) as emission layer achieves maximum luminous efficiency of 6.56 cd A⁻¹ and maximum brightness of 14448 cd m⁻².     

Phloroglucinol-bridged trinuclear complexes with three paramagnetic octahedral nickel(II) ions: Syntheses, crystal structures, and magnetic properties

Three new C₃-symmetric tritopic ligands with a central phloroglucinol bridging unit have been synthesized and characterized. The ligands are accessible through Schiff-base condensation of 2,4,6-triformylphloroglucinol with 2-aminomethylpyridine (H₃tfpg-ampy), N,N-bis(pyridin-2-ylmethyl)-ethylenediamine (H₃tfpg-unspenp), and benzhydrazide (H₆tfpg-bhy). These ligands differ in nature and number of the donor atoms within the resulting binding pockets. Based on these ligands the synthesis of the first trinuclear phloroglucinol-bridged nickel(II) complexes with three octahedrally coordinated nickel centers is reported. The ligands H₃tfpg-ampy and H₆tfpg-bhy, which provide tridentate binding pockets, react with nickel(II) perchlorate in the presence of bis(pyridin-2-ylethyl)-amine (bpea) as an additional tridentate capping ligand leading to the formation of the trinuclear complexes [Ni₃(tfpg-ampy)(bpea)₃](ClO₄)₃ and [Ni₃(tfpg-bhy)(bpea)₃](ClO₄)₃, respectively. Due to the pentadentate binding pocket in ligand H₃tfpg-unspenp, no additional coligand is needed and a water molecule occupies the sixth coordination site at the nickel(II) ion resulting in the complex [Ni₃(tfpg-unspenp)(H₂O)₃](ClO₄)₃. Temperature-dependent magnetic measurements reveal overall weak antiferromagnetic exchange interactions within the trinuclear complex together with a rather strong zero-field splitting (ZFS) for the nickel(II) ions. The observed isotropic coupling constants for the three complexes are in the range of 0.14 < − J < 0.37 cm⁻¹, whereas for the zero-field splitting parameter ∣D∣ values between 1.8 and 5.5 cm⁻¹ are found. This is indicative for competitive spin-polarization and superexchange mechanisms, with the latter prevailing the interaction between the nickel(II) ions through the meta-phenylene-linkage for the complexes reported.     

Synthesis, characterization, and cytotoxicity of trimethylplatinum(IV) complexes with 2-thiocytosine and 1-methyl-2-thiocytosine ligands

The reaction of [PtMe₃(MeOH)(bpy)][BF₄] (1) with the thionucleobases 2-thiocytosine (SCy, 2) and 1-methyl-2-thiocytosine (1-MeSCy, 3) resulted in the formation of the complexes [PtMe₃(bpy)(SCy-κS)][BF₄] (4) and [PtMe₃(bpy)(1-MeSCy-κS)] [BF₄] (5), respectively. The complexes were characterized by ¹H and ¹³C NMR spectroscopy as well as by single-crystal X-ray analyses of 4 · MeOH and 5. In 4 · MeOH two strong hydrogen bonds (N4-H?N3′: N4?N3′ 2.976(7) Å) between the thiocytosine ligands give rise to base pairing thus forming dinuclear cations [{PtMe₃(bpy)(SCy-κS)}₂]²⁺. In both complexes the platinum atom is octahedrally coordinated [PtC₃N₂S] by three methyl ligands, the 2,2′-bipyridine ligand and the κS coordinated nucleobase (configuration index: OC-6-33). The structural investigations gave evidence that the sulfur atoms of the nucleobase ligands in 4 · MeOH and 5 have to be regarded as sp³ and sp² hybridized, respectively. Thus, the ligand in 4 · MeOH has to be considered as the deprotonated thiol-amino form of thiocytosine being reprotonated at N1. In complex 5 the 1-MeSCy is coordinated in its thione-amino form. DFT-calculations of the base-paired dinuclear cation in 4 as well as of 4 itself gave proof of the strength of the hydrogen bond (8.5 kcal/mol) and exhibited that cation-anion interactions influence the conformation of the complex. In vitro cytotoxicity studies of 4 and 5 using nine different human tumor cell lines revealed moderate cytotoxic activity.     

Synthesis and characterization of gold(III) complexes with alkyldiamine ligands

A series of gold(III) metalacycle of five-, six- and seven-membered ring was prepared by reacting Auric acid (HAuCl₄ · 3H₂O) with 1 equiv. unsubstituted ethylenediamine (en), propylene diamine (pn) and butylenediamine (bn) ligands and with some N-mono-substituted as well as N,N′-disubstituted ethylenediamine ligands. The general formula of these complexes is [Au(alkyldiamine)Cl₂]Cl. These complexes are characterized by melting point and elemental analysis, while structural analysis was done by spectroscopic techniques such as UV-Vis, Far-IR, IR spectroscopy, ¹H and ¹³C solution as well as ¹³C and ¹⁵ N solid-state NMR. The solid-state ¹⁵ N NMR shows that the chemical shift difference between free and bound ligand decreases as bn > pn > en, indicating stronger Au-N bond for bn complex compared to pn and en. UV-Vis shows relative stability of the Au(III) complexes of unsubstituted ethylenediamine with respect to N,N′-di-substituted ethylenediamine. Far-IR data show the six-membered metalacycle gold(III) alkanediamine complexes to be more stable. Spectroscopic data are evaluated by comparisons with calculated data of the built and optimized structure by gaussian03 at the RB3LYP level with LanL2DZ bases set.     

Zinc(II) chlorido complexes of protonated kinetin and its derivatives: Synthesis, properties and X-ray structure of [Zn(Hkinetin)Cl3]·kinetin

The syntheses and characterization of five novel zinc(II) complexes with protonated kinetin (6-furfurylaminopurine) and its derivatives are described. Based on the results following from elemental analyses (C, H, N), FTIR, Raman, ¹H and ¹³C NMR spectroscopy, conductivity measurements, thermogravimetric (TG) and differential thermal analyses (DTA), and single crystal X-ray analysis, the complexes of the general composition [Zn(HLⁿ)Cl₃]·xLⁿ (1-5) have been prepared, where L¹ = kinetin (6-furfurylaminopurine), L² = 6-(5-methylfurfurylamino)purine, L³ = 2-chloro-6-furfurylaminopurine, L⁴ = 2-chloro-6-(5-methylfurfurylamino)purine and L⁵ = 2-chloro-6-furfurylamino-9-isopropylpurine, and x = 1/2-2. The structure of [Zn(HL¹)Cl₃]·L¹ (1) has been determined by single crystal X-ray analysis. The Zn(II) atom is tetrahedrally coordinated by three chlorido ligands and one N3-protonated organic molecule forming a ZnCl₃N donor set. The organic ligand L¹ is coordinated to the Zn(II) centre through the N7 atom of the purine moiety. NMR spectroscopic study confirmed the N3 and N7 atom to be the protonation, and coordination site, respectively.     

Syntheses, electrolytic behaviour and antifungal activities of Zn(II) complexes of isomers of 3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane (L). Crystal and molecular structure of [ZnLB(NO3)]NO3 (LB = a,e,a,e-L)

The isomeric cyclam ligands Me₈[14]anes, designated by L_A, L_B and L_C, produce, on reaction with zinc(II)nitrate, zinc(II)sulphate or zinc(II)chloride corresponding complexes, i.e. dinitrato/mononitrato-nitrate complexes [ZnL(NO₃)₂]/[ZnL(NO₃)](NO₃) (L = L_A, L_B or L_C, where the indices A, B and C refer to differing orientations of the four methyl groups on secondary carbons of Me₈[14]ane)_, the diaqua-sulphates [ZnL(H₂O)₂]SO₄ (L = L_A, L_B or L_C), and the diaqua dichloride and dichlorido complexes [ZnL(H₂O)₂]Cl₂ (L = L_A or L_C) or [ZnL_BCl₂], respectively. The complexes have been characterised on the basis of elemental analyses, IR, UV-Vis, ¹H and ¹³C NMR spectroscopies, magnetic and conductance data. The structure of [ZnL_B(NO₃)](NO₃) has been determined by X-ray crystallography. The zinc centre is coordinated to a N₄O donor set in a square-pyramidal geometry. The complexes show differing electrolytic behaviour in different solvents. In chloroform, the complexes are non-electrolytes, indicating that both anions are coordinated to Zn²⁺. Antifungal activity of the ligands and complexes against the phytopathogenic fungi Alternaria alternata and Colletotrichum corcolei have been investigated, and positive results were noted.     

New amino-dithiaphospholanes and phosphoramidodithioites and their rhodium and iridium complexes

New sulfur derivatives of phosphoramidite ligands were synthesized and the impact of the sulfur unit on the spectroscopic properties of their rhodium and iridium complexes was investigated. The new ligands Bn₂NPSCH₂CH₂S^a(P-S^a) (Bn = benzyl, 4), Bn₂NPSCHCHS^a(CH₂)₃C^aH₂(P-S^a)(C^a-S^a) (6) and Bn₂NP(4-XC₆H₄OMe)₂ (X = S, 7a; X = O, 7b) were converted to the rhodium and iridium complexes trans-[Rh(CO)Cl(L)₂] (L = 4, 6, 7), [RhCl(COD)(L)] (L = 4, 6, 7), [IrCl(COD)(7a)] and [IrCl₂Cp∗(6)]. For comparison, some phosphoramidite complexes of these formulations also were synthesized. The new metal complexes were spectroscopically analyzed. For the carbonyl complexes, the ν_CO IR stretching frequencies were lower than for the corresponding phosphite and phosphoramidite ligands. The ¹J_PRh coupling constants for the rhodium complexes with the new ligands were also smaller than for the respective phosphoramidite and phosphite complexes. Finally, the ¹J_PSe coupling constants of the selenides of the new ligands were lower than those of the phosphoramidite ligands but higher than for PPh₃. The spectroscopic data reveal that the new thio ligands 4, 6 and 7a are more electron donating than phosphites and phosphoramidites but less electron donating than PPh₃.