The coordination chemistry of transition metals has become a promising solution to the high demand for the design of drugs for chemotherapy and radiotherapy purposes. The binding mode of various organic molecules around the fac-[Re(CO)3]+ moiety has significantly contributed to the preparation of various coordination compounds with a variety of specific applications. Herein, we report the synthesis and characterization of a non-radioactive rhenium complex fac-[Re(CO)3(H2dpp)Cl] (1) that was isolated from the reaction of Re(CO)5Cl with a heterocyclic tetraamine compound, (8E,10E)-1,4,8,11-tetraazacyclotetradeca-8,10-diene (H2tazd) in toluene. The crystals of compound 1 were crystallographically analysed using single X-ray diffraction techniques. The crystal structure of compound (1) is dominated by the unusual in situ ring rearrangement/reduction of the used H2tazd ligand into the saturated and coordinated dodecahydropyrimido[2’,1′:3,4]pyrazino[1,2-a]pyrimidine (H2dpp) ligand. This complex is a monomeric rhenium complex with H2dpp coordinating neutrally as a bidentate N,N′-donor chelate. The coordinated chelate; H2dpp is also a result of the intramolecular conversion process via the new C–N bond formation leading to a system with three fused rings. The refinement of compound 1 predicts the ring formation in the ligand, and this phenomenon is rare in the coordination chemistry of rhenium and was probably catalysed by rhenium(I) in the complex.

Herein we report the zwitterionic pentagonal bipyramidal oxidorhenium(V) complex trans -[ReOI 2 (bpp)] where bpp is (1E,3E)-1,3-bis(pyrimidin-2-ylimino)propan-2-ide anion. The complex trans -[ReOI 2 (bpp)] was unusually formed from the reaction of trans -[ReOI 2 (OEt)(PPh 3 ) 3 ] with 2-aminopyrimidine in propan-2-ol in the presence of triethylamine (Et 3 N). The anionic ligand bpp was formed by oxidorhenium(V)-catalysed dehydroxylation of propane-2-ol followed by condensation with 2-aminopyrimidine, and coordinates to the [ReO] 3+ core as tetradentate N-donor chelate. A few numbers of pentagonal bipyramidal complexes are known for oxidorhenium(V), and the complex trans -[ReOI 2 (bpp)] is another example. The complex was analyzed by 1 H NMR, IR, UV-visible and single crystal X-ray crystallography. In addition, density functional theory (DFT) was also studied.

A new complex of Zn(II), with 5-chloro-2-methylbenzoxazole ligand (L), has been synthesized by the reaction of zinc dichloride with the ligand (L= C8H6ClNO) in ethanol solution: dichloridobis(5-chloro-2-methyl-1,3-benzoxazole)-zinc(II), C16H12Cl4N2O2Zn. The synthesized complex has been fully characterized by elemental analysis, molar conductivity, FT‑IR, UV‑Vis, and single-crystal X-ray diffraction (XRD).  The XRD analysis reveals that the complex has a 1:2 metal-to-ligand ratio. The zinc(II) complex has a distorted tetrahedral geometry with two coordinated nitrogen atoms from the ligand. Density Functional Theory (DFT) calculations were performed at the B3LYP level of theory using the LANL2DZ basis set for metal complex and the 6-31G(d) basis set for non-metal elements to determine the optimum geometry structure of the complex, and the calculated HOMO and LUMO orbital energies were presented. A natural bond orbital (NBO) analysis was carried out on the molecules to analyze the atomic charge distribution before and after the complexation of the ligand.  The Hirshfeld surface mapped over dnorm, shape index, and curvature exhibited strong H...Cl/Cl...H and H...H intermolecular interactions as the principal contributors to crystal packing.

ABSTRACT. A novel distorted square-planar palladium(II) complex of the type [Pd(Hdz)(PPh3)Cl], where (Hdz = dithizone mono deprotonate and PPh3 = triphenylphosphine), was synthesized in dichloromethane reactions between PdCl2 and a mixture of Hdz and PPh3. The new Pd(II) complex has been identified by FT-IR, electronic spectra, DFT calculations, molar conductivity, and single-crystal X-ray diffraction. An X-ray diffraction study revealed the structure of this complex, indicating distorted square planar coordination geometry around the Pd(II) ion by N, S, P, and Cl donor atoms. XRD analysis has also shown that the Pd(II) complex contains one five-membered ring formed by the coordination of the Hdz ligand through the nitrogen and sulfur atoms to the palladium metal center. To comprehend the strength of nucleophilic and electrophilic attack between the ligands and metal ions, the natural bond orbital (NBO) was used. Finally, density functional theory (DFT) was used to show the molecular reactivity and stability of the ligands and palladium complex. KEY WORDS: Palladium(II), Dithizone mono deprotonated, Distorted square planar geometry, NBO analysis, DFT calculations Bull. Chem. Soc. Ethiop. 2022, 36(3), 617-626. \ DOI: https://dx.doi.org/10.4314/bcse.v36i3.11

以三苯基膦（PPh 3 ）为共配体,合成了 2种新的铜（Ⅰ）和铜（Ⅱ）与菲啶（Phend）的配合物,其组成为[Cu（κ~1-Phend） 2 Cl 2 ] （1）和[Cu 2 (κ 1 -Phend) 2 （κ~1-PPh 3 ） 2 （μ-Cl） 2 ]（2）。这些配合物的结构通过元素分析、摩尔电导率、FT-IR、UV-Vis和单晶X射线衍射进行了研究。典型配合物1的X射线衍射分析显示,Cu（Ⅱ）配位构型为扭曲的平面四方形,而双核配合物2的Cu（Ⅰ）中心为含μ-Cl - 离子的不规则四面体构型。FT-IR谱、元素分析以及UV-Vis谱证实了它们的成分、几何形状和配体相互作用。2种配合物的结构通过密度泛函理论（DFT）计算进行了优化,以解释电子光谱特性。

A novel mononuclear complex of the type [Zn(S-2-BIT)(3)(O-SO3)(CH3OH)(2)] (where 2-BIT = 2-benzimidazolethiole) was synthesized and its structure was investigated by elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and single crystal X-ray diffraction. The crystal structure of the complex show that, crystallizes in the triclinic P (1) over bar space group, with a=9.2946(13) angstrom, b= 10.1997(13) angstrom, c= 17.345(3) angstrom, beta=105.494(7) angstrom, V= 1516.3(4) angstrom(3), R1= 0.0316, wR(2) = 0.0843. In this complex, the distorted tetrahedral arrangement around the Zinc(II) atom is formed by three sulfur atoms from the 2-MBI ligand and one oxygen atom from the sulfate ion, and the crystal lattice structure of the complex also contains two uncoordinated methanol molecules that formed N-H ... O and O-H center dot center dot center dot O intermolecular hydrogen bonds.

Two new complexes of copper(I) and copper(II) with phenanthridine (Phend) of the following composition: [Cu(kappa(1)-Phend)(2)Cl-2] (1) and [Cu-2(kappa(1)-Phend)(2)(kappa(1)-PPh3)(2)(mu-Cl)(2)] (2) have been prepared in the presence of triphenylphosphine (PPh3) as a co-ligand. The structures of these complexes have been investigated by elemental analysis, molar conductivity, FT-IR, UV-Vis, and single-crystal X-ray diffraction. X-ray diffraction analysis of typical complex 1 reveals the distorted square planar geometry around copper(II) whereas the binuclear complex 2 was irregular tetrahedral geometry around Cu (I) center containing bridge Cl- ion. The FT-IR spectra, elemental analysis as well as UV-Vis spectra confirmed their components, geometries, and ligand interactions. The structures of both complexes have been optimized by density-functional theory (DFT) calculations to explain the electronic spectral properties.

The reactivity of the rhenium(I) precursor fac-[Re(CO)(5)Cl] with various benzo-fused ligands were studied. 2-Aminobenzothiazole (abt), mercaptobenzimidazole (mbi), N-(1,3-benzothiazol-2-yl)-2-chloroac-etamide (bct), ethyl-(1H-benzimidazol-2-yl-sulfanyl)acetate (bsa) and (dibenzothiazol-2-yl)tetraazathiapentalene (dbt) were chosen as the ligands of interest, where all ligands coordinated in a monodentate mode. The novel complexes isolated were fully characterized, with abt, mbi and dbt (L) resulting in rhenium complexes of the type fac-[ReCl(L)(2)(CO)(3)]. However, the ligands bct and bsa produced [ReCl(bct)(CO)(3)(NCMe)] and the bridged species (mu-Cl)(2)[Re(bsa)(CO)(3)] respectively. (C) 2021 Elsevier Ltd. All rights reserved.

The reaction of dithizone (H2dtz) with an organometallic rhenium(I) precursor; [Re(CO)5Cl] in ethanol led to the isolation of the octahedral organometallic fac-[Re(CO)3]+ core complex fac-[Re(CO)3(Hdtz)(dttz)] (1). The chelating ligand 1,2-diphenyltetrazolethione-5 zwitterion (dttz) in 1 was formed from the double deprotonation and cyclisation of dithizone in ethanol. The cyclisation of H2dtz to dttz zwitterion is a good example of the conversion of N,S-donor dithizone to S-donor ligand. Both dithizone anion Hdtz− and neutral zwitterion dttz coordinated to the fac-[Re(CO)3]+ core in which Hdtz− is coordinated as bidentate chelate via thiolate sulfur and azoic nitrogen atoms while dttz coordinated as monodentate ligand via thione sulfur atom. In addition to the synthesis, infra-red, 1H NMR, electronic properties and X-ray crystal structure of the complex 1 are reported.

Rhenium(I) and (VII) complexes with cyclohex-1-enylolonium cation and bridging pyridyl derivatives are reported. Additionally, the CO-bridged pyridyl and their related compounds have shown interesting behaviour in their reactivity towards compounds containing two amino groups. The unusual cationic compound: (2,6-diaza-cyclohex-1-enylolonium)2-aza-benzoate (H2den), was isolated from the reaction mixture of 1,2-di(pyridin-2-yl)ethane-1,2-dione with propane-1,3-diamine in methanol. The latter ligand: H2den, was used in the synthesis of rhenium(I) complex in its reaction with [Re(CO)5Cl] that gave rise to novel rhenium(I) complex fac-[Re(CO)3(Hhdm)] (1). The surprising aspect in the formation of (1) is the modification of H2den which was stabilized into a coordinated six-membered pyrimidine ring, 1,4,5,6-tetrahydropyrimidin-2-yl)di(pyridin-2-yl)methanol (H2hdm) chelate. The derived ligand acts as a tridentate monoanionic N2,O-donor ligand towards the fac-[Re(CO)3]+ core. Surprisingly, the 2-aza-benzoate counter-ion that was present in the used ligand is not displayed in the crystal structure of complex 1, and might have been stabilized into 2-aza-benzoic acid (picolinic acid). The reaction of the potential tridentate N2,O-donor ligand 2,2′-dipyridylketone (dpk) with trans-[ReOI2(OEt)(PPh3)2] led to the isolation of [ReO3(dpk·OH)] (2). The ligand H2den and the rhenium complexes were spectroscopically characterized, and the structures of H2den, 1 and 2 were established by X-ray diffraction.

The reaction of 5-phenyl-1,3,4-oxadiazole-2-thiol with mercury(II) acetate in ethanol led to the isolation of the complex [Hg(L)2] (1). Further reaction of 1 with a twofold molar excess of triphenylphosphine led to the isolation of [Hg(L)2(PPh3)2] (2). The complex 2 was characterized by infrared, ultraviolet–visible and nuclear magnetic resonance spectroscopy techniques, as well as by X-ray diffraction analysis.

The coordination mode of aroylhydrazones-based ligands to the fac-[ReCO)3]+, [ReO]3+ and [Re2O3]4+ cores is reported. The reaction of di-2-pyridylketone-2-aminobenzoylhydrazone (Hdpa) with [ReCO5Cl] in ethanol led to the complex [Re(CO)3Cl(Hdpa)] (1). Similar reaction using N′((pyridin-2-yl)methylene)benzohydrazide (Hhpmb) and [ReCO5Br] led to the complex [Re(CO)3Br(Hhpmb)] (2). The reaction of 2-hydroxy-N′-((thiophen-3-yl)methylene)benzohydrazide (H2htmb) with trans-[ReOCl3(PPh3)2] in acetonitrile gave the complex cis-[ReOCl2(Hhtmb)(PPh3)] (3). The complexes cis-[ReOBr2(Hhpb)(PPh3)] (4) and (μ-O)[ReO(pbz)2]2 (5) were isolated from the reaction of [ReOBr3(PPh3)2] with salicylhydrazide (Hshz) and trans-[ReO2(py)4]Cl with benzohydrazide (Hbhz) in acetone respectively. The chelating ligands 2-hydroxy-N′-(propan-2-ylidene)benzohydrazide (H2hpb) and N′-(propan-2-ylidene)benzohydrazide (Hpbz) were formed from the condensation of acetone with Hshz and Hbhz respectively upon the reaction of [ReOBr3(PPh3)2] with Hshz in acetone and [ReO2(py)4]Cl with Hbhz in acetone respectively. In addition to the X-ray crystal structures, conductivity, infra-red, 1H NMR and electronic properties are reported.

Rhenium(I) complexes with benzimidazolidines, imidazolidines and their derivatives are reported. This study highlights the unusual synthetic route that led to a series of the unexpected ring-containing benzimidazolidines and imidazolidines, obtained from the reaction of ketone and diamino-containing compounds. The reaction of the bridging pyridyl; 2,2′-dipyridylketone (dpk) with 1,2-diaminobenzene and 1,2-diaminoethane in methanol led to the isolation of 2,3-dihydro-2,2-di(pyridin-2-yl)-1H-benzo[d]imidazole (H2dpb) and 2-(2-(pyridine-2-yl)imidazolidin-2-yl)pyridine (H2pip) respectively. The compounds fac-[Re(CO)3(H2dmb)Cl] (1) and fac-[Re(CO)3(H2pip)]Cl.H2O (2) were isolated in good yield by reacting [Re(CO)5Cl] with 2,3-dihydro-2,2-di(pyridin-2-yl)-1H-benzo[d]imidazole (H2dpb) and 2-(2-(pyridine-2-yl)imidazolidin-2-yl)pyridine (H2pip) in toluene respectively. A surprising aspect of fac-[Re(CO)3(H2dmb)Cl] (1) is the benzimidazolidine ring opening in H2dpb, which resulted in the formation of the neutrally coordinated Schiff-base ligand, N1-(di(pyridine-2-yl)methylene)benzene-1,2-diamine (H2dmb), which acts as a bidentate N,N-donor chelate. On other hand, the H2pip ligand did not undergo any modification. Therefore, it acted as a tridentate N3,O-donor ligand towards the cationic cluster compound with a fac-[Re(CO)3]+ core. The crystal structure of H2dpb, 1 and 2 were determined by X-ray single crystal diffraction, in addition to IR, 1H NMR and electronic analysis.

Platinum(II) complex consisting of the tertiarydiphosphine (dppm) ligand had been prepared from PdCl2 with one equiv. of dppm ligand to form [PtC2(dppmCl)] complex where as dppmCl is bis(dipheny1phosphino) chloromethene. Crystal was grown in dichloromethane by slow evaporation process and characterized by X-ray crystallography technic. The complex structure synthesized based upon the identification using X-ray Crystallography and FTIR was [PtC12(dppmCl)], the ligand dppm coordinated to the meta centre as bidentate chelating ligand and form square planar arrangement around Pt(II) metal centre. The bond distances of Pt-P1, Pt-P2, Pt- Cl1 and Pt-Cl2 are 2.217 (2), 2.217 (2), 2.3661 (19) and 2.3661 Aο respectively. The characterized results of Pt(II) complex using X-ray analysis illustrated that [PtC12(dppmCl)] Complex form monoclinic crystal with unit cell dimensions of a = 16.2034(5), b = 7.8274(2), and c = 19.2496 (6) Aο, with β = 98.918 (1)ο, Z=4, calculated density= 1.838 mg/m3, T= 200 k and space group C2/c

The reaction of the pyrazole-benzothiazole hybrids 2-(3,5-dimethylpyrazol-1-yl)benzothiazole (dmp) and 2-(2-benzothiazolyl)-4,5,6,7-tetrahydro-2H-indazol-3-ol (Hbth) with [Re(CO)(5)Cl] resulted in the formation of neutral complexes with the general formula [ReCl(CO)(3)(HL)] (HL = dmp (1), Hbth (2)). 1-(Benzo [d]thiazol-2-yl)-4-methyl-IH-pyrrol-2-ol (Hbtm) gave the trimeric species [Re(btm)(CO)(3)](3) (3) by reaction with [Re(CO)(5)Cl]. Reaction with [(ReOCl3)-O-v(PPh3)(2)] led to the isolation of the oxo-bridged dimeric compound (mu-O)[ReOCl2(dmp)](2) (4) and [ReOCI(bth)(bth(1))] (5) [bth(1) = 2-(benzo[d]thiazol-2-yl)-1,2,4,5,6,7-hexahydro-3H-indazol-3-one] by reaction with dmp and Hbth, respectively. The reactivity of Hbtm with trans-[ReOCl3(PPh3)(2)] in ethanol gave [ReOCl(btm)(btm(1))] (6) [btm(1) = 2-(benzo[d]thiazol-2-yl)-5-methyl-1,2-dihydro-3H-pyrazol-3-one], whereas [ReOCl(btm(1))(btz)] (7) [btz = 1-(benzo[d]thiazol-2-yl)-4-(1-iminoethyl)-3-methyl-1H-pyrazol-5ol] formed in acetonitrile using the same reactants. The rhenium(V) complexes [ReO(Ome)(btm)(btm(1))] (8) and [ReO(OEt)(0.96)(I)(0.04)(btm)(btm(1))] (9) were isolated upon reacting Hbtm with cis-[ReO2I(PPh3)(2)] in methanol and ethanol, respectively. The structures of complexes 1-9 were determined by X-ray diffraction methods and confirmed spectroscopically. (C) 2019 Elsevier Ltd. All rights reserved.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A complex of (BenzMeIm)(2)[PtCl4] was prepared by the reaction of 1-benzyl-3-methylimidazolium chloride (BenzMeIm-Cl) with PtCl2. The structure of the complex was characterized by single crystal X-ray analysis, and it crystallizes in the monoclinic P2(1)/c space group, with a=0.981 80(5) nm, b=0.861 47(3) nm, c=0.144 332(7) nm, beta=92.480(2)degrees, V=121.96(1) nm(3), R-1=0.014 4, wR(2)=0.038 8. CCDC: 1532135.

The reaction of the potentially bidentate ambidentate N,O-donor ligands 3-hydroxy-2-pyridinecarboxylic acid (Hhpc) and 3-hydroxy-2-(hydroxymethyl)pyridine (Hhhp) with trans-[ReOCl3(PPh3)2] led to the isolation of the products [ReOCl(hpc)2] (1) (from acetonitrile) and [ReOCl2(hhp)(PPh3)] (2) (from ethanol) respectively. In both complexes hpc and hhp are coordinated as bidentate N,O-donor chelates, rather than as O,O-donor ligands. From the reaction of [Re(CO)5Cl] and Hhhp·HCl in ethanol the neutral complex fac-[Re(CO)3Cl(Hhhp)] (3) was obtained, with N,O-coordination of Hhhp. Complex 1 crystallizes in the monoclinic space group P21/n with a = 6.8782(3), b = 20.0647(8), c = 10.8692(4) Å, β = 107.545(1)°, and Z = 4. Complex 2 crystallizes in the triclinic space group P-1 with a = 7.3523(4), b = 8.1047(5), c = 19.591(1) Å, α = 91.133(2)°, β = 93.656(2)°, γ = 93.074(2)° and Z = 2. Complex 3 has monoclinic P21/c symmetry with the cell parameters a = 10.6452(5), b = 11.1372(5), c = 9.7229(5) Å, β = 106.107(2)°, and Z = 4.