Its Cadmium Research Articles

Synthesis, crystal structures and antiproliferative activities of a new indole-containing dipyridylmethanone hydrazone Schiff base and its cadmium(II) complex.

In this study, we introduce a novel indole-containing pyridine-based Schiff base, (E)-2-({[bis(pyridin-2-yl)methylidene]hydrazin-1-ylidene}methyl)-1H-indole, C20H15N5 (2-DPHI), and its cadmium(II) complex poly[[2-({[bis(pyridin-2-yl)methylidene]hydrazin-1-ylidene}methyl)-1H-indole]di-μ-chlorido-cadmium(II)], [CdCl2(C20H15N5)]n (pCd2), as potential anticancer agents. The Schiff base was synthesized by reacting dipyridylmethanone hydrazone with indole-2-formaldehyde, while the cadmium complex was prepared by combining CdCl2 and 2-DPHI in methanol at room temperature. Both compounds were evaluated for their cytotoxicity against three human cancer cell lines (A375, A549 and HeLa) and a normal cell line (HFF-1). The ligand 2-DPHI exhibited notable antitumour activity, with an IC50 value of 12.22 µM against A375 and 15.17 µM against A549 after 48 h, while the pCd2 complex showed an even stronger inhibition of A375 cells, with an IC50 value of 4.88 µM, outperforming both 2-DPHI and CdCl2. Both compounds demonstrated lower toxicity towards normal cells compared to cancer cells. The structures of 2-DPHI and pCd2 were fully characterized using single-crystal X-ray diffraction, elemental analysis, high-resolution mass spectrometry and FT-IR, 1H NMR, 13C NMR and UV-Vis spectroscopy.

New penta-Coordinated Cadmium(II) Complexes: Synthesis, Characterization, Thermal, Antimicrobial, Antioxidant and Cytotoxicity Properties.

In this paper, a new tridentate Schiff base ligand (L) with nitrogen donor atoms and its cadmium(II) complexes with the general formula of CdLX2 (X=Cl-, Br-, I-, SCN-, N3 -, NO3 -) have been synthesized and characterized by physical and spectral (FT/IR, UV-Vis, Mass, and 1H, 13C NMR spectroscopies) methods. Also nano-structured cadmium chloride and bromide complexes were synthesized by sonochemical method and then used to prepare nanostructured cadmium oxide confirmed by XRD and SEM techniques. Thermal behavior of the compounds was studied in the temperature range of 25 to 900 °C under N2 atmosphere at a heating rate of 20 °C/ min. Moreover, thermo-kinetic activation parameters of thermal decomposition steps were calculated according to the Coats-Redfern relationship. Antimicrobial activities of the synthesized compounds against two gram-positive and two gram-negative bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and two fungi of Candida albicans and Aspergillus niger were investigated by well diffusion method. SEM technique was used to monitor the morphological changes of the bacteria treated with the compounds. The 2,2-Diphenyl-1-picrylhydrazyl(DPPH) and the ferric reducing antioxidant power (FRAP) methods were used to evaluate the antioxidant ability of the ligand and its cadmium(II) complexes. In final, the cytotoxicity properties of the ligand and some cadmium(II) complexes against PC3 cancer cells were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) bioassay and nitric oxide (NO) level measurement. The morphological changes of prostate cancer (PC3) cells due to treatment with the ligand and its complexes confirmed their anticancer effectiveness.

New tetradentate long chain Schiff base and its cadmium(II) complexes: Antimicrobial, antioxidant and anticancer activities

In the current study, a new long chain tetra-nitrogen donor Schiff base ligand (SB) entitled as N1,N2-bis(2-(((1E,2E)-3-(4-(dimethylamino)phenyl)allylidene)amino)ethyl)ethane-1,2-diamine and some its molecular cadmium (II) complexes formulated as Cd(SB)X2 (X = halide/pseudohalide) were prepared and characterized by various physicochemical and spectral methods such as melting point, micro-analytical data, thermal analysis (TG/DTG/DTA), molar conductivity and UV–Visible, FT-IR, 1H, and 13C NMR spectroscopies. Also nanostructured cadmium chloride and iodide chelate complexes approved by PXRD SEM and EDX techniques were synthesized to use as precursor to prepare nanostructure cadmium oxide. The particle sizes about 2–10 nm were estimated for nanostructured cadmium complexes and oxide. Thermo-gravimetric plots showed the compounds are decomposed via 2–4 steps with weight loss of 69–100% to leave out metallic Cd or cadmium salt as final residue. Thermo-kinetic activation parameters calculated based on TG plots suggested non-spontaneous thermal decomposition with activation Ea*, ΔH* and ΔG* parameters in the ranges of (13.54–160.48 kJ.mol−1), (8.22–155.95 kJ.mol−1) and (1.59 × 102-4.1 × 102 kJ.mol−1) respectively. Moreover, the pharmacological activities of the compounds were investigated against some pathogenic fungi and bacteria. According to screening data, the SB ligand showed lower antimicrobial activities than its complexes toward selected microbes so that the cadmium(II) nitrate, thiocyanate and azide were found the most active against B. subtilis, S. aureus, P. aeruginosa and E. coli respectively. The evaluation of DNA cleavage potency using the agarose gel electrophoresis technique suggested Cd(SB)Cl2 as the most destructive compound. Furthermore, the antioxidant assessment of the compounds as compared with the standard references by DPPH and FRAP methods proposed Cd(SB)Cl2 and Cd(SB)Br2 as the best antioxidant. In final, the cytotoxicity of the synthesized compounds was appraised toward human breast cancer (MCF-7) and prostate cancer (PC3) cell lines employing MTT and nitric oxide level assays. The results suggested Cd(SB)Br2 as more cytotoxic than other complexes against two studied cancer cell lines.

Efficient emission of Zn(II) and Cd(II) complexes with nopinane-annelated 4,5-diazafluorene and 4,5-diazafluoren-9-one ligands: how slight structural modification alters fluorescence mechanism.

Zinc(II) and cadmium(II) chlorido complexes with an N,N-chelating nopinane-annelated 4,5-diazafluoren-9-one ligand (LO) were synthesized. While the zinc(II) complex is mononuclear and adopts a tetrahedral ZnN2Cl2 coordination geometry, its cadmium(II) analogue features a 1D polymeric structure due to the bridging coordination of chlorido ligands with Cd2+ ions having an octahedral CdN2Cl4 coordination geometry. The photophysical properties of the oxygen-containing LO ligand and its zinc(II) and cadmium(II) complexes were studied in solution and in the solid state and matched against the properties of its oxygen-free 4,5-diazafluorene congener L and its complexes of the same metal ions. Comprehensive experimental and theoretical studies revealed the impact of the oxygen atom in the ligand core on the luminescence of the ligands and the complexes. For the oxygen-free L ligand and L-based complexes, the structural differences between the S0 and S1 geometries are small, which leads to fluorescence with extraordinarily small Stokes shifts. The emission of these compounds is of locally excited character for L and of mixed locally excited + ligand-to-halide charge transfer character for the L-based complexes. The introduction of the oxygen atom in the ligand core results in a drastic red-shift of the emission band due to short-range charge transfer. The differences between the S0 and S1 geometries are much more pronounced for LO and LO-based compounds than those of their oxygen-free analogues, leading to an order of magnitude larger Stokes shifts. On going from solution to the solid state, LO and its complexes exhibit aggregation-induced emission (AIE) behaviour with photoluminescence quantum yields (PLQYs) reaching tens of percent.

Cadmium sulphide nanoparticles from Cadmium (II) complex of (Cyclododecylidineamino)thiourea

Novel ligand (Cyclododecylidineamino)thiourea (CDDATU) and its Cadmium (II) complex were synthesized and characterized by IR, CHNS and Thermo gravimetric analysis.The complex was found to give highly crystalline, good quality, mono-dispersed Cadmium sulphide nanoparticles through polyol synthesis method using Glycerol as high boiling solvent. Characterization of Cadmium sulphide nanoparticles were done using SEM, EDX, TEM, UV, PL and PXRD studies.

Thermal and kinetic analysis of a new hydrazone-oxime ligand and its cadmium(II) complex: Synthesis, spectral characterization, crystallographic determination and Hirshfeld surface analysis

A novel cadmium complex, [Cd(L)2](NO3)2(H2O)2, (hereinafter simply designated as CdIIL2) has been synthesized by reacting a hydrazone-oxime ligand, (2E,3E)-3-(2-(6-chloropyridin-2-yl)hydrazono)butan-2-one oxime (L), with cadmium nitrate tetrahydrate. The ligand L and CdIIL2 were characterized by LC/MS-MS, FT-IR, elemental analysis, NMR, molar conductivity, UV–Vis spectroscopy and thermal analysis. The structure of the CdIIL2 was also elucidated by the single-crystal X-ray diffraction technique. The X-ray powder diffraction pattern of CdIIL2 was then performed to confirm the purity of the crystalline compound. Additionally, as a result of analytical and spectroscopic data suggested that the metal in CdIIL2 exhibits a distorted octahedral geometry. Hirshfeld surface analysis (HSA) was used in conjunction with 2D fingerprint plots to evaluate intermolecular forces, involving hydrogen bonds, in the crystal lattice of CdIIL2. Thermal and kinetic studies of the synthesized compounds were performed between 30 and 1000 °C using different heating rates of 5, 10, and 15 °C/min under two different atmosphere (N2 and O2). The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) integral methods have been selected to determine the values of the reaction activation energies (Ea). According to the Ea values, FWO was selected to investigate the thermodynamic parameters, i.e., the free energy change (ΔG), entropy (ΔS) and enthalpy (ΔH) changes. The ligand and its complex exhibited better thermal stability and higher thermodynamic values in O2 atmosphere than in N2 atmosphere.

A new N2O2-donor compartmental Schiff base ligand and its cadmium(II) complex: synthesis, mesogenic and photoluminescent properties

ABSTARCT A new mesomorphic compartmental [N2O2] donor Schiff base ligand [H2L] has been synthesized and one corresponding polymeric cadmium(II) complex of the type [Cd-L]n {H2L = 4,6-bis((E)-1-(octadecylimino)ethyl) benzene-1,3-diol} is prepared by direct reaction of metal ion with ligand. Both the ligand and its Cd-complex do exhibit mesomorphic properties. The IR spectrum of the ligand clearly reveals that the ligand acts as a bi-negative tetradentate donor through the two sets of phenolate oxygen and azomethine nitrogen. Mesomorphic behavior of these compounds are investigated with the help of polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The organization of the ligand and complex molecules in the mesophase are investigated by X-ray diffraction techniques. The Schiff base ligand and its Cd-complex shows plastic columnar mesophase (Colp) at ∼82 and ∼86 °C, respectively. The polymeric Cd-complex is blue light emitter with a broad emission maximum at ∼475 nm on excitation at 380 nm.

Synthesis, characterization, and biological activity of cadmium (II) and antimony (III) complexes based on 2-acetylpyrazine thiosemicarbazones

Two cadmium (II) complexes formulated as [Cd(L1)(HL1)]ClO4 (Cd1) and [Cd(L2)2] (Cd2), also two antimony (III) complexes formulated as [Sb(L1)2]2Cl2·CH3OH (Sb1) and [Sb(L2)Cl2] (Sb2) (HL1 = 2-acetylpyrazine N4-methylthiosemicarbazone, HL2 = 2-acetylpyrazine N4-dimethylthiosemicarbazone) have been synthesized, and the molecular structure of the four complexes have been determined by single crystal X-ray diffraction. The antimicrobial study has been conducted against E. coli and S. aureus, and the results indicated that the antibacterial activity of Cd1 and Sb1 increased to some extent than their ligand HL1, while Cd2 and Sb2 presented fairly effective antibacterial activity mainly the same as their ligand HL2. The four compounds all exhibited improved cytotoxic activity against the human hepatocellular carcinoma HepG2 cells than the ligands. While Cd2 displayed the most effective antiproliferative activity, and also the preferable selectivity for HepG2 cells versus normal QSG7701 cells. It is noted that there was a strong relationship between the activity of the ligand HL2 and its cadmium (Ⅱ) or antimony (III) complexes.

Amino modification of rice straw-derived biochar for enhancing its cadmium (II) ions adsorption from water.

To enhance the adsorption capacity of Cd2+, -NH2 groups were introduced into the rice straw-derived biochar surface by combining nitrification and amination. The batch and continuous Cd2+ adsorption experiments were performed to determine the role of -NH2 groups on the surface of biochar. The physical and chemical characteristics were analyzed for comparison. The results indicated that the adsorption capacity of the modified biochar (BC-NH2) was boosted by 72.1%. The results of continuous adsorption experiments in fixed bed columns showed that the penetration time of BC-NH2 was three times that of original biochar. The adsorption of Cd2+ by BC-NH2 is a spontaneous endothermic chemical reaction, which was obtained by combing sorption kinetics, isotherms and thermodynamic analysis. The Cd2+ adsorption was mainly the complexation between -NH2 group on biochar surface and Cd2+ in solution. Finally, a possible interaction mechanism between Cd2+ and BC-NH2 was proposed.

Cytotoxicity and Molecular Docking Studies of a Novel Enaminone and its Cadmium (II) Complex

Cytotoxicity and Molecular Docking Studies of a Novel Enaminone and its Cadmium (II) Complex

Synthesis, structural and spectroscopic studies of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone N(4)-methyl-N(4)-phenyl thiosemicarbazone and its cadmium(II) complex

Synthesis, spectral and single crystal XRD studies of a novel ligand 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone N(4)-methyl-N(4)-phenylthiosemicarbazone and its cadmium(II) complex have been communicated in this work. The ligand crystallizes in triclinic system with space group P-1, a(Å)=7.8930(4), b(Å)=11.2019(5), c(Å)=13.0211(7); α(°)=96.175(3), β(°)=100.922(3)°, γ(°)=91.005(3)°, V(Å3)=1123.02(10), r(mg/m3)=1.306 and Z=2. Cadmium(II) complex crystallizes in the monoclinic crystal system with space group P21/c, unit cell dimensions a(Å)=9.6939(5), b(Å)=22.5183(11), c(Å)=21.2054(10); α(°)=90, β(°)=99.960(2), γ (°)=90, V(Å3)=4559.2(4) and Z=4. The packing of the molecules in the crystal lattice is stabilized by intermolecular hydrogen bonds. Spectroscopic data along with crystal structure, confirmed the involvement of azomethine nitrogen, thione sulphur and enolic oxygen of pyrazolone moiety in coordination with the metal ion.

Copper(II), cobalt(II), cobalt(III), and tin(IV) 5,10,15,20-tetraphenyl tetrabenzoporphyrinates: Synthesis and properties

The complexation reactions of 5,10,15,20-tetraphenyl tetrabenzoporphyrin and the metal exchange reactions of its cadmium(II) complex with copper(II), cobalt(II), and tin(II) acetates and chlorides in a chloroform–methanol mixture and dimethylformamide were studied spectrophotometrically. Corresponding copper(II), cobalt(II), cobalt(II), and tin(IV) porphyrinates were synthesized and identified.

Cooperative loading and release behavior of a metal-organic receptor.

In order to design artificial chemical systems that are capable of achieving complex functions, it is useful to design synthetic receptors that mimic their biological counterparts. Biological functions are underpinned by properties that include specific binding with high affinity and selectivity, cooperativity, and release triggered by external stimuli. Here we show that a metal-organic receptor constructed through subcomponent self-assembly can selectively and cooperatively load and release oxocarbon anions. The flexible coordination spheres of its cadmium(II) centers allow the receptor to dynamically adjust its structure upon exchanging four triflate or triflimide counterions for two oxocarbon anions, resulting in strong cooperativity and very tight binding, with an apparent association constant for C5O5(2-) of 5 × 10(10) M(-1). Substituting the cadmium(II) ions for copper(I) by switching solvent prompted a structural reorganization and release of the oxocarbon anions. Its cooperative behavior allows the receptor to carry a greater payload than would be possible in a noncooperative analogue.

Synthesis, Crystal Structure, and DNA-Binding Properties of a Cadmium(II) Complex With the Bis(2-benzimidazolymethyl)amine Ligand

A V-shaped ligand Bis(2-benzimidazolymethyl)amine (bba) and its cadmium(II) picrate (pic) complex, with composition [Cd(bba)2](pic)2·4DMF, have been synthesized and characterized on the basis of elemental analyses, molar conductivities, IR spectra and UV-vis measurements. In the complex, the Cd(II) ion is six-coordinated with a N6 ligand set, resulting in a distorted octahedron coordination geometry. In addition, the DNA-binding properties of the Cd(II) complex have been investigated by electronic absorption, fluorescence and viscosity measurements. The experimental results suggest that the Cd(II) complex binds to DNA by partial intercalation binding mode.

Paramagnetic particles coupled with an automated flow injection analysis as a tool for influenza viral protein detection

Currently, the influenza virus infects millions of individuals every year. Since the influenza virus represents one of the greatest threats, it is necessary to develop a diagnostic technique that can quickly, inexpensively, and accurately detect the virus to effectively treat and control seasonal and pandemic strains. This study presents an alternative to current detection methods. The flow-injection analysis-based biosensor, which can rapidly and economically analyze a wide panel of influenza virus strains by using paramagnetic particles modified with glycan, can selectively bind to specific viral A/H5N1/Vietnam/1203/2004 protein-labeled quantum dots. Optimized detection of cadmium sulfide quantum dots (CdS QDs)-protein complexes connected to paramagnetic microbeads was performed using differential pulse voltammetry on the surface of a hanging mercury drop electrode (HMDE) and/or glassy carbon electrode (GCE). Detection limit (3 S/N) estimations based on cadmium(II) ions quantification were 0.1 μg/mL or 10 μg/mL viral protein at HMDE or GCE, respectively. Viral protein detection was directly determined using differential pulse voltammetry Brdicka reaction. The limit detection (3 S/N) of viral protein was estimated as 0.1 μg/mL. Streptavidin-modified paramagnetic particles were mixed with biotinylated selective glycan to modify their surfaces. Under optimized conditions (250 μg/mL of glycan, 30-min long interaction with viral protein, 25°C and 400 rpm), the viral protein labeled with quantum dots was selectively isolated and its cadmium(II) content was determined. Cadmium was present in detectable amounts of 10 ng per mg of protein. Using this method, submicrogram concentrations of viral proteins can be identified.

Synthesis, Crystal Structure, and DNA-Binding Properties of a Cadmium(II) Complex With 1,3-Bis(1-propylbenzimidazol-2-yl)-2-oxapropane

A V-shaped, ligand 1,3-bis(1-propylbenzimidazol-2-yl)-2-oxopropane (pobb), and its cadmium(II) complex, with composition [Cd(pobb)2]·(pic)2·DMF, (pic = picrate), have been synthesized and characterized. The crystal structure of the cadmium(II) complex revealed that the coordination sphere around cadmium(II) is distorted octahedral geometry. In addition, the DNA-binding properties of the ligand pobb and its Cd(II) complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The experimental results suggested that the ligand and its Cd(II) complex bind to DNA via an intercalation binding mode, and their binding affinity to DNA follows the order Cd(II) complex > ligand pobb.

Coordination geometries and crystal structures of cadmium(II) complexes with a new amino alcohol (NN′O) ligand

The new ligand 2-(2-(2-hydroxyethylamino)ethylamino)cyclohexanol, (HEAC), was prepared under microwave conditions through ring opening of cyclohexene oxide with 2-(2-amino-ethylamino)ethanol. Its cadmium(II) complexes [Cd2(HEAC)2(μ-Cl)2Cl2] (1) and [Cd(HEAC)2][CdI4] (2) were identified by elemental analysis, FT-IR, Raman, 1H NMR spectroscopies, and single-crystal X-ray diffraction. HEAC formed 1 : 1 M : L complexes with cadmium chloride and cadmium iodide. Complex 1 crystallized as a dimer with two asymmetrically bound bridging Cl− and a terminally coordinated Cl− on each metal. The geometry around the cadmiums in 1 with four five-membered chelate rings and four Cl− ligands is distorted octahedral for each Cd(II). The cyclohexanol OH of each ligand forms intramolecular hydrogen bonds. In 2, the coordination numbers for cadmium in [Cd(HEAC)2]2+ and [CdI4]2− moieties are six and four, respectively. In [Cd(HEAC)2]2+ each ligand coordinates through two N- and one O-donors, leading to a distorted octahedral geometry. The geometry of [CdI4]2− in 2 is slightly distorted tetrahedral. The protonation equilibrium constants of the two secondary amino groups in HEAC, determined by pH-potentiometry, were 6.26 and 9.26, respectively, at 25°C. Stability constants for this ligand with Ni(II), Cu(II), and Zn(II) (1 : 1 M : L), determined by glass-electrode potentiometry, were 7.13, 10.50, and 5.42, respectively.

Synthesis, structure, and antimicrobial activity of a cadmium(II) complex derived from N,N′-bis(5-chlorosalicylidene)propane-1,3-diamine

The Schiff base, N,N′-bis(5-chlorosalicylidene)propane-1,3-diamine (H2L) derived from 5-chlorosalicylaldehyde and propane-1,3-diamine, and its cadmium(II) complex, bis(μ2-acetato)bis(μ2-N,N′-bis(5-chlorosalicylidene)-1,3-propanediamine)tricadmium(II) Cd[Cd(CH3COO)L]2 (I), have been prepared and characterized by elemental analyses, IR, and single-crystal X-ray diffraction analysis. The crystal of H2L is monoclinic: space group P21/n, a = 11.252(4), b = 8.972(3), c = 16.981(6) A, β = 96.005(4)°, V = 1705.0(10) A3, Z = 4. The crystal of complex I is monoclinic: space group P21/c, a = 11.056(1), b = 22.284(2), c = 8.398(1) A, β = 91.779(1)°, V = 2068.0(3) A3, Z = 2. Complex I is a centrosymmetric trinuclear cadmium(II) complex. The deprotonated Schiff base ligand coordinates to the Cd atoms through the phenolate O and imine N atoms. The effect of the Schiff base ligand and the complex on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.

Preparation and characterization of pentagonal-bipyramidal zinc(II) and cadmium(II) complexes of a neutral N 3S 2 thiosemicarbazone derived from 2N-methylthiosemicarbazide and the X-ray crystal and molecular structures of the free ligand and its cadmium(II) complex, Cd(dap- 2NMetsc)(NO 3) 2

A new pentadentate thiosemicarbazone has been synthesized and structurally characterized by spectroscopic and X-ray diffraction techniques. It reacts with zinc(II) and cadmium(II) nitrate producing crystalline complexes of general formula, [M(dap- 2NMetsc)(NO 3) 2] (M = Zn 2+, Cd 2+; dap- 2NMetsc = 2,6-diacetylpyridine bis( 2N-methylthiosemicarbazone)) which have been characterized by a variety of physico-chemical techniques. X-ray crystallographic structure determination of the free ligand shows that, in the solid state, it remains in the E form about the azomethine bonds with both the thione sulfur and pyridine nitrogen atoms trans to the azomethine nitrogen atoms. A single crystal X-ray structure determination of the [Cd(dap- 2NMetsc)(NO 3) 2] complex shows that the ligand is coordinated to the cadmium(II) ion via the two azomethine nitrogen atoms, the pyridine nitrogen atom and the two thione sulfur atoms. The thiosemicarbazone occupies the equatorial plane and the two nitrate ligands are coordinated to the cadmium atom as monodentate ligands occupying axial positions, the overall geometry of the complex being a distorted pentagonal-bipyramid.

Synthesis and Structural Characterisation of Palladium and Group‐12 Metal Complexes with a Hybrid Phosphanylphosphonate Ferrocene Ligand

AbstractDiethyl [1′‐(diphenylphosphanyl)ferrocenyl]phosphonate (1) was synthesised by stepwise metallation/functionalisation of 1,1′‐dibromoferrocene and studied as a ligand for palladium(II) and group‐12 metals. Treatment of [PdCl2(cod)] (cod = η2:η2‐cycloocta‐1,5‐diene) with 1 in 1:1 or 1:2 molar ratios gave, respectively, the dinuclear, chloride‐bridged complex [{Pd(μ‐Cl)Cl(1‐κP2)}2] (2) and the mononuclear complex trans‐[PdCl2(1‐κP2)2] (3), where 1 coordinates exclusively through the phosphane function. The reactions between 1 and group‐12 metal bromides MBr2 in a 1:1 molar ratio gave the adducts [MBr2(1)] [M = Zn (4), Cd (5), and Hg (6)], whose crystal structures change considerably with the metal ion. Thus, whereas 4 is a molecular complex with 1 coordinating as an O1,P2‐chelate, its cadmium(II) analogue is a polymer built up from symmetric {CdBr(μ‐Br)}2 units interconnected by pairs of O1,P2‐bridging phosphanylphosphonate ligands. Finally, the mercury(II) complex 6 is a halide‐bridged dimer, [{Hg(μ‐Br)Br(1‐κP2)}2]. However, this compound is structurally fluxional in solution (NMR spectra) and, in the crystal, it attains a structure similar to 5 owing to weak interactions between mercury and phosphonate‐O1 atoms from adjacent molecules. An isomer to 6, [{HgBr2(1‐κ2O1,P2)}2] (7), was isolated from attempted alkylation of 6 and structurally characterised as a dimer, where ligands 1 bridge two {HgBr2} units. All compounds were studied by spectroscopic methods (IR, NMR, mass) and the solid‐state structures of 1, 2·${1 \over 2}$ H2O, 3·4 CHCl3, 4, 5, 6·5 C6H6, and 7 have been determined by single‐crystal X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)