Acetic Acid Ligand Research Articles

Crystal structure of catena-poly[[methanoldioxidouranium(VI)]-μ-2-[5-(2-oxidophen-yl)-1H-1,2,4-triazol-3-yl]acetato-κ2 O:O'

In the title complex, [U(C10H7N3O3)O2(CH3OH)] n , the UVI cation has a typical penta-gonal-bipyramidal environment with the equatorial plane defined by one N and two O atoms of one doubly deprotonated 2-[5-(2-hy-droxy-phen-yl)-1H-1,2,4-triazol-3-yl]acetic acid ligand, a carboxyl-ate O atom of the symmetry-related ligand and the O atom of the methanol mol-ecule [U-N/Oeq 2.256 (4)-2.504 (5) Å]. The axial positions are occupied by two oxide O atoms. The equatorial atoms are almost coplanar, with the largest deviation from the mean plane being 0.121 Å for one of the O atoms. The benzene and triazole rings of the tetra-dentate chelating-bridging ligand are twisted by approximately 21.6 (2)° with respect to each other. The carboxyl-ate group of the ligand bridges two uranyl cations, forming a neutral zigzag chain reinforced by a strong O-H⋯O hydrogen bond. In the crystal, adjacent chains are linked into two-dimensional sheets parallel to the ac plane by C/N-H⋯N/O hydrogen bonding and π-π inter-actions. Further weak C-H⋯O contacts consolidate the three-dimensional supra-molecular architecture. In the solid state, the compound shows a broad medium intensity LMCT transition centred around 463 nm, which is responsible for its red colour.

(E)-2-((1,7,7-Trimethylbicyclo [2.2.1]Heptan-2-Ylidene) Amino) Acetic Acid Compound and their Metal Complexes: Synthesis and Characterization

The reaction of camphor with glycine under the showing conditions yielded (E)-2-((1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)amino)acetic acid ligand . The complexes of Cu(II), Ni(II), Co(II), Zn(II) and Fe(II) with ligand have been obtained by the reaction between copper bromide, hydrate nickel chloride, hydrate cobalt chloride, zinc chloride, and iron bromide with ligand in 1:2 mole ratio. The free ligands and their metal complexes have been separated in the solid state. The spectroscopic data of the complexes recommend their 1:2 structures which are researched by elemental analysis (CHN) 1H NMR and FT-IR spectroscopy. From the spectroscopic data proposed the octahedral structure for the all complexes.

Synthesis of Sm (III) complex immobilized in MCM-41: A new heterogeneous catalyst for the facile synthesis of 5-substituted 1H-tetrazoles via [3 + 2] cycloaddition of nitriles and sodium azide

Samarium (III) complex immobilized in MCM-41 were synthesized via post-functionalization modification of MCM-41. The catalysts were characterized by Fourier transforms infrared (FT-IR) spectra, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). The results show that the 3,4,5-tri hydroxyphenyl acetic acid ligand and Sm ions are attached to the MCM-41 host. The catalysts were tested in the synthesis of 5-substituted 1H-tetrazoles. This catalyst is an efficient catalyst for [3 + 2] cycloaddition with NaN3 to prepare 5-substituted 1H-tetrazoles. The catalyst was recycled for up to six cycles without significant loss of activity.

Spectroscopic studies, Density Functional Theory calculations, and non‐linear optical properties of binuclear Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) complexes of OONN Schiff base ligand

AbstractThe binuclear complexes of Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) with 2‐[3‐(benzylideneamino)‐2‐(benzylidenehydrazono)‐4‐oxothiazolidin‐5‐yl] acetic acid ligand (HL) were prepared and their stoichiometry was determined by elemental analysis. The stereochemistry of the studied binuclear metal complexes was confirmed by analyzing their infrared spectra, 1H NMR, and magnetic moment. Thermal decomposition studies of the binuclear complexes have been performed to demonstrate the status of water molecules present in these binuclear complexes and their general decomposition pattern. The equilibrium geometry of the ligand and its studied complexes were calculated using density function theory (DFT) calculations at the B3LYP/GENECP level of the theory. The results show that the ligand and its complexes are nonplanar structures as indicated from the values of the dihedral angles. Extent of distortion from regular geometry has been performed and discussed in terms of the values of the angles between the central metals and the coordinated sites. The EHOMO and ELUMO energies of the studied ligand and its complexes are used to calculate the global properties. The nonlinear optical parameters (NLO), anisotropy of the polarizibility (Δα), and the mean first‐order hyperpolarizability (<β>) were calculated. The (<β>) values were compared with Urea as a reference molecule and the results of (<β>) values showed that the ligand and the studied complexes have good NLO behaviors.

Characterization of holmium(iii)-acetylacetonate complexes derived from therapeutic microspheres by infrared ion spectroscopy.

Microspheres containing radioactive 166holmium-acetylacetonate are employed in emerging radionuclide therapies for the treatment of malignancies. At the molecular level, details on the coordination geometries of the Ho complexes are however elusive. Infrared ion spectroscopy (IRIS) was used to characterize several 165Ho-acetylacetonate complexes derived from non-radioactive microspheres. The coordination geometry of four distinct ionic complexes were fully assigned by comparison of their measured IR spectra with spectra calculated at the density functional theory (DFT) level. The coordination of each acetylacetonate ligand is dependent on the presence of other ligands, revealing an asymmetric chelation motif in some of the complexes. A fifth, previously unknown constituent of the microspheres was identified as a coordination complex containing an acetic acid ligand. These results pave the way for IRIS-based identification of microsphere constituents upon neutron activation of the metal center.

Syntheses and Crystal Structures of Copper(II) Bis(pyrazolyl)acetic Acid Complexes

The reaction of bis(pyrazol-1-yl)acetic acid (L) with copper(II) bromide provides two new complexes: [Cu(L-H)Br(µ-Br)]2 (1) and [Cu(L)2]⋅4H2O (2). Complex 1 is prepared by the stoichiometric reaction of L-H with copper(II) bromide in tetrahydrofuran. Dissolution of 1 in methanol causes its conversion into the bis-ligated complex (2), a highly hygroscopic material. Complex 2 can also be synthesized directly by the stoichiometric reaction of L-H with CuBr2 in methanol. Complex 1 is dimeric, interlinked by two bridging bromide ligands, and possesses terminal bromide ligands on each copper atom. The two pyrazolyl ligands in 1 coordinate with the nitrogen atoms to complete the coordination sphere of copper, resulting in a highly distorted geometry that lies between a trigonal bipyramidal or square pyramidal geometry with wide bond angles between the trans-oriented pyrazolyl nitrogen atoms and bromide ligands. Complex 2 assumes a pseudo-trigonal prismatic geometry with the deprotonated carboxylic acid that interacts weakly with copper. Reaction of bis(pyrazol-1-yl)acetic acid (L-H) with copper(II) bromide provides two new complexes: [Cu(L-H)Br(µ-Br)]2 (1) and [Cu(L)2]⋅4H2O (2), these compounds represent the first, well-defined, independent copper(II) compounds supported by the base bis(pyrazolyl)acetic acid ligand.

Zinc and cobalt complexes with (2-carboxyphenoxy) acetic acid ligand: syntheses, structures, fluorescent and magnetic properties

Four binary compounds, [Zn(cpa)(H2O)3] (1), [Co(cpa)(H2O)3] (2), [Zn(cpa)(H2O)]n, (3) and [Co(cpa)(H2O)]n (4) (H2cpa = (2-carboxyphenoxy)acetic acid), have been synthesized and structurally characterized. In mononuclear 1 or 2, the metal ion (ZnII for 1 and CoII for 2) is surrounded by three water molecules and one tridentate chelate cpa2− in a distorted octahedral geometry, while in 3 or 4, the central metal ion (ZnII for 3 and CoII for 4) is located in a deformed square–pyramid formed by one water and two cpa2−. Each cpa2− is chelate bridging μ2 coordination and forms a 1-D zigzag chain structure 2 or 3. The different synthesis conditions for 1–4 have been carefully discussed. The solid-state fluorescence measurements for 1 and 3 together with magnetic properties for 4 also have been investigated.

Synthesis and structure of mono- and polynuclear Cu(II) complexes with α-(N-benzoxazolin-2-one)acetic acid

Two compounds with the α-(N-benzoxazolin-2-one)acetic acid ligand (L) were synthesized: [Cu(L)2(NH2C2H4OH)2] (I) and [Cu(L)2(H2O)2]n (II), viz., mono- and polynuclear complexes, respectively. According to X-ray diffraction data (CIF files CCDC no. 1008795 (I) and 1008794 (II)), the coordination polyhedron of the metal atom in I is an extended tetragonal bipyramid with four heteroatoms of two monoethanolamine molecules in the equatorial plane. The carboxyl oxygen atoms of two ligands L occupy the apical positions. In complex II, a tetragonal bipyramid is also formed, having two O atoms of the carboxyl groups of the L molecule and two water O atoms in the equatorial plane. Two oxygen atoms of the carboxyl groups of the L molecule occupy apical positions. Complex II is a 2D polymer (polymerization involves four O atoms of the carboxyl group) with the [CuL2(H2O)2] unit.

Enhancement of the photovoltaic performance in P3HT: PbS hybrid solar cells using small size PbS quantum dots

Different approaches of surface modification of the quantum dots (QDs), namely, solution-phase (octylamine, octanethiol) and post-deposition (acetic acid, 1,4-benzenedithiol) ligand exchange were used in the fabrication of hybrid bulk heterojunction solar cell containing poly (3-hexylthiophene) (P3HT) and small (2.4 nm) PbS QDs. We show that replacing oleic acid by shorter chain ligands improves the figures of merit of the solar cells. This can possibly be attributed to a combination of a reduced thickness of the barrier for electron transfer and an optimized phase separation. The best results were obtained for post-deposition ligand exchange by 1,4-benzenedithiol, which improves the power conversion efficiency of solar cells based on a bulk heterojunction of lead sulfide (PbS) QDs and P3HT up to two orders of magnitude over previously reported hybrid cells based on a bulk heterojunction of P3HT:PbS QDs, where the QDs are capped by acetic acid ligands. The optimal performance was obtained for solar cells with 69 wt. % PbS QDs. Besides the ligand effects, the improvement was attributed to the formation of an energetically favorable bulk heterojunction with P3HT, when small size (2.4 nm) PbS QDs were used. Dark current density-voltage (J-V) measurements carried out on the device provided insight into the working mechanism: the comparison between the dark J-V characteristics of the bench mark system P3HT:PCBM and the P3HT:PbS blends allows us to conclude that a larger leakage current and a more efficient recombination are the major factors responsible for the larger losses in the hybrid system.

Complexes of Mn(II) with imidazole and 2-thiophene acetic acid ligands

The reactions of 2-thiophene acetic acid and imidazole with manganese (II) chloride resulted in mononuclear [Mn(C6H5O2S)2(C3H4N2)6] (1), or binuclear [Mn2(C6H5O2S)4(C3H4N2)4] (2) and [Mn2(C6H5O2S)4(C3H4N2)4(H2O)] (3) complexes. In the complex (1), the Mn ion is octahedral coordinated by six nitrogen atoms from six imidazole rings and the Mn-O bond lengths are in the range 2.261(4) to 2.275(6) Å. The crystal packing is stabilized by weak C-H...O and N-H...O hydrogen bonds. In the structure of (2), the asymmetric unit is formed from an Mn ion bonded to two N atoms from two imidazole ligands and to three O atoms from three different thiophene acetic acid ligands. Two of these ligands are deprotonated and bridge by the same oxygen atoms between the second manganese ion giving rise to an binuclear complex. In this complex, each Mn cation is located in a slightly distorted square-planar environment and the Mn-N bond lengths are in the range 1,960(3) to 1.976(2) Å. The Mn-O bonds lengths in the square base of the two pyramids are in the range 1.956(5) to 2.000(1) Å. The Mn-O axial bond distance is quite longer than the Mn-O equatorial bond distances and is 2.458(2)Å [1,2]. The crystal packing is stabilized by weak C-H...O and N-H...O hydrogen bonds forming connected layers parallel to (001) planes. When an oxygen of one molecule of water bridges the two metal centers in the complex (2), the environment of the two Mn becomes octahedral and thus we obtain the complex (3). In this latter complex, the Mn-N bonds are in the range 2.192(4) to 2.245(4). All Mn-O bonds are between 2.148(6) and 2.232(7)Å. All structures are disordered in all thiophenyl rings occupy alternatively two positions related to one another by an 180o rotation about the C–C sigma bond [3]. The sulfur and one carbon atom of the ring occupy the same position. The complexes were structurally characterized by single crystal X-ray diffraction analyses, infrared spectroscopy (IR), elemental analyses and thermogravimetric analyses (TGA). Cristal data: (1): MnC30H34N12O4S2 in C2/c, a=11.3492(6), b=13.9186(7), c=22.2101(13), beta= 94.963(4) (2): Mn2C36H36N8O8S4 in P21/n, a=15.996(2), b=10.274(13), c=26.141(3), beta=97.715(9) (3): Mn2C24H38N8O9S4 in P21/n, a=26.206(2), b=8.5421(8), c=19.0694(17), beta= 92.229(4)

Synthesis and characterization of novel transition metal complexes with indole acetic acid ligands: Evaluation of their catalytic activity for the oxidation of cyclohexane

Two new transition metal complexes Co(IAA)2(phen)(H2O) (1) and Ni(IAA)2(phen)(H2O) (2) (IAA=indole acetic acid, phen=1,10-phenanthroline) with IAA and phen as mixed ligands are synthesized and characterized by elemental analysis, IR spectra, UV–Vis spectroscopy and single-crystal X-ray diffraction. The structural analysis shows that the coordination mode of the ligand IAA in complexes 1 and 2 were similar: the former is in a μ1–η1 linking fashion, while the latter is in a μ1–η1–η1 linking fashion. In addition, the thermogravimetric analysis of the complexes was investigated in detail. The catalytic activity of the two complexes has been invested in the oxidation of cyclohexane with the presence of H2O2 as primary oxidant under mild conditions, which shows that cobalt complex with IAA ligand exhibited a good catalytic activity with the maximum TON value of 110.

Synthesis, spectroscopic, thermal and DFT calculations of 2-(3-amino-2-hydrazono-4-oxothiazolidin-5-yl) acetic acid binuclear metal complexes

The binuclear complexes of 2-(3-amino-2-hydrazono-4-oxothiazolidin-5-yl) acetic acid ligand (HL) with Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) ions were prepared and their stoichiometry was determined by elemental analysis. The stereochemistry of the studied series of metal complexes was established by analyzing their infrared, 1H NMR spectra and the magnetic moment measurements. According to the elemental analysis data, the complexes were found to have the formulae [Fe2L(H2O)8]Cl5 and [M2L(H2O)8]Cl3 (M=Co(II), Ni(II), Cu(II) and Zn(II)). The present analyses demonstrate that all metal ions coordinated to the ligand via O(9), O(11), N(16) and N(18) atoms. Thermal decomposition studies of the ligand–metal complexes have been performed to verify the status of water molecules present in these metal complexes and their general decomposition pattern. Density Functional Theory (DFT) calculations at the B3LYP/6-31G* level of theory have been carried out to investigate the equilibrium geometry of the ligand and complexes. Moreover, charge density distribution, extent of distortion from regular geometry, dipole moment and orientation have been performed and discussed.

Synthesis, spectral characterisation and cytotoxic effect of metal complexes of 2-(2-(4-carboxyphenyl)guanidino) acetic acid ligand

A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Sr(II), Hg(II), Ag(I), Tl(I) and UO2(II) complexes of 2-(2-(4-carboxyphenyl)guanidino)acetic acid ligand have been synthesised and characterised by elemental analyses, IR, UV-Vis spectra, mass spectra (ligand and its zinc(II) complex), 1H NMR spectra (ligand and its mercury(II) complex), magnetic moments, conductances, thermal analyses (DTA and TGA) and ESR measurements. The IR data show that, the ligand behaves as neutral tridentate, (2), [(H2 LL)3 CCu2 ((OAc)4 ((H2 OO)2 ] ], neutral bidentate, (3), [(H2LL)Cu(OAc)2]].1/2H2OO, (13), [(HL)2CCuCl2((H2OO)2]], (17), [(H2LL)Cu(OOSO2))(H2OO)J,dibasic hexadentate, (4), [(L) Ni4((OAc)6((H2OO)J.4H2OO, (5), [(L)Mn4(OAc)6(H2O)10]. 4H2O, (6), [(L)Co4(OAc)6(H2O)10] . 4H2O, monobasic bidentate, (7), [(HL)(UO2)(OAc)(H2O)3], (12), [(HL)2Cu], (15), [(HL)2Fe2(Cl4)(H2O)2]. 7H2O, (16), [(HL)2Cr2(Cl4)(H2O)2]. 7H2O, (21 ), [(H2L)Cd (OOSO2)(H2O)3]. 2H2O, monobasic tridentate, (8), [(L)2HHg2((OAc)2 (H2O)6].H2O, (9), [(L)2Zn2(OAc)2(H2O)6].H2O, (10), [(L) 2ZZn2((OAc)2((H2OO)6]].H2OO, (11), [(L)Tl4(OAc)3 (H2O)6], (18), [(HL)(OH)Cr2(SO4)2(H2O)5]. H2O, (19), [(HL)3Ag3NO3], or dibasic tridentate, (14), [(L) Sr(Cl)20 ((H2 OO)24 ]], (20), [(L)3 CCu (H2 OO)2 ] ]. Molar conductances in DMF indicate that, the complexes are non-electrolyte. The ESR spectra of Cu(II) complexes (2), (3) and (20) at room temperature show axial type symmetry with g// > g-> 2.00, indicating a d(x2-y2) ground state with significant covalent bond character in an octahedral or square planar geometry. However, Cu(II) complexes (12) and (13) show isotropic type, indicating square planar and octahedral structure. Complexes Mn(II) (5) and Co(II) (6) show broad signals in the low field region indicating spin exchange interaction take place between metal(II) ion. Hg(II) complex (9), Tl(I) complex (11), Cr(III) complex (16), Cu(II) complex (17) and Cd(II) complex (21) showed potential antiproliferative activity where they showed inhibitory effect on breast carcinoma (MCF-7 cell line) in comparing with the standard drug.

Dibromido[methyl 2-(quinolin-8-yloxy-κ2N,O)acetic acid-κO]mercury(II)

In the title complex, [HgBr2(C12H11NO3)], the HgII ion has a distorted core trigonal–planar geometry comprising two Br atoms and one quinoline N atom of the methyl 2-(quinolin-8-yl­oxy)acetic acid ligand. The angles around the Hg atom vary from 100.31 (15) to 152.65 (4)°. Two additional Hg⋯O inter­actions [2.739 (1) and 2.905 (1) Å] complete the coordination sphere about the HgII atom.

Diaquabis{2-[5-(2-pyridyl)-2H-tetrazol-2-yl]acetato-κ2N4,N5}zinc(II)

The title compound, [Zn(C8H6N5O2)2(H2O)2], was synthesized by hydro­thermal reaction of ZnBr2 with 2-[5-(2-pyrid­yl)-2H-tetra­zol-2-yl]acetic acid. The ZnII atom lies on an inversion center in a distorted octa­hedral environment with two planar trans-related N,N′-chelating 2-[5-(2-pyrid­yl)-2H-tetra­zol-2-yl]acetic acid ligands in the equatorial plane and two water mol­ecules in the axial positions. In the crystal, O—H⋯O hydrogen bonds generate an infinite three-dimensional network.

Di-μ-acetato-κ4O:O′-μ-oxido-κ2O:O-bis[(acetic acid-κO)bis(1H-imidazole-κN3)magnesium(II)

Magnesium acetate crystallizes upon reaction with imidazole in dimethyl­formamide at elevated temperatures to form the title magnesium acetate imidazole cluster species, [Mg2(C2H3O2)2O(C3H4N2)4(C2H4O2)2], with two Mg atoms in octa­hedral coordination. The complex has crystallographic twofold rotation symmetry. Each Mg atom is coordinated by two imidazole ligands, two linking acetate bridging ligands, a terminal acetic acid ligand, and a bridging O atom lying on the symmetry axis.

Synthesis and antimicrobial activity of silver(I) and copper(II) complexes with 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl) acetic acid

Ag(I) and Cu(II) complexes with 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl)acetic acid ligands (L) have been synthesized and characterized using a combination of methods, including x-ray powder diffraction, elemental analysis, TG/DTA, FT-IR, and EPR. The antimicrobial properties of 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl]acetic acid and its complexes with Ag(I) and Cu(II) were tested against standard E. coli, Ps. aeruginosa, C. albicans, B. subtilis, St. aureus, and Pr. vulgaris strains.

The Complex Synergy of Water in Metal/Bromide Autoxidations. Part II. Effect of Water and Catalyst on the Aerobic Oxidation of Benzaldehydes and the Effect of Water on the Elementary Catalytic Pathways

All of the rates of the elementary steps in the Co/Br and Co/Mn/Br homogeneous, liquid-phase catalyzed reactions decrease with increasing water concentration in acetic acid. The step-wise replacement of the acetic acid ligands by water ligands in the coordination sphere of the catalyst metals may be responsible for this behavior. The non-catalyzed and metal-catalyzed (Co, Co/Mn/Br and Co/Mn) aerobic oxidations of benzaldehyde and 4-methylbenzaldehyde are reported. The non-catalyzed autoxidations are quite vigorous reactions in acetic acid/water mixtures but by-products from the Baeyer-Villiger reaction, the thermal decomposition of the peroxy acid, and over-oxidation to carbon dioxide limit the yield to the aromatic carboxylic acids. As the concentration of a Co or Co/Mn/Br catalyst increases these by-products are first reduced and then eliminated probably due to the very fast, selective reaction of [Co(II)] 2 with the peroxy acid. A Co/Mn catalyst completely inhibits the autoxidation of the benzaldehydes. There is a gradual change in the yield of terephthaldicarboxaldehyde from 4-methylbenzaldehyde with increasing Co/Mn/Br concentration suggesting that the non-catalyzed steps are being replaced by catalyzed ones. The autoxidation of heptaldehyde generates about 500 times more carbon monoxide than does benzaldehyde using a Co/Mn/Br catalyst and gives only a 50% yield to heptanoic acid consistent with excessive amounts of decarbonylation with aliphatic aldehydes.

Binding of an acetic acid ligand to adenosine: a low-temperature NMR study.

Binding of an acetic acid (HAc) ligand to adenosine (A) was studied by (1)H NMR spectroscopic techniques. Using a low-melting deuterated Freon mixture as solvent, liquid-state measurements could be performed in the slow exchange regime and allowed a detailed characterization of the formed associates. Thus, at 128 K, trimolecular complexes A.HAc(2) and A(2).HAc with both Watson-Crick and Hoogsteen sites of the central adenine base occupied coexist in various amounts depending on the adenosine:acetic acid molar ratio. Whereas the carboxylic acid OH proton is located closer to the acid for all hydrogen bonds formed, a more deshielded proton at the Watson-Crick site is evidence for a stronger hydrogen bond as compared to the Hoogsteen interaction. For the binding of acetic acid to an adenosine-thymidine base pair in either a Watson-Crick or a Hoogsteen configuration, hydrogen bonds to the available adenine binding site are strengthened as compared to the corresponding hydrogen bonds in the A.HAc(2) complex.

Structural Systematics of Rare Earth Complexes. X (‘Maximally’) Hydrated Rare Earth Acetates

Extension/augmentation of preexisting work carried out in respect of room-temperature single-crystal X-ray structural characterization of trivalent rare earth acetates, crystallized as ‘maximal’ hydrates, Ln(ac)3.x H2O, from aqueous solution under local ambience, suggests the following array to be prevalent: For Ln = La(-)Pr: triclinic P 1 sesquihydrate, i.e. x = 1½, a ≈ 13·4, b ≈ 10·1, c ≈ 8·6 Å, α ≈ 75·6, β ≈ 103·8, γ ≈ 92·8°, Z = 4 mononuclear f.u., conventional R on |F| for Ln = La, Ce, here, being 0·043, 0·058 for No 3199, 4442 independent ‘observed’ (I > 3σ(I)) diffractometer reflections respectively; the complexes have the form of a two-dimensional polymer, in the ac plane, the dominant motif being a chain of lanthanoid atoms of two types linked by acetate bridges along a ... Ln(1)Ln(2)Ln(2)Ln(1)Ln(1)Ln(2) ... with further acetates cross-linking the Ln(1) in the c dimension. For Ln = (Ce(-))Nd: monoclinic P 21/c monohydrate, a ≈ 8·4, b ≈ 8·0, c ≈ 15·0 Å, β ≈ 94°, Z = 4 mononuclear f.u., for the present determinations R were 0·024, 0·044 for No 2019, 2600, the structure being a one-dimensional polymeric form with acetate bridges. For Ln = Sm(-)Lu, (i.e. implicitly with intermediate Ln): triclinic P1 tetrahydrate, a ≈ 10·4, b ≈ 9·2, c ≈ 8·8 Å, α ≈ 118, β ≈ 114, γ ≈ 92°, Z = 2 mononuclear f.u., R were 0·035, 0·030 for No 4583, 4678, the complexes being acetate-bridged dimers. It is of interest that, through the three series, the variation in the degree of hydration is not monotonic. Determinations are also recorded for a pair of crystalline compounds obtained during the attempted crystallization of europium(III) acetate hydrate from aqueous solution acidified with acetic acid (Hac), supporting their formulation as entailing the formation of mixed water/acetic acid solvates Eu(ac)3.2H2O.Hac and Eu(ac)3.H2O.2½Hac, i.e. [Eu2(ac)6(OH2)4].2Hac and [Eu2(ac)6(OH2)2(Hac)2].3Hac with common binuclear cores in which a pair of unidentate water molecule ligands in the former is replaced by a pair of unidentate acetic acid ligands in the latter with relatively minor geometrical change. The former array is rhombohedral R3, a 26·865(7), c 10·328(3) Å (hexagonal setting), Z = 9 binuclear units, isomorphous with the previously reported samarium analogue, and the latter triclinic P1, a 14·131(5), b 8·919(4), c 8·582(3) Å, α 65·41(3), β 84·72(3), γ 84·27(3)°, Z = 1 binuclear unit, R 0·046, 0·051 for No 1700, 2553. An interesting double salt, trisodium hexakis(acetato)ytterbate(III) tetrahydrate, Na3[Yb(ac)6].4H2O, is monoclinic, C2/c, a 13·139(3), b 13·936(2), c 26·030(2) Å , β 91·10(1)°, Z = 8, R 0·053 for No 3467. The eight-coordinate (YbO8) environment is comprised of oxygen atoms from a pair of O,O′-chelating and four unidentate acetate moieties.