E Bugella-Altamirano

Three new modes of adenine-copper(II) coordination: interligand interactions controlling the selective N3-, N7- and bridging μ-N3,N7metal-bonding of adenine to different N-substituted iminodiacetato-copper(II) chelates

Abstract The reaction of Cu2CO3(OH)2, various N-substituted-iminodiacetic acids [RN(CH2CO2H)2)] and adenine (AdeH) in water yields crystalline samples of mixed-ligand copper(II) complexes of formulas [Cu(A)(N7AdeH)(H2O)]·H2O (A=N-methyl- or N-ethyl-iminodiacetato(2−); compounds 1 and 2, respectively), [Cu(B)(N3AdeH)(H2O)]·H2O (B=N-benzyl- or N-(p-methylbenzyl)-iminodiacetato(2−); compounds 3 and 4, respectively) as well as [Cu4(pheida)4(μ-N3,N7AdeH)2(H2O)4]·2H2O (pheida=N-phenethyl-iminodiacetato(2−)). Crystal structures of the acid H2pheida and compounds 1–5 are reported. H2pheida acid exhibits a typical zwitterionic structure. Copper(II) compounds were also studied by TG analysis (with FT-IR study of the evolved gasses), IR, electronic and ESR spectra and magnetic susceptibility data. The N-alkyl- or N-benzyl-like-iminodiacetato(2−) ligands (A or B) give complexes with Cu(II)/(A or B)/AdeH equimolar ratio, whereas pheida yields an unexpected tetranuclear compound with a 2:2:1 Cu(II)/pheida/AdeH molar ratio. In 1 and 2 AdeH binds to the metal by N7, whereas in 3 and 4 the N3 atom is used. An unexpected bridging μ-N3,N7AdeHdicopper(II) binding mode is found in the tetra-nuclear compound 5 (without interligand π,π-stacking interactions). These AdeHCu(II) binding modes have not been referred in the literature before. The difference in AdeHCu(II) binding modes in compounds 1 or 2 and 3 or 4 is rationalised on the basis of the absence or presence of a flexible N-benzyl-like substituent in the iminodiacetato(2−) ligand skeleton, which prevents or permits the interligand π,π-stacking interactions.

Synthesis, XRD structures and properties of diaqua(iminodiacetato)copper(II), [Cu(IDA)(H2O)2], and aqua(benzimidazole)(iminodiacetato)copper(II), [Cu(IDA)(HBzIm)(H2O)]

Abstract The stoichiometric reaction of copper(II) hydroxycarbonate with iminodiacetic acid (H2IDA) in water under reduced pressure yields good crystalline samples of [Cu(IDA)(H2O)2] (compound I). Using equimolar amounts of benzimidazole (HBzIm) the above reaction produces crystals of [Cu(IDA)(HBzIm)(H2O)] (compound II). Both compounds were characterised by TG analysis (with IR study of the evolved gasses in the pyrolysis), spectral and/or magnetic properties (IR, electronic, ESR spectrum, magnetic susceptibility in the 1.8–300 K range) and single crystal X-ray diffraction. The structure of I was re-determined (final R1=0.022) and it confirms the earlier reported distorted octahedral Cu(II) coordination (type 4+1+1), the fac-terdentate chelating and bridging roles for IDA ligand, as well as the ‘polymeric’ chain structure, but with a rather different hydrogen bonding network. In compound II (final R1=0.035) the Cu(II) exhibits a square base pyramidal coordination (type 4+1) and the IDA exhibits the mer-terdentate chelating configuration observed earlier for complexes having equimolar Cu(II)/IDA/HIm or HIm-like ratio, but now with a large dihedral angle (31.3°) between basal Cu(II) coordination and HBzIm mean planes.

Structural Relationships obtained from the Coordination of α-Picolinamide to the (Iminodiacetato)copper(II) Chelate: Synthesis, Crystal Structure, and Properties of (α-Picolinamide)(iminodiacetato)copper(II) Dihydrate

Received November 11th, 1999. Abstract. The stoichiometric reaction of copper(II) hydroxy- carbonate, iminodiacetic acid (H2IDA = HN(CH2CO2H)2) and a-picolinamide (pya) in water yields crystalline samples of (a-picolinamide)(iminodiacetato)copper(II) dihydrate, (Cu(IDA)(pya)) · 2 H2 O( 1). The compound was charac- terised by thermal (TG analysis with FT-IR study of the evolved gasses), spectral (IR, electronic and ESR spectra), magnetic and single crystal X-ray diffraction methods. It crystallises in the triclinic system, space group P1, a = 8.8737(4), b = 10.23203(5), c = 15.7167(11) A ˚ , a =

Metal chelates of N-carbamoylmethyl-iminodiacetate(2−) ion: Part IV. Isostructural ternary mixed-ligand cobalt(II) and nickel(II) chelates with N-carbamoylmethyl-iminodiacetate(2−) ion, imidazole and aqua ligands. Synthesis, molecular and crystal structures and properties of [M(ADA)(Him)(H2O)]·1.5H2O (M=Co, Ni)

Abstract Stoichiometric reaction of CoCO3·Co(OH)2·2H2O, or NiCO3·2Ni(OH)2·4H2O with H2ADA and imidazole (Him) in water yields crystalline samples of compounds aqua(imidazole)(N-carbamoylmethyl-iminodiacetato)metal(II), [M(ADA)(Him)(H2O)]·1.5H2O (M=Co, compound I, dark pink; M=Ni, compound II, bluish). Single-crystal X-ray diffraction studies were carried out. Both complexes are isostructural (orthorhombic system, space group Pna2(1), Z=8). These crystals consist of slightly asymmetrical octahedral coordination units linked in a tridimensional network stabilised by hydrogen bonds where all N–H bonds of ADA and Him and probably O–H bonds of water molecules are involved. The asymmetric unit has two independent but very similar complex molecules and three water ones. Coordination bond distances for I (average in A): Co–N(amino)=2.14(1), Co–O(carboxyl)=2.06(1), Co–O(carboxyl)=2.08(1) and Co–O( amide)=2.15(1) with ADA, Co–N(Him)=2.04(1), and Co–O(aqua)=2.13(1). Coordination bond lengths for II (average in A): Ni–N(amino)=2.08(1), Ni–O(carboxyl)=2.04(1), Ni–O(carboxyl)=2.06(1) and Ni–O(amide)=2.012(1) with ADA, Ni–N(Him)=2.01(1), and Ni–O(aqua)=2.12(1). The ADA ligand acts as a tripodal tetradentate chelating one. On the basis of the octahedral structures of [Ni(ADA)(H2O)2], reported in the literature, and of the new compounds, it is concluded that there is a preference for the N(Him)donor atom to occupy the trans-position to the M–N(ADA) bond.

Metal chelates of N-carbamoylmethyl-iminodiacetate(2−) ion.: Part III. Synthesis, XRD structures and properties of N-carbamoylmethyl-iminodiacetic acid (H2ADA) and cis-diaqua(N-carbamoylmethyl-iminodiacetato)nickel(II), [Ni(ADA)(H2O)2]

Abstract N-(Carbamoylmethyl)iminodiacetic [H2ADA=H2NCOCH2N(CH2CO2H)2)] has been crystallised from water and characterised by X-ray crystallography (final value R1=0.051). This compound exhibits a zwitterionic structure (H2ADA±) whose conformation is stabilised by an intra-molecular hydrogen bond interaction between the ‘ammonium’ hydrogen atom and the O-amide atom as acceptor one. All the other polar bonds give hydrogen bonds, which link adjacent zwitterions, one of them is a rather symmetrical and linear link (170(2)°). The appropriate stoichiometric reaction of nickel(II) hydroxycarbonate, NiCO3·2Ni(OH)2·4H2O, and H2ADA in water yields crystalline, green samples of cis-diaqua(N-carbamoylmethyl-iminodiacetato)nickel(II), [Ni(ADA)(H2O)2] (I). Its single crystal X-ray diffraction study was also carried out (final R1=0.031). The crystal of complex I consists of slightly asymmetrical, octahedral coordination units linked in a three-dimensional network stabilised by hydrogen bonds where the water molecules play the most relevant role. Coordination bond distances in I (A): Ni(1)–N(1)=2.072(2), Ni(1)–O(11)=2.051(2), Ni(1)–O(21)=2.045(2) and Ni(1)–O(31, amide)=2.065(2) with ADA, and Ni(1)–O(1)=2.000(2) and Ni(1)–O(2)=2.106(2) with aqua ligands. ADA acts as tetradentate chelating ligand, which is in contrast with chelating and bridging functions for such ligand in the polymeric Cu(II) derivative, where the metal exhibits a square base pyramidal coordination (type 4+1).

Checking for the possibility of an ‘amidomethyl’ N-substituent being involved in the iminodiacetat–copper(II) chelation: synthesis, molecular and crystal structure and properties of (imidazole)(N-carbamoylmethyl-iminodiacetat)copper(II), [Cu(ADA)(ImH)]

Abstract The stoichiometric reaction of copper(II) hydroxycarbonate, N-carbamoylmethyl-iminodiacetic acid [H2ADA=H2NCOCH2N(CH2CO2H)2)], and imidazole (ImH) in water yields crystalline samples of (imidazole)(N-carbamoylmethyl-iminodiacetate)copper(II), [Cu(ADA)(ImH)] (compound I). The compound was characterized by TG analysis (with IR study of the evolved gasses) and by spectral (IR, electronic and ESR spectra) and single crystal X-ray diffraction methods. In compound I, ADA acts as a tetradentate ligand and the Cu(II) atom exhibiting a square base pyramidal coordination (type 4+1). Coordination bond distances (A): Cu(1)–N=2.040(2), Cu(1)–O(11)=1.943(2), Cu(1)–O(21)=1.964(2) and Cu(1)–O(31)=2.322(2) with ADA and Cu(1)–N(1)=1.960(2) with ImH. The tetradentate chelating role of ADA is discussed on the basis of the preference to the O(amido) donor atom (versus the N one) of ADA to occupy an axial/remote coordination position around the Cu(II) atom as well as by the expected mer-chelating configuration of the ‘Cu–iminodiacetato’ moiety (Cu–IDA) upon the imidazole–copper(II) coordination in the studied mixed-ligand complex I (having a 1:1:1 Cu/ADA/ImH molar ratio).

Structural Relationships Afforded by the Coordination of 2,2′-Bipyridine to the (Iminodiacetato)Copper(II) Chelate: Synthesis, Structure and Properties of (2,2′-Bipyridine) (N-(2-Hydroxyethyl)Iminodiacetato) Copper(II)Tetrahydrate

Abstract The stoichiometric reaction of copper(II) hydroxycarbonate, N-(2-hydroxyethyl)iminodiacetic acid [H2heida˭HOCH2CH2N(CH2CO2H)2)] and 2,2′-bipyridine (bipy) in water yields crystalline (2,2′-bipyridine)(N-(2-hydroxyethyl)iminodiacetato)copper(II) tetrahydrate, [Cu(heida)-(bipy)] · 4H2O (compound I). This was studied by TG analysis (with FT-IR study of evolved gases), IR, electronic and ESR spectra, magnetic susceptibility data and single crystal X-ray diffraction methods. The compound crystallises in the triclinic system, space group P1, a = 7.011(2), b = 12.586(3), c = 13.052(3) Å, α = 62.14(1), β = 80.51(2), γ = 77.09(2)°, Z = 2, final R 1 = 0.051 for 3900 independent reflections. The Cu(II) atom exhibits an asymmetric, elongated, octahedral coordination (type 4+1 + 1), and bipy acts as an N,N-bidentate ligand supplying two among the four closest donor atoms of the metal (Cu-N bond lengths of 1.994(2) and 2.053(2) Å); heida plays an N,O,O′,O″-tetradentate chelating role (bond lengths Cu‒N = 2.075(2), Cu-O(carboxyl) = 1.958(2), Cu-O′(carboxyl) = 2.337(2) and Cu-O″(hydroxyl) = 2.459(2) Å). The effective bidentate chelation of bipy imposes fac-chelation to the iminodiace-tate moiety of heida in I, as previously reported in mixed-ligand complexes having a 1:1:2 Cu(II)/IDA/N(heterocyclic) or a 1/1/(1 + 1) Cu/IDA/(N-heterocyclic + N-aliphatic) donor ratio. The tetradentate role of heida in I reveals its noticeable conformational flexibility. The crystal features a hydrogen bond network forming supra-molecular chains extending along the a axis. These are linked by two symmetry-related hydrogen bonds of the type O(hydroxyl)-H…O′(carboxyl) between two adjacent complex units (symmetry code i=-x, -y+1, -z+1), related to each other by an inversion centre.

Synthesis, Structure and Properties of Poly > [(N-(2-Hydroxyethyl)- N'-carboxymethyl-1,2-ethylenediamine-N, N'-Diacetato)copper(II) Hydrate], {[Cu(Hhedta)] · H2O }n

Abstract The stoichiometric reaction of N-(2-hydroxyethyl)-1,2-ethylenediamine-N,N,N′-triacetic acid [H3hedta = (HOCH2CH2)(HO2CCH2)NC2H4N(CH2CO2H)2)] and copper(II) hydroxy-carbonate in water yields crystalline samples of poly-{(N-(2-hydroxyethyl)-N′-carboxymethyl-1,2-ethylenediamine-N,N′-diacetato)copper(II) hydrate}, {[Cu(Hhedta)] · H2O}n (I)-The compound was studied by TG analysis (with FT-IR study of the evolved gases), IR, electronic and ESR spectra, magnetic susceptibility data and single crystal X-ray diffraction methods. It crystallises in the orthorhombic system, space group Fdd2 (a = 21.906(2), b = 36.602(4), c = 6.928(1) Å, Z = 16, and final R1 = 0.029 for 1554 independent reflections). The Cu(II) atom exhibits a very distorted octahedral coordination (type 4+1 + 1). The Hhedta ligand plays a N,N′,O,O′O″-pentadentate chelating role as well as a O,O′-carboxylate bridging one and has a free N-carboxymethyl arm. The bridging carboxylate group of the Hhedta ligand leads to polymeric chains {[Cu(Hhedta)] · H2O}n parallel the c axis. A hydrogen bonding network involves all O-H polar bonds (non-ionised carboxylic and alcoholic hydroxyl groups and water molecules). The structure reveals the preferred formation of a copper(II)-(N-2-hydroxyethyl-amino) or copper(II)-(ethanolamino) versus a copper(II)-(N-carboxymethylamino) chelate ring.