A novel [Cu II 4] cluster from the assembly of two [Cu II 2L]+ units by a central mu4-1,1,2,2 perchlorate ligand

A perchlorate ligand in the rare mu4-1,1,2,2 binding mode is seen for the first time as the sole support for the assembly of two cationic [Cu II 2L]+ fragments (H3L = a dinucleating ligand) in the formation of a magnetically-exchanged tetranuclear cluster.     

Structure and magnetic properties of Pb2Cu3B4O11: a new copper borate featuring [Cu3O8]10- units

Pb2Cu3B4O11 crystallizes in the monoclinic space group P2/n (No. 13) with a = 6.8016(15) A, b = 4.7123(10) A, c = 14.614(3) A, beta = 97.089(3) degrees, and Z = 2. The crystal structure consists of infinite [Cu3O8]10- zigzag chains of alternating dimers and monomers. The magnetic susceptibility and specific heat capacity show spin-gap and Curie-Weiss behaviors that can be explained by a model of Cu(2)-Cu(2) dimers and isolated or weakly coupled Cu(1) monomers.     

Synthesis, reactivity and structural characterization of ytterbium complexes bearing a tridentate [O,N,N] Schiff base ligand

The synthesis, characterization and reactivity of ytterbium monochloride supported by tridentate Schiff base ligands are described. The metathesis reaction of anhydrous YbCl₃ with 1 equivalent of the sodium salt of a Schiff base, [{LNa(THF)}₂] (1) [LH = 3,5-Bu^t₂-2-(OH)-C₆H₂CHN-8-C₉H₆N], gave the ytterbium Schiff base monochloride complex L₂YbCl (2). Complex 2 reacted with NaOAr (OAr = OC₆H₃Bu^t-2-Me-4) in a 1:1 molar ratio to form the desired aryloxo derivative L₂Yb(OAr) (3). Complex 3 can also be prepared by the one-pot reaction of the Schiff base HL, n-BuLi, YbCl₃ and NaOAr in a 2:2:1:1 molar ratio. However, an unprecedented ytterbium aryloxide LL′Yb(OAr) (4) (L′ = 3,5-Bu^t₂-2-(O)C₆H₂CH(C₄H₉)-NH-8-C₉H₆N) can be isolated in low yield as a byproduct in the later case. Reaction of complex 2 with 1 equivalent of (CH₂CH-CH₂)MgBr in THF afforded the unexpected complex [Mg(H₂N-8-C₉H₆N)Cl(THF)₃]Br (5). Complexes 2-5 were fully characterized by elemental analysis and X-ray diffraction.     

Synthesis and structures of aluminium monohydride and chalcogenides bearing a bidentate [N,O] ligand

The aluminium monohydride (3-tBu-5-Me-2-(O)C(6)H(2)CH(2)-N-2,6-iPr(2)C(6)H(3))AlH(NMe(3))(2) was prepared by treatment of the bidentate salicylaldimine [3-tBu-5-Me-2-(OH)C(6)H(2)CH=N-2,6-iPr(2)C(6)H(3)](1) with a small excess of AlH(3).NMe(3) in high yield. Compound 2 reacted with sulfur and selenium respectively to afford the dimeric aluminium chalcogenide [(3-tBu-5-Me-2-(O)C(6)H(2)CH(2)-NH-2,6-iPr(2)C(6)H(3))Al(micro-E)](2)[E = S (3), E = Se (4)]. During the formation of 2 hydrogen migration from the aluminium centre to the ligand backbone occurred. A possible reaction mechanism for 3 and 4 is discussed and the molecular structures of compounds 2-4 were determined by X-ray structural analyses.     

Syntheses, X-ray crystal structures, and magnetic properties of novel linear M2[II]U[IV] complexes (M=Co, Ni, Cu, Zn)

Attempts to prepare heterobimetallic complexes in which 3d and uranium magnetic ions are associated by means of the Schiff bases H(2)L(i) derived from 2-hydroxybenzaldehyde or 2-hydroxy-3-methoxybenzaldehyde were unsuccessful because of ligand transfer reactions between [ML(i)] (M=Co, Ni, Cu) and UCl(4) that led to the mononuclear Schiff base complexes of uranium [UL(i)Cl(2)]. The crystal structure of [UL(3)Cl(2)(py)(2)] [L(3)=N,N'-bis(3-methoxysalicylidene)-ethylenediamine; py=pyridine] was determined. The hexadentate Schiff base ligand N,N'-bis(3-hydroxysalicylidene)-2,2-dimethyl-1,3-propanediamine (L) was useful for the synthesis of novel trinuclear complexes of the general formula [[ML(py)](2)U] (M=Co, Ni, Zn) or [[CuL(py)]M'[CuL]] (M'=U, Th, Zr) by reaction of [M(H(2)L)] with [M'(acac)(4)] (acac=MeCOCHCOMe). The crystal structures of the Co(2)U, Ni(2)U, Zn(2)U, Cu(2)U, and Cu(2)Th complexes show that the two ML fragments are orthogonal, being linked to the central actinide ion by the two pairs of oxygen atoms of the Schiff base ligand. In each compound, the UO(8) core exhibits the same dodecahedral geometry, and the three metals are linear. The magnetic study indicated that the two Cu(2+) ions are not coupled in the Cu(2)Zr and Cu(2)Th compounds. The magnetic behavior of the Co(2)U, Ni(2)U, and Cu(2)U complexes was compared with that of the Zn(2)U derivative, in which the paramagnetic 3d ion was replaced with the diamagnetic Zn(2+) ion. A weak antiferromagnetic coupling was observed between the Ni(2+) and the U(4+) ions, while a ferromagnetic interaction was revealed between the Cu(2+) and U(4+) ions.     

Metal-driven ligand assembly in the synthesis of cyclodextrin [2] and [3]rotaxanes

Cyclodextrin [2] and [3]rotaxanes have been synthesised by use of a metal-driven ligand formation methodology. The kinetically stable cobalt(III) complexes formed act as either linking or capping groups, the function being selected by manipulation of the reaction conditions to promote the formation of either 2:1 or 1:1 complexes, respectively. In all cases, mixtures of isomers containing different alpha-cyclodextrin orientations were observed. All three orientational isomers of the [3]rotaxane were isolated and structurally characterized by 2D NMR.     

Complexes of N-thiophosphorylthioureas (HL) with copper(I). Crystal structures of [Cu3L3] and [Cu(PPh3)2L] chelates

Reaction of the potassium salts of N-thiophosphorylated thioureas of common formula RC(S)NHP(S)(OiPr)(2) [R = morpholin-N-yl (HL(a)), piperidin-N-yl (HL(b)), NH(2) (HL(c)), PhCH(2)NH (HL(d))] with Cu(PPh(3))(3)I in aqueous EtOH/CH(2)Cl(2) leads to mononuclear [Cu(PPh(3))(2)L-S,S'] complexes. Using copper(i) iodide instead of Cu(PPh(3))(3)I, polynuclear complexes [Cu(n)(L-S,S')(n)] were obtained. The structures of these compounds were investigated by ES-MS, elemental analyses, 1H and 31P NMR in solution, IR and 31P solid-state MAS NMR spectroscopy. The crystal structures of [Cu(3)L(3)(a)] and [Cu(PPh(3))(2)L(b)] were determined by single-crystal X-ray diffraction.     

A family of new glutarate compounds: synthesis, crystal structures of: Co(H2O)5L(1), Na2[CoL2] (2), Na2[L(H2L)4/2] (3), {[Co3(H2O)6L2](HL)2}.4H2O (4), {[Co3(H2O)6L2](HL)2}.10H2O (5), {[Co3(H2O)6L2]L2/2}.4H2O (6), and Na2{[Co3(H2O)2]L8/2].6H2O (7), and magnetic properties of 1 and 2 with H2L = HOOC-(CH2)3-COOH

Seven new glutaric acid complexes, Co(H 2O) 5L 1, Na 2[CoL 2] 2, Na 2[L(H 2L) 4/2] 3, {[Co 3(H 2O) 6L 2](HL) 2}.4H 2O 4, {[Co 3(H 2O) 6L 2](HL) 2}.10H 2O 5, {[Co 3(H 2O) 6L 2]L 2/2}.4H 2O 6, and Na 2{[Co 3(H 2O) 2]L 8/2].6H 2O 7 were obtained and characterized by single-crystal X-ray diffraction methods along with elemental analyses, IR spectroscopic and magnetic measurements (for 1 and 2). The [Co(H 2O) 5L] complex molecules in 1 are assembled into a three-dimensional supramolecular architecture based on intermolecular hydrogen bonds. Compound 2 consists of the Na (+) cations and the necklace-like glutarato doubly bridged [ C o L 4 / 2 ] 2 - infinity 1 anionic chains, and 3 is composed of the Na (+) cations and the anionic hydrogen bonded ladder-like [ L ( H 2 L ) 4 / 2 ] 2 - infinity 1 anionic chains. The trinuclear {[Co 3(H 2O) 6L 2](HL) 2} complex molecules with edge-shared linear trioctahedral [Co 3(H 2O) 6L 2] (2+) cluster cores in 4 and 5 are hydrogen bonded into two-dimensional (2D) networks. The edge-shared linear trioctahedral [Co 3(H 2O) 6L 2] (2+) cluster cores in 6 are bridged by glutarato ligands to generate one-dimensional (1D) chains, which are then assembled via interchain hydrogen bonds into 2D supramolecular networks. The corner-shared linear [Co 3O 16] trioctahedra in 7 are quaternate bridged by glutarato ligands to form 1D band-like anionic {[Co 3(H 2O) 2]L 8/2} (2+) chains, which are assembled via interchain hydrogen bonds into 2D layers, and between them are sandwiched the Na (+) cations. The magnetic behaviors of 1 and 2 obey the Curie-Weiss law with chi m = C/( T - Theta) with the Curie constant C = 3.012(8) cm (3) x mol (-1) x K and the Weiss constant Theta = -9.4(7) K for 1, as well as C = 2.40(1) cm (3) x mol (-1) x K and Theta = -2.10(5) K for 2, indicating weak antiferromagnetic interactions between the Co(II) ions.     

Crystal structures and antibacterial properties of Cu(II) complexes containing an unsymmetrical N2O Schiff base ligand and bidentate N-donor heterocyclic co-ligands

Abstract

Three new Cu(II) Schiff base complexes with bidentate N-donor heterocyclic co-ligands, 2,2'-bipyridine (1), 1,10-phenanthroline (2), and 2,9-dimethyl-1,10-phenanthroline (3), were synthesized and characterized by FT-IR and UV-vis spectroscopy. Molecular structures of [C₂₀H₂₁CuN₄O](ClO₄) (1) and [C₂₄H₂₅CuN₄O](ClO₄) (3) were characterized by single-crystal X-ray crystallography. The Schiff base ligand is an N₂O-type ligand, which is the mono-condensed form of the reaction between 1,3-propanediamine and salicylaldehyde. The antibacterial activities of these complexes were investigated against one gram positive and four gram negative bacteria. Considerable antibacterial activity was obtained against both gram type bacteria. Complexes 2 and 3 with 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline, respectively, showed better antibacterial activity compared to 1 which has the 2,2'-bipyridine co-ligand.     

Synthesis,structures and Hirshfeld surface analysis of Ni(II) and Co(III) complexes with N2O donor Schiff base ligand

Two octahedral complexes [NiL(HL)]ClO₄.0.5CH₃OH and [CoL₂]ClO₄ have been synthesized with N₂O donor Schiff base ligand {((2-(phenylamino)ethyl)imino)methyl}phenol (HL) and characterized by spectroscopic techniques and single crystal X-ray diffraction studies. The molar conductivities data of the two complexes show that the complexes are 1:1 electrolyte. Single crystal X-ray diffraction data shows both Ni(II) and Co(III) complexes have distorted octahedral geometry and two ligands are coordinated to the metal centers and one ClO₄⁻ ion outside the coordination sphere. The intermolecular interactions in the complexes are evaluated by Hirshfeld surface analysis and revealed a significant contribution of non- or weakly polar interactions to the packing forces for both molecules, with crystal structure of Co(III) complex featuring short H/H contacts.     

Crystal structure of [1,4-bis[1-(3,5-dichlorophenolato-2-ylmethyl)-ylpropylamino-kappa2N,O]piperazine-kappa2N,N']cobalt(II).

The X-ray crystal structure of the title complex, Co(Cl2bprpi) is described. In this complex the Co(II) center displays a distorted octahedral coordination geometry. The piperazine ring exhibits boat conformation, forming chelate rings and capping the Co atom. The N2-Col-N3 angle is 69.41(15) degrees, extremely smaller than 90 degrees. Because the small angle causes a large steric hindrance, the piperazine ring can be effective as an ion size-recognition site. The molecular structure is stabilized by intramolecular N-H...O hydrogen bonds and Cl...H contacts.     

Crystal structure and magnetic properties of a new polymer [Cu(PzdcH)2·2H2O]n

Two different products are obtained when 2,3-pyrazinedicarboxylic acid (PzdcH₂) reacts separately with two copper(II) salts: Cu(OAc)₂ and CuCl₂. One product is a mononuclear Cu^II complex Cu(PzdcH)₂·2H₂O, the other is a linear polymeric copper(II) complex [Cu(PzdcH)₂·2H₂O]_n, whose structure has been determined by X-ray diffraction at room temperature. The polymeric complex is composed of copper(II) ions, PzdcH^- anions and crystal water molecules. The Cu(1) atom is located in elongated octahedral coordination environment with six donor atoms: O(1), N(1), O(1a), N(1a), O(3b) and O(3c) from four different PzdcH^- anions. The two oxygen atoms O(3b) and O(3c) come from the carboxylic acid group of the PzdcH^- anion of the upper and lower layers, so that an infinite chain constitutes the crystal lattice. There are very strong hydrogen bond interactions between chains which lead to a three-dimensional structure. The magnetic susceptibility of the polymeric complex [Cu(PzdcH)₂·2H₂O]_n has been determined in the 1.5–300K range. A study of magnetic properties shows that a weak antiferromagnetic interaction exists between two copper(II) ions.