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A new hetero-metallic polyoxovanadate ({Na(H2O)3}2(μ2-H2O)4{Cu(H2O)4}2[V10O28])·2H2O (1) has been isolated by refluxing a mixture containing an aqueous solution of CuCl2 and sodium meta-vanadate at acidic condition (pH ~3.4). The Infra-Red spectroscopies along with TGA and SEM analysis have been performed in order to characterize the isolated complex. Besides, the single crystal X-Ray analysis has been carried out to determine the crystal structure of 1. The crystal structure determination from the X-ray analysis reveals that the resulting POM has a 2D layer network which is produced from the interconnection of one-dimensional chains through the sodium salt of Cu(II) associated decavanadate via O atom of decavanadate with in crystallographic 'ab' plane. The complex shows good catalytic activity towards the acetylation of ortho phenylenediamine (O-PDA) and its derivatives at usual reaction conditions. [ABSTRACT FROM AUTHOR]

A nickel(II)–zinc(II) complex, [(NiL)Zn(μ1,3-NCS)2]n (1), and a nickel(II)–mercury(II) complex, [{(NiL)Hg(μ1,3-SCN)(SCN)}2] (2), (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine) were synthesized via a metalloligand approach, in which the former is a 2D coordination polymer and the latter is a discrete tetramer. Single-crystal X-ray crystallography revealed that Zn(II) in 1 and Hg(II) in 2 are in a four-coordinated distorted tetrahedral environment whereas the geometry of the Ni(II) centre is distorted octahedral for complex 1 but distorted square planar for complex 2. DFT calculations were used to analyze an intramolecular weak interaction between the square planar Ni(II) ion and the N-end of thiocyanate ions, which can be defined as a π-hole interaction. Moreover, we analyzed the tetranuclear structure of 2 in terms of a self-assembled dimer via the formation of two strong spodium bonds instead of Hg–N coordination bonds, as evidenced by the QTAIM and NCI plot analysis and the magnitude of the dimerization energy. [ABSTRACT FROM AUTHOR]

Three new trinuclear hetero-metallic complexes [(CuL)2Zn(NCS)2] (1), [(CuLR)2Zn(NCS)(μ1,1-NCS)] (2) and [(CuLR)2Cd(μ1,3-NCS)2] (4) have been synthesized using [CuL] and [CuLR] as “metalloligands” (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine and H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine). All three complexes are characterized by elemental analysis, spectroscopic methods and single crystal XRD. Complex 1 is an angular trinuclear species, in which two terminal four-coordinate square planar “metalloligands” [CuL] are coordinated to a central Zn(ii) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal isothiocyanate ions as is usually found in such complexes. In contrast, in complex 2, the two terminal “metalloligands” [CuLR] are square pyramidal, as one of the SCN− ions makes an unusual μ1,1-NCS bridge between copper centers while the other one coordinates to Zn(ii) through a N atom in a usual fashion making its geometry also square pyramidal. For 4 which possesses an angular trinuclear structure, in addition to double phenoxido bridges from two terminal [CuLR], both the SCN− ions are S-bonded to Cd(ii) and form a bridge (cis-μ1,3-SCN) between Cd(ii) and each of the terminal Cu(ii) ions. This structure is different from its unreduced analogue in which NCS− was N-terminal coordinated to Cd(ii) (3/3′). All the structures have been optimized using density functional theory (DFT) calculations. It has been found that for H2L, optimized structures like 1 and 2 differ only by 0.4 kcal mol−1 but the H2LR structure 2 is more stable by 5.5 kcal mol−1 than the structure resembling 1. For Cd(ii) complexes also, H2L optimized structures such as 3 and 4 do not differ significantly in energy (1.0 kcal mol−1) but the H2LR structure 4 is more stable than that of 3 by 4.6 kcal mol−1. In fact, structure 4 has been found to be the most stable one among the other possible isomers of H2LR. [ABSTRACT FROM AUTHOR]

Three new 2D coordination polymers (CPs) 2 ∞[(NiL)2Ni(μ1,5-N(CN)2)2]n (1), 2 ∞[(NiL)2Cd(μ1,5-N(CN)2)2]n (2) and 2 ∞[(NiL)2Zn(μ1,5-N(CN)2)2]n (3) have been synthesized by reacting a [NiL] ''metalloligand'' (where H2L = N,N'-bis(salicylidene)-1,3-propanediamine) with three different metal(II) (Ni, Cd and Zn) perchlorates and sodium dicyanamide, with identical molar ratios of the reactants. All three products have been characterized by IR and UV-Vis spectroscopies, elemental analyses, powder and single crystal X-ray diffraction and variable temperature magnetic measurements. The isomorphous compounds 1 and 2 consist of similar [(NiL)2M(μ1,5-N(CN)2)] (M = Ni for 1 and Cd for 2) angular trinuclear units in which two terminal ''metalloligands'' [NiL] coordinate to the central nickel(II) (in 1) or cadmium(II) (in 2) ion through phenoxido oxygen atoms. The μ1,5-bridging dicyanamid spacers connect the central Ni(II) or Cd(II) of one node to terminal Ni(II) of two different nodes giving rise to 2D CPs. Compound 3 also contains trinuclear units with the same formula as those of 1 and 2: [(NiL)2M(μ1,5-N(CN)2)] (M = Zn in 3). The main differences are that these units are linear in 3 and the dicyanamide spacers link only the nickel atoms of neighbouring nodes. As in 1 and 2, these trinuclear units are connected to four other units via four μ1,5-bridging dicyanamido ligands, giving rise to 2D CP with a similar topology: a uninodal 4-connected underlying net with the sql (Shubnikov tetragonal plane net) topology and (44·62) point symbol. The magnetic properties show the presence of moderate intra-trimer antiferromagnetic interactions in 1 (J = -12.9 cm-1) and weak antiferromagnetic interactions between the terminal Ni(II) ions in 2 (J = -2.4 cm-1). In 3 the Ni(II) ions are well isolated by the central Zn(II) ion and accordingly, only a very weak antiferromagnetic interaction through the single μ1,5-bridging dicyanamido ligands is observed (J = -0.44 cm-1, D = -3.9 cm-1). [ABSTRACT FROM AUTHOR]

Three new hetero-metallic Cu(II)-Zn(II) compounds [(CuL1)2Zn(N(CN)2)2] (1), 2 ∞[(CuL2)2Zn(μ1-5-N(CN)2)2]n (2A) and 1 ∞[(CuL2)2Zn(μ1-5-N(CN)2)2]n (2B) have been synthesized by reacting a [CuL1] or [CuL2] "metalloligand" (where H2L1 = N,N'-bis(α-methylsalicylidene)-1,3-propanediamine and H2L1 = N,N'- bis(salicylidene)-1,3-propanediamine) with zinc perchlorate hexahydrate and sodium dicyanamide, using various molar ratios of the reactants. All three products have been characterized by IR and UV-Vis spectroscopies, ESI-MS, elemental, powder and single crystal X-ray diffraction analyses. Complex 1 is a discrete 0D trinuclear species in which two "metalloligands" coordinate to a zinc(II) ion through phenoxido oxygen atoms along with two terminal dicyanamido ligands. In contrast, products 2A and 2B are 2D and 3D coordination polymers, respectively, which bear a common [(CuL2)2Zn(N(CN)2)2] trinuclear unit wherein, however, dicyanamido moieties adopt a μ1-5-bridging coordination mode. The coordination networks have been formed via the linkage, in different manners, of the trinuclear nodes [(CuL2)2Zn]2+ through Zn and Cu centres with the help of divergent dicyanamido spacers. These two isomeric coordination polymers represent a rare example of "genuine supramolecular isomerism". The coordination networks in 2A and 2B have been classified from the topological viewpoint, revealing a binodal 3,4-connected underlying net with the 3,4L21 topology in 2A and a uninodal 4-connected underlying net with the qtz (quartz, 4/6/h1) topology in 2B. Electronic spectra and ESI mass spectra show that all three complexes lose their solid state identity in solution. [ABSTRACT FROM AUTHOR]

A new homometallic trinuclear Ni(II) complex [(NiL)2Ni(NCS)2] (1) and three heterometallic trinuclear Ni(II)-Zn(II)-Ni(II) complexes [(NiL)2Zn(NCS)2] (2), [(NiL)2Zn(NCS)2(CH3OH)2]·2CH3OH (3) and {[(NiL)2Zn(NCS)2(CH3OH)2]} {[(NiL)2Zn(NCS)2]} (4) have been synthesized by using the "complex as ligand" approach with the "metalloligand" [NiL] (H2L = N,N'-bis(salicylidene)-1,3-propanediamine) and thiocyanate in different ratios. All the complexes have been structurally and magnetically characterized. In the isomorphous complexes 1 and 2, the two terminal square planar Ni atoms and the central octahedral nickel atom (in 1) or zinc atom (in 2) are arranged in a bent structure where two cis ?N-SCN- thiocyanate ions are coordinated to the central atom. The chemical composition of 3 is very similar to that of 2 but, in 3, the central Zn atom is tetrahedral and the ?N-SCN- thiocyanate ions occupy an axial position of each terminal nickel atom (which now are octahedral with the sixth position occupied by a methanol molecule). Complex 4 consists of two closely related trinuclear units 4A and 4B. In 4A, the coordination environments of the metals are identical to those of 3 whereas 4B is a "coordination position isomer" of complex 2 with the central square pyramidal Zn and one of the terminal square pyramidal Ni atoms coordinated by two ?N-SCN- thiocyanate ions. Complex 4 is a unique example of a cocrystal formed by two similar trinuclear units (4A and 4B) where 4A is identical to an existing complex (3) and 4B is a "coordination position isomer" of another existing complex (2). [ABSTRACT FROM AUTHOR]

Four new hetero-metallic copper(ii)–cadmium(ii) complexes [{(CuL)2Cd}2(μ1,5-N(CN)2)2](ClO4)2·(H2O)2 (1), {[{(CuL)2Cd}2(μ1,3,5-N(CN)2)2](ClO4)2}n (2), {[(CuL)2Cd(μ1,5-N(CN)2)](ClO4)}n (3) and [(CuL)2Cd(μ1,5-N(CN)2)2]n (4) have been synthesized using a trinuclear hetero-metallic node, [(CuL)2Cd]2+ (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine) and a dicyanamido spacer by varying the ratios of the reactants and temperature. The hetero-trinuclear node is formed in situ by the reaction of the “metalloligand” [CuL], cadmium perchlorate and sodium dicyanamide. All the complexes are structurally characterized. Complex 1 is a discrete hexanuclear cluster where two trinuclear nodes are connected through the Cd centres by convergent double μ1,5-dicyanamido spacers. Complex 2 is a 1D stair coordination polymer, in which the hexanuclear units are joined by the coordination of the central nitrogen atom of a μ1,3,5-dicyanamido ligand to the Cu atom of another unit. In contrast, complex 3 is a 1D zigzag chain, formed by connecting the Cd centre of trinuclear nodes via divergent μ−l,5-dicyanamido spacers. These three complexes contain a common [(CuL)2Cd(N(CN)2)]ClO4 trinuclear unit as the molecular building block. They represent an example of “supramolecular isomerism” of 0D/1D coordination polymers. On the other hand, replacement of the perchlorate ions from this trinuclear unit by another dicyanamido spacer results in complex 4, which is a 3D network, constructed by joining the trinuclear nodes through both Cd and Cu centers with the help of divergent dicyanamido spacers in the μ−l,5 mode. [ABSTRACT FROM AUTHOR]

Abstract: Three new trinuclear hetero-metallic copper(II)–cadmium(II) complexes [(CuL)2Cd (NCS)2] (1A and 1B), [(CuL)2Cd(NCO)2] (2) have been synthesized using [CuL] as so-called “ligand complex” (where H2L= N,N′-bis(salicylidene)-1,3-propanediamine) and structurally characterized. Crystal structure analyses reveal that all three complexes have trinuclear entity in which two square planar [CuL] units are bonded to a cadmium ion through double phenoxido bridges. The Cd(II) is in a six-coordinate distorted octahedral environment being bonded additionally to two mutually cis nitrogen atoms of terminal thiocyanate (in 1A and 1B) and cyanate (in 2). Complexes 1A and 1B have the same molecular formula but crystallize in different monoclinic unit cells (P21/c for 1A and P21/n for 1B) and can be considered as polymorphs. On the other hand, complex 2 is crystallized only in one form and its conformation is similar to that observed in 1A. A theoretical investigation shows that 1A is slightly more (2.25kcal/mol) stable than 1B. However, in the crystal lattice, 1A establishes a C–H/π interaction while 1B interacts through a C–H···S hydrogen bond to form dimer and the more favorable dimerization energy in the later (ca. 3kcal/mol) compensates the difference in the relative energy of the polymorphs. Complex 2 crystallizes only in one form and conformation of the molecule is similar to 1A. Analyses of the noncovalent interactions of 2 show a weakening of the dimerization energy compared to 1A or 1B. Moreover, the H-bonding interaction that facilitates the formation of 1B is unlikely to be established in 2. Therefore this polymorph is not isolated. [Copyright &y& Elsevier]

Two new heterometallic copper(II)--mercury(II) complexes [(CuL)Hg(N3)2]n (1) and [(CuL)2Hg(N3)2] (2) and one copper(II)-cadmium(II) complex [(CuL)2Cd(N3)2] (3) have been synthesized using "metalloligand" [CuL] (where H2L = N,N'-bis(salicylidene)-l,3-propanediamine) and structurally characterized. Complex 1 is a one-dimensional (ID) helical coordination polymer constructed by the joining of the dinuclear [(CuL)Hg(N3)2] units through a single μ11 azido bridge. In the dinuclear unit the Hg(II) is bonded with two phenoxido oxygen atoms of "metalloligand" [CuL] and two nitrogen atoms of azido ligands. Complex 2 is a linear trinuclear entity, in which two terminal "metalloligands" [CuL] are coordinated to central Hg(II) through double phenoxido bridges. The azido ligands link the central mercury atom with the terminal copper atoms via μ1,3bridges. In contrast, the trinuclear complex 3 is bent. Here, in addition to two double phenoxido bridges, central Cd(II) is bonded to two mutually as nitrogen atoms of two terminal azido ligands. The variation in the coordination modes of the azido ligand seems to be responsible for the different molecular shapes of 2 and 3. Interestingly, bond distances between the Hg atoms and the central nitrogen atom of the azido ligands are 2.790(4) and 2.816(5) Á in 1 and 2.823(4) Á in 2. These bond distances are significantly less than the sum of van der Waals radii of mercury (2.04 Á) and nitrogen (1.55 Á) and considerably longer than the sum of their covalent radii (2.03 Â). However the distances are similar to reported Hg--N bond distances of some Hg(II) complexes. Therefore, we have performed a theoretical density functional theory study to know whether there is any interaction between the central nitrogen atom of the azido ligand and the mercury atoms. We have used the Bader's "atoms-in-molecules", energetic and orbital analyses to conclude that such interaction does not exist The probable reason for different molecular shapes observed in trinuclear complexes of 2 and 3 also has been studied and explained by theoretical calculations and using the CSD. Electronic spectra, EPR spectra and ESI mass spectra show that all three complexes lose their solid state identity in solution. [ABSTRACT FROM AUTHOR]

A new homometallic trinuclear Ni(II) complex [(NiL)2Ni(NCS)2] (1) and three heterometallic trinuclear Ni(II)-Zn(II)-Ni(II) complexes [(NiL)2Zn(NCS)2] (2), [(NiL)2Zn(NCS)2(CH3OH)2]·2CH3OH (3) and {[(NiL)2Zn(NCS)2(CH3OH)2]} {[(NiL)2Zn(NCS)2]} (4) have been synthesized by using the "complex as ligand" approach with the "metalloligand" [NiL] (H2L = N,N'-bis(salicylidene)-1,3-propanediamine) and thiocyanate in different ratios. All the complexes have been structurally and magnetically characterized. In the isomorphous complexes 1 and 2, the two terminal square planar Ni atoms and the central octahedral nickel atom (in 1) or zinc atom (in 2) are arranged in a bent structure where two cis κN-SCN(-) thiocyanate ions are coordinated to the central atom. The chemical composition of 3 is very similar to that of 2 but, in 3, the central Zn atom is tetrahedral and the κN-SCN(-) thiocyanate ions occupy an axial position of each terminal nickel atom (which now are octahedral with the sixth position occupied by a methanol molecule). Complex 4 consists of two closely related trinuclear units 4A and 4B. In 4A, the coordination environments of the metals are identical to those of 3 whereas 4B is a "coordination position isomer" of complex 2 with the central square pyramidal Zn and one of the terminal square pyramidal Ni atoms coordinated by two κN-SCN(-) thiocyanate ions. Complex 4 is a unique example of a cocrystal formed by two similar trinuclear units (4A and 4B) where 4A is identical to an existing complex (3) and 4B is a "coordination position isomer" of another existing complex (2).