Two triangular tri-nuclear, hetero-metallic copper(II)-nickel(II) complexes, [(CuL)(2)Ni(N(CN)(2))(2)]center dot H2O (I) and [(CuL)(2)Ni(NCS)(2)]center dot H2O (2) have been synthesized by reacting "ligand complex" [CuL] with Ni(ClO4)(2) in presence of polyatomic anions, dicyanamide (dca) or thiocyanate in methanol-water medium, where H2L is a N2O2 donor di-Schiff base derived from 1,3-propanediamine and 2-hydroxyacetophenone. Both the complexes have been structurally and magnetically characterized. In both complexes, two [CuL] units coordinate to a nickel atom through the coordination of the phenoxido oxygen atoms forming triple phenoxido bridges between each Cu(II) and Ni(II). A couple of terminal dca or N-bonded thiocyanate ions complete the distorted octahedral geometry around Ni(II) in 1 and 2 respectively. Variable temperature magnetic susceptibility measurements show the presence of moderate antiferromagnetic exchange interactions mediated through the phenoxido bridges with J values (H = -J Sigma SiSi+1) of -49 and -42 cm(-1) for 1 and 2 respectively. (C) 2013 Elsevier Ltd. All rights reserved.

ASHUTOSH GHOSH

Chemistry

SAPTARSHI BISWAS

CARMEN DIAZ

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

&nbsp;

The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

&nbsp;

It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Polyhedron

Three new trinuclear hetero-metallic NiII2MII complexes with MII = Mn, Fe and Co have been synthesized using a [NiLR] “metalloligand”, where H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine. All complexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD and magnetic and electrochemical studies. In the three complexes, in addition to the double phenoxido bridges, the two terminal NiII atoms are linked to the central MII [M = Mn(1), Fe(2) and Co(3)] ion by means of a bridging carboxylato co-anion, giving rise to a linear NiII-MII-NiII structure. Variable temperature magnetic susceptibility measurements show the presence of weak ferromagnetic and antiferromagnetic exchange interactions mediated through the double phenoxido bridges with J values of +8.5 and −3.0 cm−1 for complexes 1 and 2, respectively. Compound 3 shows the presence of antiferromagnetic interactions. Cyclic voltammetry shows a common quasi-reversible one electron oxidation corresponding to the Ni(II)/Ni(III) process in 1–3 and an irreversible M(II)/M(III) oxidation for Mn(1) and Fe(2). © 2017

Inorganica Chimica Acta

Rare trinuclear NiII2MII complexes (MIIâ€¯=â€¯Mn, Fe and Co) with a reduced Schiff base ligand: Synthesis, structures and magnetic properties

A new trinuclear complex [(CuLα-Me)2Co(bnz)2] (1) has been synthesized by using a metalloligand [CuLα-Me] (H2Lα-Me = N,N′-bis(α-methylsalicylidene)-1,3-propanediamine, bnz = benzoate) with trans-coordinated syn-syn bridging benzoate group (1κO:2κO′). The syn-syn coordinative selectivity of carboxylate towards this trinuclear unit leads exclusively to the formation of linear coordination cluster. Such coordinative adaptability is exploited for supramolecular assembly using a dicarboxylate linker, terephthalate (tph, 1,4-benzenedicarboxylate) which yielded a tailored one-dimensional quasi-linear coordination polymer [(CuLα-Me)2Co(tph)]n·2nH2O (2) having the linear trinuclear node. Isothermal magnetization measurement at 2 K suggests that both 1 and 2 posses S = 1/2 ground spin state indicating the presence of antiferromagnetic coupling at low temperature. The variable-temperature magnetic susceptibility measurements also reveal that both compounds are antiferromagnetically coupled with exchange coupling constants (J) of -17.3 and -9.2 cm-1 for 1 and 2, respectively. The nature and magnitude of exchange interactions are further corroborated by density functional calculations. © 2015 Elsevier Ltd. All rights reserved.

An adaptable heterometallic trinuclear coordination cluster in the synthesis of tailored one-dimensional architecture: Structural characterization, magnetic analysis and theoretical calculations

Three new trinuclear heterometallic NiII-MnII complexes have been synthesized using a [NiL] metalloligand, where H 2L = N,N′-bis(salicylidene)-1,3-propanediamine. The complexes [(NiL)2Mn(OCnn)2(CH3OH)2] ·CH3OH (1), [(NiL)2Mn(OPh)2(CH 3OH)2][(NiL)2Mn(OPh)2]·H 2O (2), and [(NiL)2Mn(OSal)2(CH 3OH)2]·2[NiL] (3) (where OCnn = cinnamate, OPh = phenylacetate, OSal = salicylate) have been structurally characterized. In all three complexes, in addition to the double phenoxido bridge, the two terminal NiII atoms are linked to the central MnII by means of a syn-syn bridging carboxylate, giving rise to a linear structure. Complexes 1 and 2 with Ni-O-Mn angles of 97.24 and 96.43°, respectively, exhibit ferromagnetic interactions (JNi-Mn = +1.38 and +0.50 cm-1, respectively), whereas 3 is antiferromagnetic (JNi-Mn = -0.24 cm-1), having an Ni-O-Mn angle of 98.51°. DFT calculations indicate that there is a clear magneto-structural correlation between the Ni-O-Mn angle and JNi-Mn values, which is in agreement with the experimental results. © 2014 American Chemical Society.

Fulltext

Inorganic Chemistry

Ferro- to antiferromagnetic crossover angle in diphenoxido- and carboxylato-bridged trinuclear Ni II 2 -Mn II complexes: Experimental observations and theoretical rationalization

Three new nickel(II)-hmt complexes [Ni(2-nbz)2(μ2- hmt)(H2O)2]n (1), [Ni(3-nbz) 2(hmt)2(H2O)2]·2(3-nbzH) (2) and [Ni(4-nbz)2(μ2-hmt)(H2O) 2]n (3) bearing isomeric nitrobenzoates [2-nbz = 2-nitrobenzoate, 3-nbz = 3-nitrobenzoate, 4-nbz = 4-nitrobenzoate and hmt = hexamethylenetetramine] have been synthesised by self-assembly and crystallographically characterised. Compounds 1 and 3 are zigzag chain 1D polymers whereas complex 2 is a monomer. Various weak forces, i.e. -NO 2-π, π-π and CH-π interactions play a key role in stabilizing the structures of 1, 2 and 3, which are further extended into the distinct 1D (2), 2D (1) or 3D (3) H-bonded networks via the intermolecular O-H⋯N (1-3) and O-H⋯O (3) interactions involving the H 2O ligands and hexamethylenetetramine and/or nitrobenzoate moieties. The H-bonded 2D and 3D networks in 1 and 3 have been topologically classified as trinodal 3,4,6-connected or 3,4,4-connected nets with the 3,4,6L6 or sqc69 topologies, respectively. © 2014 Elsevier Ltd. All rights reserved.

Nickel(II) complexes self-assembled from hexamethylenetetramine and isomeric nitrobenzoates: Structural diversity and supramolecular features

A tetra-nuclear, star-shaped hetero-metallic copper(ii)-manganese(ii) complex, [{CuL(H 2 O)} 2 (CuL)Mn](ClO 4 ) 2 (1) has been synthesized by reacting the "complex as ligand" [CuL] with Mn(ClO 4 ) 2 where H 2 L is the tetradentate di-Schiff base derived from 1,3-propanediamine and 2-hydroxyacetophenone. Upon treatment with the polyatomic anions azide, cyanate, or thiocyanate in methanol medium, complex 1 transforms into the corresponding trinuclear species [(CuL) 2 Mn(N 3 ) 2 ] (2), [(CuL) 2 Mn(NCO) 2 ] (3) and [(CuL) 2 Mn(NCS) 2 ] (4). All four complexes have been structurally and magnetically characterized. In complex 1 the central Mn(ii) ion is encapsulated by three terminal [CuL] units through the formation of double phenoxido bridges between Mn(ii) and each Cu(ii). In complexes 2-4 one of the CuL units is replaced by a couple of terminal azide, N-bonded cyanate or N-bonded thiocyanate ions respectively and the central Mn(ii) ion is connected to two terminal Cu(ii) ions through a double asymmetric phenoxido bridge. Variable temperature magnetic susceptibility measurements show the presence of moderate ferrimagnetic exchange interactions in all the cases mediated through the double phenoxido bridges with J values (H = -JS i S i + 1 ) of -41.2, -39.8 and -12.6 cm -1 (or -40.5 and -12.7 cm -1 if we use a model with two different exchange coupling constants) for the tetranuclear MnCu 3 cluster in compound 1 and -20.0, -17.3 and -32.5 cm -1 for the symmetric trinuclear MnCu 2 compounds 2-4. These ferrimagnetic interactions lead to spin ground states of 1 (5/2 - 3*1/2) for compound 1 and 3/2 (5/2 - 2*1/2) for compounds 2-4. © 2012 The Royal Society of Chemistry.

Dalton Transactions

Synthesis of the first heterometalic star-shaped oxido-bridged MnCu 3 complex and its conversion into trinuclear species modulated by pseudohalides (N 3 - , NCS - and NCO - ): Structural analyses and magnetic properties

Three heterometallic copper(II)-mercury(II) complexes, [(CuL-CH 3)HgCl 2] (1), [(CuL-CH 3) 2HgCl 2] (2), and [(CuL-CH 2-HgCl) 2] (3), have been synthesized by reacting the "complex as ligand" [CuL-CH 3] with HgCl 2 by varying the reaction conditions and stoichiometry of the reactants, where H 2L-CH 3 = the di-Schiff base of 1,3-propanediamine and 2-hydroxyacetophenone. All three complexes have been characterized by X-ray single-crystal structure, elemental, and spectroscopic analyses. In complex 1, the Hg(II) ion is bonded by two phenoxido oxygen atoms of a [CuL-CH 3] moiety and two terminal chloride ions to form a dinuclear species. In the trinuclear complex 2, the central Hg(II) ion is coordinated by two terminal [CuL-CH 3] units through one phenoxido oxygen from each unit and two chloride ions. On the other hand, in the tetranuclear complex 3, the Hg(II) ion has a distorted-tetrahedral geometry, being bonded to one chloride, two phenoxido oxygen atoms of one [CuL-CH 2] unit, and a methyl carbon atom of another [CuL-CH 2] unit. The structure of complex 3 reveals an unprecedented heptadentate coordination mode (1-κ 4NN′OO′:2- κ 2OO′:3-κC) of the Schiff base ligand that resulted in a unique organomercury metallamacrocycle. © 2012 American Chemical Society.

Organometallics

Copper(II)-mercury(II) heterometallic complexes derived from a salen-type ligand: A new coordination mode of the old Schiff base ligand

One new complex of Cu(II), [(CuL)2Cu3(N 3)6]n (1) has been synthesized by reacting the "ligand complex", [CuL] with copper acetate and sodium azide (NaN 3) in methanol-water where the di-Schiff base ligand H2L = N,N′-bis(α-methylsalicylidene)-1,3-propanediamine. The X-ray single crystal structural analysis shows that complex 1 consists of an incomplete face-sharing double cube of four Cu(II) ions with the formula of [(CuL) 2Cu2(N3)2]2+ which are connected by [Cu(N3)4]2- unit to form a novel 1D chain. © 2012 Elsevier B.V. All rights reserved.

Journal of Molecular Structure

A novel 1D chain of azido bridged copper(II) with a salen-type di-Schiff base ligand

Two new polynuclear complexes of Cu(II), [(CuL 1 )Cu(N 3 C 2 ) 2 ] n (1) and [(CuL 2 ) 2 Cu(N 3 C 2 ) 2 ] ·H 2 O (2), have been synthesized by reacting the "ligand complexes", [CuL 1 ] and [CuL 2 ] respectively with copper perchlorate and sodium dicyanamide (NaN 3 C 2 ) in ethanol-water, where the di-Schiff base ligands H 2 L 1 = N,N′-bis(salicylidene)-1,3-propanediamine and H 2 L 2 = N,N′-bis(α-methylsalicylidene)-1,3-propanediamine. Structural analysis shows that complex 1 is a 2D polymer formed by linking the dinuclear units through a μ 1,5 -dicyanamido bridge. It contains alternating helical chains of P and M types. Complex 2 is a discrete bent trinuclear species where phenoxido groups of two terminal "ligand complexes" coordinate to a central Cu(II) along with terminally coordinated dicyanamido anions. Both complexes exhibit irreversible reductive Cu(II)/Cu(I) and quasi-reversible oxidative Cu(II)/Cu(III) responses in cyclic voltammetry. The electrochemically generated Cu(I) species for both complexes are unstable and undergo disproportionation to Cu 0 and Cu 2+ . © 2012 Elsevier Ltd. All rights reserved.

Structural variations in polynuclear copper(II) complexes based on salicylaldimine type ligands along with dicyanamido co-ligand

Two new trinuclear hetero-metallic copper(ii)-zinc(ii) complexes [(CuL)2Zn(N3)2] (1A and 1B) have been synthesized using [CuL] as a so-called "metalloligand" (where H 2L = N,N′-bis(salicylidene)-1,3-propanediamine) and structurally characterized. Complexes 1A and 1B have the same molecular formula but crystallize in different crystal systems (triclinic for 1A and monoclinic for 1B) with space group P1 for 1A and P21/c for 1B. 1A is an angular trinuclear species, in which two terminal four-coordinate square planar "metalloligand" [CuL] are coordinated to a central Zn(ii) through double phenoxido bridges. The Zn(ii) is in a six-coordinate distorted octahedral environment being bonded additionally to two mutually cis nitrogen atoms of terminal azide ions. In complex 1B, in addition to the double phenoxido bridge, the two terminal Cu(ii) ions are linked to the central Zn(ii) via a μ-l,l azido bridge giving rise to a square pyramidal environment around the Cu(ii) ions and consequently the structure becomes linear. These two species can be considered as "linear-bent" isomers. EPR spectra and ESI mass spectra show that the two isomers are identical in solution. The DFT calculation reveals that the energy of 1A is 7.06 kcal mol-1 higher than that of 1B. The existence of both isomers in the solid state suggests that crystal packing interactions in 1A are more efficient and probably compensate for the difference in energy. © 2012 The Royal Society of Chemistry.

An unprecedented "linear-bent" isomerism in tri-nuclear Cu 2IIZnII complexes with a salen type di-Schiff base ligand

The first triple phenoxido-bridged triangular (NiCu2II)-Cu-II complexes with a N2O2 donor di-Schiff base and pseudohalide (N(CN)(2)(-) or NCS-) ligands: Structural analyses and magnetic properties

Journal	Data powered by TypesetPolyhedron
Publisher	Data powered by TypesetPERGAMON-ELSEVIER SCIENCE LTD
ISSN	0277-5387
Open Access	No