A survey of the fascinating structural chemistry of the zinc-triad 1,1-dithiolates is presented. A total of twelve distinct structural motifs are delineated ranging from monomeric, dimeric, tetrameric, linear polymeric, layer to 3-dimensional network architectures. Such diversity arises from the prevalent secondary bonding interactions, i.e. A⋯S, operating in the solid state. While the variation in structure suggests that the control of secondary interactions is difficult, a possible design tool for crystal engineering is identified, namely by moderating the steric profile of thiolate-bound organic substituents, at least for the systems described herein.

Molecular architecture and supramolecular association in the zinc-triad 1,1-dithiolates. Steric control as a design element in crystal engineering?

The chemical reactions of a family of tetradentate pyridyl/imine ligands, L1, L2, and L3 (L1 = [N,N′-bis(2-pyridinylmethylene)]ethane-1,2-diamine; L2 = [N,N′-bis(pyridin-2-yl)benzylidene]ethane-1,2-diamine; L3 = [N,N′-bis(2-pyridinylmethylene)]propane-1,3-diamine), with NiII in the presence of various pseudohalides (N3−, SCN−, and NCO−) have served to prepare six different complexes, [Ni2(L1)2(N3)2](ClO4)2·H2O (1), [Ni2(L2)2(N3)2](ClO4)2 (2), [Ni2(L2)2(NCS)4] (3), [Ni2(L2)2(NCO)2](ClO4)2 (4), [Ni2(L3)2(NCO)2](ClO4)2 (5), and [Ni(L3)(N3)2] (6), which have been characterized by X-ray crystallography. Interestingly, four of these complexes are dinuclear and exhibit end-on (EO) pseudohalide bridges (1, 2, 4, and 5), one is dinuclear and bridged exclusively by the tetradentate ligand (3), and one is mononuclear (6). The bulk magnetization of the complexes bridged by EO pseudohalides has been studied, revealing these ligands to mediate ferromagnetic coupling between the NiII ions, with modeled coupling constant...

A versatile series of nickel(II) complexes derived from tetradentate imine/pyridyl ligands and various pseudohalides: azide and cyanate compared.

Three new dinuclear NiII complexes, [Ni2L2(NO3)2] (1), [Ni2L2(NO2)2] (2), and [Ni2L2(CH3COO)2(H2O)] (3), have been synthesized by using a tridentate Schiff base ligand, 2-({[3-(dimethylamino)propyl]imino}methyl)phenol (HL), along with a nitrate, nitrite, or acetate ion, respectively, as co-ligand. These three complexes were characterized by spectral analysis, X-ray crystallography, and variable-temperature magnetic susceptibility measurements. The structural analyses revealed that the NiII ions are coordinated by the deprotonated chelating tridentate Schiff base and possess a distorted octahedral geometry in all three complexes. Complexes 1 and 2 are two di-μ2-phenoxido-bridged species in which the nitrate and nitrite act as chelating co-ligands. However, in complex 3, in which the acetate anion is monodentate, an additional water bridge is present along with two μ2-phenoxido bridges making the complex a face-sharing bi-octahedron. Magnetic susceptibility measurements indicate an antiferromagnetic intradimer interaction in complexes 1 and 2 with J values of –20.34(5) and –25.25(4) cm–1, respectively, whereas complex 3 shows a dominant ferromagnetic exchange coupling with J = 19.11(9) cm–1. DFT calculations were performed, and the theoretically obtained J values of –19.99 (for 1), –24.19 (for 2) and 18.81 cm–1 (for 3) corroborate very well the experimental results. An attempt has also been made to correlate the effect of Ni···Ni distances and bridging Ni–O–Ni angles on the coupling constants of the NiII complexes through DFT calculations. The relative energy calculations show that the diphenoxido-bridged complexes are stable at larger bridging angles, and consequently the coupling is antiferromagnetic, whereas with an additional water bridge, the formation of complexes with the Ni–O–Ni bridging angle in the ferromagnetic region is energetically profitable.

One Ferromagnetic and Two Antiferromagnetic Dinuclear Nickel(II) Complexes Derived from a Tridentate N,N,O‐Donor Schiff Base Ligand: A Density Functional Study of Magnetic Coupling

Mononuclear, dinuclear and polymeric 1D thiocyanato- and dicyanamido–copper(II) complexes based on tridentate coligands

Reaction of a 1 : 1 : 1 molar ratio of NiCl(2), NaN(3) and H(2)L, a tetradentate ligand N-(2-pyridyl)methyl)-N,N-bis(2'-hydroxy-3',5'-dimethylbenzyl)amine in methanol in presence of Et(3)N results in a turquoise precipitate, which affords deep green crystals of [Ni(2)(HL)(2)(N(3))(2)]*1.5CH(2)Cl(2) (1) and [Ni(2)(HL)(2)(N(3))(2)]*H(2)O (2) upon crystallization from CH(2)Cl(2)-MeOH or THF-MeOH, respectively. Both complexes reveal distorted octahedral NiN(4)O(2) coordination environments around the Ni(ii) centers with bis(micro-1,1-azido) bridging ligands. Complex 1 displays an unprecedented small Ni-N-Ni bridge angle of 90.4 degrees , whereas 2 contains the said angle of av. 98.7 degrees lying in the usual range observed for other comparable structures. The variable-temperature magnetic susceptibility together with the variable-field, variable-temperature (VTVH) magnetization measurements discern different ground states of S(t) = 0 for 1 and S(t) = 2 for 2. The magnetic behaviours of these compounds are discussed in the context of the known bis(end-on azido) bridging dinickel(II) complexes.

Ferromagnetic vs. antiferromagnetic coupling in bis(mu2-1,1-azido)dinickel(II) complexes with syn- and anti-conformations of the end-on azide bridges

A family of tetradentate ligands, [N,N′-bis(pyridine-2-yl)]ethane-1,2-diamine (L1), [N,N′-bis(pyridine-2-yl)]propane-1,3-diamine (L2) and [N,N′-bis(pyridine-2-yl)]butane-1,4-diamine (L3) has been prepared. These ligands differ only in the number of CH2 groups separating two pyridyl/imine moieties, however, in reactions with MnII and N−3 salts, they produce structurally very diverse solids; [Mn2(L1)3(N3)]n(ClO4)3n (1), [Mn2(L2)2(N3)2](PF6)2 (2) and [Mn2(L3)(N3)2]n(ClO4)2n (3). Complexes 1, 2 and 3 consist of azido-bridged magnetically dilute Mn2 pairs, arranged as 1-D, discrete and 2-D arrays, respectively. In these materials, the connection between Mn centers within the dinuclear entities occurs through mono-1,3-N−3, bis-1,3-N−3 and bis-1,1-N−3 bridges, respectively, for 1, 2 and 3. Bulk magnetic measurements reveal that the coupling within such units is antiferromagnetic (J = −1.8 cm−1, 1; J = −4.8 cm−1, 2) and ferromagnetic (J = +1.45 cm−1, 3), depending on whether the N−3 binding mode is end-to-end (EE) or end-on (EO). The reported values are given according to the convention H = −2JS1S2 for the spin-Hamiltonian.

Unexpected diversity and novel features within a family of new azide-bridged MnII complexes of pyridyl/imine ligands

Synthesis, crystal structure and magnetic properties of a mononuclear and a ferromagnetically coupled dinuclear nickel(II) complex derived from a hexadentate Schiff base ligand

The Zn atom in the centrosymmetric title compound, [Zn2(C8H8NS2)4], is almost symmetrically coordinated by one terminal bidentate N-phenyl-N-methyl­di­thio­carbamate ligand [Zn—S 2.348 (1) and 2.459 (1) A] and non-symmetrically coordinated by a second bidentate bridging di­thio­carbamate ligand [Zn—S 2.316 (1) and 2.980 (1) A]. The latter also uses its bridging S atom to coordinate the second Zn atom [Zn—S 2.378 (1) A], thus forming a dimeric binuclear complex. Taking into account the long Zn⋯S distance, the Zn atom has a distorted trigonal–bipyramidal coordination.

Bis(μ-N-methyl-N-phenyl­di­thio­carbamato)[bis(N-methyl-N-phenyl­di­thio­carbamato)­zinc(II)]

The Bi atom in the title compound, [Bi(C7H14NS2)3], is coordinated by six S atoms from three bidentate N-butyl-N-ethyl­di­thio­carbamate ligands; it is also engaged in an additional Bi⋯S interaction which links two tris(N-butyl-N-ethyl­di­thio­carbamato)­bismuth fragments into centrosymmetric binuclear dimers Thus, each of the Bi atoms in the dimer has a distorted pentagonal–bipyramidal environment, with one short axial Bi—S distance of 2608 (2) A, one long axial Bi⋯S interaction of 3334 (2) A, and five `regular' equatorial bonds in the range 2819 (2)-2867 (2) A

A. Usman

Papers

Unexpected diversity and novel features within a family of new azide-bridged MnII complexes of pyridyl/imine ligands

Synthesis, crystal structure and magnetic properties of a mononuclear and a ferromagnetically coupled dinuclear nickel(II) complex derived from a hexadentate Schiff base ligand

Bis(μ-N-methyl-N-phenyldithiocarbamato)[bis(N-methyl-N-phenyldithiocarbamato)zinc(II)]

Tris(N-butyl-N-ethyldithiocarbamato)bismuth(III)

A. Usman

Papers

Unexpected diversity and novel features within a family of new azide-bridged MnII complexes of pyridyl/imine ligands

Synthesis, crystal structure and magnetic properties of a mononuclear and a ferromagnetically coupled dinuclear nickel(II) complex derived from a hexadentate Schiff base ligand

Bis(μ-N-methyl-N-phenyl­di­thio­carbamato)[bis(N-methyl-N-phenyl­di­thio­carbamato)­zinc(II)]

Tris(N-butyl-N-ethyl­di­thio­carbamato)­bismuth(III)

Bis(μ-N-methyl-N-phenyldithiocarbamato)[bis(N-methyl-N-phenyldithiocarbamato)zinc(II)]

Tris(N-butyl-N-ethyldithiocarbamato)bismuth(III)