Manganese(II), lead(II) and cadmium(II) coordination complexes containing a tetrazole‐based acylamide ligand: synthesis and the influence of the metal ions on the structures

Three new manganese(II), lead(II) and cadmium(II) coordination complexes have been prepared by reaction of N‐(1H‐tetrazol‐5‐yl)cinnamamide (HNTCA) with divalent metal salts (MnCl₂, PbCl₂ and CdCl₂) in a mixed‐solvent system, affording mononuclear to trinuclear structures namely, bis(methanol‐κO)bis[5‐(3‐phenylprop‐2‐enamido)‐1H‐1,2,3,4‐tetrazol‐1‐ido‐κ²N¹,O]manganese(II), [Mn(C₁₀H₈N₅O)₂(CH₃OH)₂], (1), bis[μ‐5‐(3‐phenylprop‐2‐enamido)‐1H‐1,2,3,4‐tetrazol‐1‐ido]‐κ³N¹,O:N²;κ³N²:N¹,O‐bis{aqua[5‐(3‐phenylprop‐2‐enamido)‐1H‐1,2,3,4‐tetrazol‐1‐ido‐κ²N¹,O]lead(II)}, [Pb₂(C₁₀H₈N₅O)₄(H₂O)₂], (2), and hexakis[μ₂‐5‐(3‐phenylprop‐2‐enamido)‐1H‐1,2,3,4‐tetrazol‐1‐ido‐κ³N¹,O:N²]tricadmium(II), [Cd₃(C₁₀H₈N₅O)₆], (3). The structures of these three compounds reveal that the nature of the metal ions and the side groups of the organic building blocks have a significant effect on the structures of the coordination compounds formed. Intermolecular hydrogen bonds link the molecules into two‐dimensional [complex (1)] and three‐dimensional hydrogen‐bonded networks. Complexes (2) and (3) show significant fluorescence, while complex (1) displays no fluorescence.     

Synthese und Charakterisierung von Aquapentachloroplatinaten(IV) – Struktur von [K(18-Krone-6)][PtCl5(H2O)]

Synthesis and Characterization of Aquapentachloroplatinates(IV) – Structure of [K(18-crown-6)][PtCl₅(H₂O)] The crown ether complex of the aquapentachloroplatinic acid of the composition [H₁₃O₆][PtCl₅(H₄O₂)] · 2(18-cr-6) ( 2 ) reacts with K₂CO₃ and [NⁿBu₄]OH in aqueous solution to give [K(18-cr-6)][PtCl₅(H₂O)] ( 5 a ) and [NⁿBu₄][PtCl₅(H₂O)] · ¹/₂ (18-cr-6) · H₂O ( 5 b ), respectively. Both compounds were characterized by microanalysis, vibrational (IR, Raman) and NMR (¹H, ¹³C, ¹⁹⁵Pt) spectroscopy. The X-ray structure analysis of 5 a (orthorhombic, pnma; a = 16,550(4), b = 18,044(3), c = 7,415(1) Å; Z = 4; R1 = 0,0183; wR2 = 0,0414) reveals that the crystal is threaded by chains built up of [PtCl₅(H₂O)]^? and [K(18-cr-6)]⁺ units. There are tight K …? Cl contacts (d(K? Cl1)) = 3,0881(9) Å and O_W? H? O_cr hydrogen bridges (d(O1 …? O2) = 2,806(3) Å) between these units. The coordination polyhedron [PtCl₅O] has approximately C_4v symmetry.     

trans‐Diaquabis(3‐hydroxybenzoato‐κO1)bis(nicotinamide‐κN1)copper(II)

The title compound, [Cu(C₇H₅O₃)₂(C₆H₆N₂O)₂(H₂O)₂], is a two‐dimensional hydrogen‐bonded supramolecular complex. The Cu^II ion resides on a centre of symmetry and is in an octahedral coordination environment comprising two pyridine N atoms, two carboxylate O atoms and two O atoms from water molecules. Intermolecular N—H...O and O—H...O hydrogen bonds produce R₂²(4), R₂²(8) and R₂²(15) rings which lead to one‐dimensional polymeric chains. An extensive two‐dimensional network of N—H...O and O—H...O hydrogen bonds and C—H...π interactions are responsible for crystal stabilization.     

A new copper(II) supramolecular coordination polymer and a dinuclear compound with multifunctional 2‐amino‐5‐sulfobenzoic acid and flexible N‐donor ligands: synthesis,structure and characterization

Multifunctional 2‐amino‐5‐sulfobenzoic acid (H₂afsb) can exhibit a variety of roles during the construction of supramolecular coordination polymers. The pendant carboxylic acid, sulfonic acid and amino groups could not only play a role in directing bonding but could also have the potential to act as hydrogen‐bond donors and acceptors, resulting in extended high‐dimensional supramolecular networks. Two new Cu^II coordination compounds, namely catena‐poly[[[diaquacopper(II)]‐μ‐1,6‐bis(1H‐1,2,4‐triazol‐1‐yl)hexane‐κ²N⁴:N^4′] bis(3‐amino‐4‐carboxybenzenesulfonate) dihydrate], {[Cu(C₁₀H₁₆N₆)₂(H₂O)₂](C₇H₆NO₅S)₂·2H₂O}_n or {[Cu(bth)₂(H₂O)₂](Hafsb)₂·2H₂O}_n, (1), and bis(μ‐2‐amino‐5‐sulfonatobenzoato‐κ²O¹:O^1′)bis{μ‐1,2‐bis[(1H‐imidazol‐1‐yl)methyl]benzene‐κ²N³:N^3′}bis[aquacopper(II)] trihydrate, [Cu₂(C₇H₅NO₅S)₂(C₁₄H₁₄N₄)₂(H₂O)₂]·3H₂O or [Cu₂(afsb)₂(obix)₂(H₂O)₂]·3H₂O, (2), have been obtained through the assembly between H₂afsb and the Cu^II ion in the presence of the flexible N‐donor ligands 1,6‐bis(1H‐1,2,4‐triazol‐1‐yl)hexane (bth) and 1,2‐bis[(1H‐1,2,4‐triazol‐1‐yl)methyl]benzene (obix), respectively. Compound (1) consists of a cationic coordination polymeric chain and 3‐amino‐4‐carboxybenzenesulfonate (Hafsb⁻) anions. Compound (2) exhibits an asymmetric dinuclear structure. There are hydrogen‐bonded networks within the lattices of (1) and (2). Interestingly, both (1) and (2) exhibit reversible dehydration–rehydration behaviour.     

[Cu(phen)2(μ‐IDA)Cu(phen)](ClO4)2·CH3OH: tridentate and monodentate binding to two copper(II) species by a bridging ligand

The stoichiometric reaction of 1,10‐phenanthroline (phen), imino­di­acetic acid (IDA‐H₂) and Cu(ClO₄)₂ in a H₂O–CH₃OH (2:1) solution yields μ‐imino­diacetato‐2:1κ⁴O,N,O′:O′′‐tris(1,10‐phenanthroline)‐1κ⁴N,N′;2κ²N,N′‐dicopper(II) diperchlorate methanol solvate, [Cu₂(C₄H₅NO₄)(C₁₂H₈N₂)₃](ClO₄)₂·CH₃OH. The IDA ligand bridges the two Cu^II ions via a carboxyl­ate group and uses one further N and an O atom of the second carboxylate group to complete a fac‐tridentate coordination at one Cu centre. A phen ligand completes a distorted square‐pyramidal coordination at this metal atom, although there is weak coordination by a perchlorate O atom at a sixth position. The second Cu centre has a distorted trigonal–bipyramidal coordination to two phen moieties and a carboxyl­ate O atom.     

A chloro(2‐pyridinecarboxaldehyde)(2,2′:6′,2′′‐ter­pyridine)­ruthenium(II) complex

The aldehyde moiety in the title complex, chloro(2‐pyridinecarboxaldehyde‐N,O)(2,2′:6′,2′′‐terpyridine‐κ³N)ruthenium(II)–chloro­(2‐pyridine­carboxyl­ic acid‐N,O)(2,2′:6′,2′′‐ter­pyridine‐κ³N)­ruthenium(II)–perchlorate–chloro­form–water (1.8/0.2/2/1/1), [RuCl­(C₆H₅NO)­(C₁₅H₁₁N₃)]_1.8[RuCl­(C₆H₅­NO₂)(C₁₅H₁₁N₃)]_0.2­(ClO₄)₂·­CHCl₃·­H₂O, is a structural model of substrate coordination to a transfer hydrogenation catalyst. The title complex features two independent Ru^II complex cations that display very similar distorted octahedral coordination provided by the three N atoms of the 2,2′:6′,2′′‐ter­pyridine ligand, the N and O atoms of the 2‐pyridine­carbox­aldehyde (pyCHO) ligand and a chloride ligand. One of the cation sites is disordered such that the aldehyde group is replaced by a 20 (1)% contribution from a carboxyl­ic acid group (aldehyde H replaced by carboxyl O—H). Notable dimensions in the non‐disordered complex cation are Ru—N 2.034 (2) Å and Ru—O 2.079 (2) Å to the pyCHO ligand and O—C 1.239 (4) Å for the pyCHO carbonyl group.     

Self-assembly of 1-D, 2-D,and 3-D transition-metal coordination polymers based on a T-shaped tripodal ligand 4-(4,5-dicarboxy-1H-imidazol-2-yl)pyridine 1-oxide

Three coordination polymers, {[Co(C₁₀H₅N₃O₅)(H₂O)₂]·H₂O}_n (1), {[Mn₃(C₁₀H₅N₃O₅)₂Cl₂(H₂O)₆]·2H₂O}_n (2), and {[Cu₃(C₁₀H₄N₃O₅)₂(H₂O)₃]·4H₂O}_n (3), based on a T-shaped tripodal ligand 4-(4,5-dicarboxy-1H-imidazol-2-yl)pyridine 1-oxide (H₃DCImPyO), were synthesized under hydrothermal conditions. The polymers showed diverse coordination modes, being characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray structure analysis. In 1, the HDCImPyO^2? generated a 1-D chain by adopting a μ₂-kN, O : kN′, O′ coordination mode to bridge two Co(II) ions in two bis-N,O-chelating modes. In 2, the HDCImPyO^2? adopted a μ₃-kN, O : kO′, O′′ : O′′′ coordination mode to bridge two crystallographically independent Mn(II) ions, forming a 2-D hcb network with {6³} topology. In 3, by adopting μ₄-kN, O : kO′, O′′ : kN′′, O′′′ : O′′′′ coordination, DCImPyO^3? bridged three crystallographically independent Cu(II) ions to form a 3-D framework having the stb topology.     

The synthesis,crystal structure and magnetic properties of a one‐dimensional terbium(III)–octacyanidomolybdate(V) assembly

A one‐dimensional cyanide‐bridged coordination polymer, poly[[aquadi‐μ‐cyanido‐κ⁴C:N‐hexacyanido‐κ⁶C‐(dimethylformamide‐κO)bis(3,4,7,8‐tetramethyl‐1,10‐phenanthroline‐κ²N,N′)terbium(III)molybdate(V)] 4.5‐hydrate], [MoTb(CN)₈(C₁₆H₁₆N₂)₂(C₃H₇NO)(H₂O)]·4.5H₂O}_n, has been prepared and characterized through IR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. The compound consists of one‐dimensional chains in which cationic [Tb(tmphen)₂(DMF)(H₂O)]³⁺ (tmphen is 3,4,7,8‐tetramethyl‐1,10‐phenanthroline) and anionic [Mo^V(CN)₈]³⁻ units are linked in an alternating fashion through bridging cyanide ligands. Neighbouring chains are connected by three types of hydrogen bonds (O—H...O, O—H...N and C—H...O) and by π–π interactions to form a three‐dimensional supramolecular structure. In addition, magnetic investigations show that ferromagnetic interactions exist in the compound.     

Diaquabis(4‐fluorobenzoato‐κO)bis(nicotinamide‐κN)cobalt(II)

The title compound, [Co(C₇H₄FO₂)₂(C₆H₆N₂O)₂(H₂O)₂], is a three‐dimensional hydrogen‐bonded supramolecular complex. The Co^II ion resides on a centre of symmetry and is in an octahedral coordination environment comprising two pyridyl N atoms, two carboxylate O atoms and two O atoms from water molecules. Intermolecular N—H...O and O—H...O hydrogen bonds produce R₃²(6), R₂²(12) and R₂²(16) rings, which lead to two‐dimensional chains. An extensive three‐dimensional network of C—H...F, N—H...O and O—H...O hydrogen bonds and π–π interactions are responsible for crystal stabilization.     

trans‐Diaquabis(nicotinamide‐κN)bis(salicylato‐κO)cobalt(II)

The title compound, [Co(C₇H₅O₃)₂(C₆H₆N₂O)₂(H₂O)₂], forms a three‐dimensional hydrogen‐bonded supramolecular structure. The Co^II ion is in an octahedral coordination environment comprising two pyridyl N atoms, two carboxylate O atoms and two O atoms from water molecules. Intermolecular N—H...O and O—H...O hydrogen bonds produce R₂²(8), R₂²(12) and R₂²(14) rings, which lead to two‐dimensional chains. An extensive three‐dimensional supramolecular network of C—H...O, N—H...O and O—H...O hydrogen bonds and C—H...π interactions is responsible for crystal structure stabilization. This study is an example of the construction of a supramolecular assembly based on hydrogen bonds in mixed‐ligand metal complexes.     

A coordinatively flexible hexadentate ligand gives structurally isomeric complexes M2(L)X3 (M = Cu,Zn; X = Br,Cl)

Polypyridyl multidentate ligands based on ethylenediamine backbones are important metal‐binding agents with applications in biomimetics and homogeneous catalysis. The seemingly hexadentate tpena ligand [systematic name: N,N,N′‐tris(pyridin‐2‐ylmethyl)ethylenediamine‐N′‐acetate] reacts with zinc chloride and zinc bromide to form trichlorido[μ‐N,N,N′‐tris(pyridin‐2‐ylmethyl)ethylenediamine‐N′‐acetato]dizinc(II), [Zn₂(C₂₂H₂₄N₅O₂)Cl₃], and tribromido[μ‐N,N,N′‐tris(pyridin‐2‐ylmethyl)ethylenediamine‐N′‐acetato]dizinc(II), [Zn₂Br₃(C₂₂H₂₄N₅O₂)]. One Zn^II ion shows the anticipated N₅O coordination in an irregular six‐coordinate site and is linked by an anti carboxylate bridge to a tetrahedral ZnX₃ (X = Cl or Br) unit. In contrast, the Cu^II ions in aquatribromido[μ‐N,N,N′‐tris(pyridin‐2‐ylmethyl)ethylenediamine‐N′‐acetato]dicopper(II)–tribromido[μ‐N,N,N′‐tris(pyridin‐2‐ylmethyl)ethylenediamine‐N′‐acetato]dicopper(II)–water (1/1/6.5) [Cu₂Br₃(C₂₂H₂₄N₅O₂)][Cu₂Br₃(C₂₂H₂₄N₅O₂)(H₂O)]·6.5H₂O, occupy two tpena‐chelated sites, one a trigonal bipyramidal N₃Cl₂ site and the other a square‐planar N₂OCl site. In all three cases, electrospray ionization mass spectra were dominated by a misleading ion assignable to [M(tpena)]⁺ (M = Zn²⁺ and Cu²⁺).     

Transition metal complexes with pyrazole‐derived ligands. XI. [Zn(μ‐L)(HL)(OAc)]2 (HL is 4‐acetyl‐3‐amino‐5‐methyl­pyrazole)

The title compound, bis(μ‐4‐acetyl‐3‐amino‐5‐methyl­pyrazol­ato‐N¹:N²)­bis­[(acetato‐O)­(4‐acetyl‐3‐amino‐5‐methyl­pyraz­ole‐N²)­zinc(II)], [Zn₂(C₆H₈N₃O)₂(C₂H₃O₂)₂(C₆H₉N₃O)₂], ex‐ists as a centrosymmetric binuclear mol­ecule with two tetrahedrally coordinated Zn atoms bridged by two pyrazolate anions. The geometry of the terminal and bridging pyrazole ligands are slightly different as a consequence of their differing modes of coordination.     

A novel cadmium(II) coordination polymer with a four‐connected (4,4)‐net based on a trinuclear cadmium(II) node

In the title cadmium(II) coordination polymer, poly[tri‐μ₄‐adipato‐bis(2‐phenyl‐1H‐1,3,7,8‐tetraazacyclopenta[l]phenanthrene‐κ²N⁷,N⁸)tricadmium(II)], [Cd₃(C₆H₈O₄)₃(C₁₉H₁₂N₄)₂]_n, one of the Cd atoms is in a distorted pentagonal bipyramidal coordination environment, surrounded by five O atoms from three adipate (adip) ligands and two N atoms from one 2‐phenyl‐1H‐1,3,7,8‐tetraazacyclopenta[l]phenanthrene (L) ligand. A second Cd atom occupies an inversion center and is coordinated by six O atoms from six adip ligands in a distorted octahedral geometry. The carboxylate ends of the adip ligands link Cd^II atoms to form unique trinuclear Cd^II clusters, which are further bridged by the adip linkers to produce a two‐dimensional layer structure. Topologically, each trinuclear Cd^II cluster is connected to four others through six adip ligands, thus resulting in a unique two‐dimensional four‐connected framework of (4,4)‐topology. This work may help the development of the coordination chemistry of 1,10‐phenanthroline derivatives.     

Three heterotrinuclear Schiff base complexes of nickel(II) with cobalt(II), copper(II) and manganese(II)

The title compounds, bis­(di­methyl­form­amide)‐1κO,3κO‐bis{μ‐2,2′‐[2,2′‐di­methyl­propane‐1,3‐diyl­bis­(nitrilo­methylidyne)]­diphenolato}‐1κ⁴N,N′,O,O′:2κ²O,O′;2κ²O,O′:3κ⁴N,N′,O,O′‐di‐μ‐nitrito‐1:2κ²N:O;2:3κ²O:N‐dinickel(II)­cobalt(II), [CoNi₂(NO₂)₂(C₁₉H₂₂N₂O₂)₂(C₃H₇NO)₂], (I), ‐copper(II), [CuNi₂(NO₂)₂(C₁₉H₂₂N₂O₂)₂(C₃H₇NO)₂], (II), and ‐manganese(II), [MnNi₂(NO₂)₂(C₁₉H₂₂N₂O₂)₂(C₃H₇NO)₂], (III), consist of centrosymmetric linear heterotrinuclear metal complexes. The three complexes are isostructural. There are three bridges across the Ni–M atom pairs (M is Co²⁺, Cu²⁺ or Mn²⁺) in each complex, involving two O atoms of a μ‐N,N′‐bis­(salicyl­idene)‐2,2′di­methyl‐1,3‐propane­diaminate ligand and an N—O moiety of a μ‐nitrito group. The coordination sphere around each metal atom, whether Co²⁺, Cu²⁺, Mn²⁺ or Ni²⁺, can be described as distorted octahedral. The Ni?M distances are 2.9988 (5) Å in (I), 2.9872 (5) Å in (II) and 3.0624 (8) Å in (III).     

Cobalt(II) and nickel(II) complexes of isoquinoline‐1‐carboxylate

trans‐Di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­cobalt(II) dihydrate, [Co(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, and trans‐di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­nickel(II) dihydrate, [Ni(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, contain the same isoquinoline ligand, with both metal atoms residing on a centre of symmetry and having the same distorted octahedral coordination. In the former complex, the Co—O(water) bond length in the axial direction is 2.167 (2) Å, which is longer than the Co—O(carboxylate) and Co—N bond lengths in the equatorial plane [2.055 (2) and 2.096 (2) Å, respectively]. In the latter complex, the corresponding bond lengths for Ni—O(water), Ni—O(carboxylate) and Ni—N are 2.127 (2), 2.036 (2) and 2.039 (3) Å, respectively. Both crystals are stabilized by similar stacking interactions of the ligand, and also by hydrogen bonds between the hydrate and coordinated water molecules.     

Synthesis,Structure, Photoluminescence,and Theoretical ­Calculation of an rtl‐type Zinc(II) Compound with Linear Trinuclear [Zn3(COO)4(μ2‐H2O)2] Subunits

The zinc(II) coordination polymer [Zn₃(BPT)₂(μ₂‐H₂O)₂(H₂O)₂]_n · n(DMA) ( 1 ) (H₃BPT = biphenyl‐3,4′,5‐tricarboxylic acid, DMA = N,N′‐dimethylactamide) was obtained by the solvothermal reaction of H₃BPT with Zn(NO₃)₂ in DMA/H₂O mixed solvent. Single crystal X‐ray analysis reveals that compound 1 has a complicated 3D framework containing linear trinuclear [Zn₃(COO)₄(μ₂‐H₂O)₂] clusters as building subunits, which can be simplified into a (3,6)‐connected rtl topological network with the Schläfli symbol {4.6²}₂{4².6¹⁰.8³}. The calculated results of total and partial density of states (DOS) indicate that the luminescence of 1 mainly originates from intraligand charge transfer.     

Synthesis,spectroscopic and X-ray crystallographic properties of manganese compounds of keto- and enol-coordinated di-2-pyridyl ketone benzoyl hydrazone (dpkbh). Reactions of [Mn(CO)5Br] with dpkbh

Reactions between [Mn(CO)₅Br] and dpkbh in low boiling solvents in air gave fac-[Mn^I(CO)₃(κ²-N_py,N_im-dpkbh)Br]·H₂O, [Mn^IIBr₂(κ³-N_py,N_im,O-dpkbh)], and [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂]·0.5H₂O (N_im = imine nitrogen and N_py = pyridyl nitrogen). Crystallization of fac-[Mn^I(CO)₃(κ²-N_py,N_im-dpkbh)Br]·H₂O from dmso or CH₃CN produced dark red crystals of [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂]·nX (X = dmso, n = 1 and X = H₂O, n = 0.22). This is in contrast to the reaction of [Re(CO)₅Cl] with dpkbh in refluxing toluene to form fac-[Re^I(CO)₃(κ²-,N_py,N_py-dpkbh)Cl] which can be crystallized from CH₃CN, dmso or dmf to form fac-[Re^I(CO)₃(κ²-,N_py,N_py-dpkbh)Cl]·nX (X = CH₃CN, n = 0 and solvate = dmso or dmf, n = 1). Infrared spectral measurements are consistent with keto coordination of dpkbh to Mn(I) in fac-[Mn^I(CO)₃(κ²-N_py,N_im-dpkbh)Br]·H₂O and Mn(II) in [Mn^IIBr₂(κ³-N_py,N_im,O-dpkbh)] plus enol coordination of the amide-deprotonated dpkbh, to the Mn(II) center in [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂]·0.5H₂O. Electronic absorption spectral measurements in non-aqueous solvents indicate sensitivity of fac-[Mn^I(CO)₃(κ²-N_py,N_im-dpkbh)Br]·H₂O and [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂]·0.5H₂O to changes in their outer-shell environments. X-ray crystallographic analyses elucidated the identities of [Mn^IIBr₂(κ³-N_py,N_im,O-dpkbh)] and [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂]·nX and divulged weaker coordination of [dpkbh] to Mn(II) in [Mn^IIBr₂(κ³-N_py,N_im,O-dpkbh)] and stronger coordination of [dpkbh-H]^? to Mn(II) in [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂]·0.22H₂O. Low-temperature X-ray structural analyses were employed to account for the disorder in the structure of [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂] and the short NH bond distance observed in the structure of [Mn^IIBr₂(κ³-N_py,N_im,O-dpkbh)]. A PLATON Squeeze treatment was invoked to account for the fractional occupancy of lattice water in the structure of [Mn^II(κ³-N_py,N_im,O-dpkbh-H)₂].     

Ligand‐forced dimerization of copper(I)–olefin complexes bearing a 1,3,4‐thiadiazole core

As an important class of heterocyclic compounds, 1,3,4‐thiadiazoles have a broad range of potential applications in medicine, agriculture and materials chemistry, and were found to be excellent precursors for the crystal engineering of organometallic materials. The coordinating behaviour of allyl derivatives of 1,3,4‐thiadiazoles with respect to transition metal ions has been little studied. Five new crystalline copper(I) π‐complexes have been obtained by means of an alternating current electrochemical technique and have been characterized by single‐crystal X‐ray diffraction and IR spectroscopy. The compounds are bis[μ‐5‐methyl‐N‐(prop‐2‐en‐1‐yl)‐1,3,4‐thiadiazol‐2‐amine]bis[nitratocopper(I)], [Cu₂(NO₃)₂(C₆H₉N₃S)₂], (1), bis[μ‐5‐methyl‐N‐(prop‐2‐en‐1‐yl)‐1,3,4‐thiadiazol‐2‐amine]bis[(tetrafluoroborato)copper(I)], [Cu₂(BF₄)₂(C₆H₉N₃S)₂], (2), μ‐aqua‐bis{μ‐5‐[(prop‐2‐en‐1‐yl)sulfanyl]‐1,3,4‐thiadiazol‐2‐amine}bis[nitratocopper(I)], [Cu₂(NO₃)₂(C₅H₇N₃S₂)₂(H₂O)], (3), μ‐aqua‐(hexafluorosilicato)bis{μ‐5‐[(prop‐2‐en‐1‐yl)sulfanyl]‐1,3,4‐thiadiazol‐2‐amine}dicopper(I)–acetonitrile–water (2/1/4), [Cu₂(SiF₆)(C₅H₇N₃S₂)₂(H₂O)]·0.5CH₃CN·2H₂O, (4), and μ‐benzenesulfonato‐bis{μ‐5‐[(prop‐2‐en‐1‐yl)sulfanyl]‐1,3,4‐thiadiazol‐2‐amine}dicopper(I) benzenesulfonate–methanol–water (1/1/1), [Cu₂(C₆H₅O₃S)(C₅H₇N₃S₂)₂](C₆H₅O₃S)·CH₃OH·H₂O, (5). The structure of the ligand 5‐methyl‐N‐(prop‐2‐en‐1‐yl)‐1,3,4‐thiadiazol‐2‐amine (Mepeta ), C₆H₉N₃S, was also structurally characterized. Both Mepeta and 5‐[(prop‐2‐en‐1‐yl)sulfanyl]‐1,3,4‐thiadiazol‐2‐amine (Pesta ) (denoted L ) reveal a strong tendency to form dimeric {Cu₂L ₂}²⁺ fragments, being attached to the metal atom in a chelating–bridging mode via two thiadiazole N atoms and an allylic C=C bond. Flexibility of the {Cu₂(Pesta )₂}²⁺ unit allows the Cu^I atom site to be split into two positions with different metal‐coordination environments, thus enabling the competitive participation of different molecules in bonding to the metal centre. The Pesta ligand in (4) allows the Cu^I atom to vary between water O‐atom and hexafluorosilicate F‐atom coordination, resulting in the rare case of a direct Cu^I…FSiF₅²⁻ interaction. Extensive three‐dimensional hydrogen‐bonding patterns are formed in the reported crystal structures. Complex (5) should be considered as the first known example of a Cu^I(C₆H₅SO₃) coordination compound. To determine the hydrogen‐bond interactions in the structures of (1) and (2), a Hirshfeld surface analysis has been performed.     

First‐row transition metal–pyridine (py)–sulfate [(py)xM](SO4) complexes (M = Ni,Cu and Zn): crystal field theory in action

The crystal structures of three first‐row transition metal–pyridine–sulfate complexes, namely catena‐poly[[tetrakis(pyridine‐κN)nickel(II)]‐μ‐sulfato‐κ²O:O′], [Ni(SO₄)(C₅H₅N)₄]_n, (1), di‐μ‐sulfato‐κ⁴O:O‐bis[tris(pyridine‐κN)copper(II)], [Cu₂(SO₄)₂(C₅H₅N)₆], (2), and catena‐poly[[tetrakis(pyridine‐κN)zinc(II)]‐μ‐sulfato‐κ²O:O′‐[bis(pyridine‐κN)zinc(II)]‐μ‐sulfato‐κ²O:O′], [Zn₂(SO₄)₂(C₅H₅N)₆]_n, (3), are reported. Ni compound (1) displays a polymeric crystal structure, with infinite chains of Ni^II atoms adopting an octahedral N₄O₂ coordination environment that involves four pyridine ligands and two bridging sulfate ligands. Cu compound (2) features a dimeric molecular structure, with the Cu^II atoms possessing square‐pyramidal N₃O₂ coordination environments that contain three pyridine ligands and two bridging sulfate ligands. Zn compound (3) exhibits a polymeric crystal structure of infinite chains, with two alternating zinc coordination environments, i.e. octahedral N₄O₂ coordination involving four pyridine ligands and two bridging sulfate ligands, and tetrahedral N₂O₂ coordination containing two pyridine ligands and two bridging sulfate ligands. The observed coordination environments are consistent with those predicted by crystal field theory.     

trans-Bis(azido-κN)bis(pyridine-2-carboxamide-κ2N1,O2)nickel(II)

In the title compound, [Ni(N₃)₂(C₆H₆N₂O)₂], the Ni^II atom lies on an inversion centre. The distorted octahedral nickel(II) coordination environment contains two planar trans-related N,O-chelating picolinamide ligands in one plane and two monodentate azide ligands perpendicular to this plane. Molecules are linked into a three-dimensional framework by N—H...N hydrogen bonds.