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The synthesis and structural characterization of two new complexes catena -[Ni(3-O-py)(3-HO-py) 2 (μ 1,3 -N 3 )(H 2 O)] ( 1 ) and catena -[Zn(μ-3-O-py)(μ 1,1 -N 3 )] ( 2 ), where 3-HO-py = 3-hydroxypyridine, are reported. The complexes were characterized by the elemental microanalyses, IR, and X-ray crystallography and by UV–Vis spectroscopy for complex 1 . Single crystal X-ray crystallography revealed the polymeric nature of the complexes: 1 as 1D with a single EE azide bridging, and 2 as 2D with μ(O,O′,N) bridging of the deprotonated 3-O-py anions and di-EO azide groups, respectively. In 1 the neutral and deprotonated 3-hydroxypyridine molecules act only as N-terminal ligands. The emission spectral properties of the Zn(II) complex were investigated.

The synthesis and structural characterization of two new polymeric zinc(II) azido complexes with pyridine- N -oxide derivative co-ligands, namely catena- [Zn(4-methylpyridine- N -oxide)(μ 1,1 –N 3 ) 2 ] ( 1 ) and catena- {[Zn 2 (μ 2 -isonicotinato- N -oxide) 2 (μ 1,1 –N 3 ) 2 (H 2 O) 3 ](H 2 O)} ( 2 ) are reported. Single crystal structure determination revealed the penta-coordinated geometry of the Zn(II) centers in the polymeric chains of 1 with di-EO azido bridging mode, whereas five and six coordination modes around Zn(II) centers are observed in complex 2 , and the 1D system is formed via alternating single EO-azide and μ(O,O′)-bridging carboxylate group of the isonicotinato- N -oxide molecules. The solid state luminescence properties of 1 were examined.

The interaction of 4-aminoantipyrine (aap) with metal(II) pseudohalides [M = Zn and Mn] in aqueous media resulted in three new complexes; [Zn(aap)(N3)2(H2O)]n (1), [Zn(aap)3][Zn(NCS)4]·1/2H2O (2), and [Mn(aap)2(NCS)2] (3). The structure of 1 reveals μ1,3-bridging azido groups connecting zinc centers to form 1D chains of polyhedra oriented along the c-axis of the monoclinic unit cell. The zinc(II) center is octahedrally coordinated by O(1) and N(1) of bidentate N,O chelating aap molecule, by N(11) and N(13) of μ1,3-bridging azido group, N(21) of a terminal azido group, and O(2) of aqua ligand, resulting in a ZnN4O2 geometry. The structure of complex 2 consists of [Zn(aap)3]2+ complex cations, [Zn(NCS)4]2− complex anions and disordered lattice water molecules. The structure of 3 reveals mononuclear complexes, where the Mn(II) centers are ligated by the exocyclic N and O donor atoms of two chelating aap molecules and two N atoms of terminal isothiocyanato ligands. Thermal properties and IR spectra of the complexes were investigated and shown to be consistent with the structures.

Three mononuclear thiocyanato-Cu(II) complexes have been synthesized: the mono-thiocyanato [Cu(cyclen-tpam)(NCS)]ClO4·3H2O (1) and [Cu(DPA)(NCS)ClO4] (2), and the dithiocyanato complex Cu(bdmpzpy)(NCS)2 (3), where cyclen-tpam = 1,4,7,10-tetrakis(propionamide)-1,4,7,10-tetraazacyclododecane, DPA = bis(2-pyridylmethyl)amine, and bdmpzpy = 2,6-bis[(2,5-dimethyl-1-pyrazolyl)methyl]pyridine. The single crystal X-ray crystallography of the complexes confirmed the perfect square pyramidal geometry (SP) in 1 and distorted SP geometry in 2 and 3 with N-bonding coordination mode for the thiocyanato ligands. The IR spectra of the complexes which were consistent with the N-bonding coordination mode of the thiocyanate group(s) and the visible spectra which revealed the square pyramidal geometry around the central Cu2+ ion were in complete agreement with the X-ray structural determination.

The interaction of 1,4-bis[bis(2-pyridylmethyl)aminomethyl]benzene ( p -Xy DPA ) with CuCl 2 ·2H 2 O has resulted in the isolation of the dinuclear compound [Cu 2 ( p -Xy DPA )Cl 4 ]·H 2 O ( 1 ). When the reaction was performed in presence of sodium perchlorate, sodium azide, sodium dicyanamide (Nadca) and disodium squarate (Na 2 C 4 O 4 ) the compounds [Cu 2 ( p -Xy DPA )(ClO 4 ) 2 Cl 2 ] ( 2 ), [Cu 2 ( p -Xy DPA )(N 3 ) 4 ]·2H 2 O ( 3 ), [Cu 2 ( p -Xy DPA )(dca) 4 ]·4H 2 O ( 4 ), and [Cu 2 ( p -Xy DPA )Cl 2 (H 2 O) 2 ](C 4 O 4 )·5.4H 2 O ( 5 ) were obtained, respectively. The complexes were characterized by IR and UV–vis. spectroscopy. The visible spectra of the complexes revealed the square pyramidal geometry around the central Cu 2+ ions. The molecular structures of the complexes 2 , 3 , 4 and 5 were determined by single crystal X-ray crystallography. This study revealed the dinuclear nature of the complexes and showed that the Cu(II) centers have distorted five-coordinate square pyramidal geometry with N 3 -donor atoms of the dipicolyl amine arms and the remaining coordination positions are occupied by the chloro and perchlorato ligands in 2 , the monodentate azido ligands in 3 or the monodentate terminal nitrile dca in 4 and by the chloro and aqua ligands in 5 with the squarate dianion as counter ion.

Two new manganese(II) azido complexes [Mn(L) 2 (N 3 ) 2 ] n with L = 2-aminopyridine ( 1 ) and 4-azidopyridine ( 2 ) have been synthesized and structurally characterized by spectroscopic and crystallographic methods. Both complexes 1 and 2 crystallize in the triclinic system, space group P-1, and their structures are featuring six-coordinate manganese centres, chains of [Mn(N 3 ) 2 ] n , and two trans 2-aminopyridine or 4-azidopyridine ligands giving 1D systems. In the [Mn(N 3 ) 2 ] n -chains of 1 each manganese atom is connected by double di end-on (EO) azido bridges forming cyclic Mn 2 N 2 units, whereas in 2 , the metal centers are alternatively bridged by double di-end-to-end (EE) and double di end-on (EO) azido ligands. The intra-chain Mn…Mn distances are 3.5350(12) in 1 , and 3.3701(18) and 5.032(3) A, in 2 , respectively. In 1 the polymeric chains of polyhedra are connected by hydrogen bonds of type N–H…N to generate a 2D supramolecular network. Magnetic susceptibility measurements were performed only for complex 1 which shows weak ferromagnetic interactions with a J value of 1.2 cm −1 .

The binucleating ligand, 1,1,2,2-tetrakis(carboxamido-2-methylpyridyl)ethane (H4Lpy) was prepared. In neutral aqueous medium the H4Lpy binds two metal(II) ions and the dinuclear complexes [Cu2(Lpy)(H2O)2]·10H2O (1) and [Pd2(Lpy)]·4H2O (2) are formed. The complexes were structurally characterized by X-ray crystallography. The two complexes crystallize in the triclinic system with space group P 1 ¯ . 1: a = 8.829(2), b = 9.080(2), and c = 12.414(3) A; α = 76.50(3), β = 79.12(3), and γ = 87.25(3)°; V = 950.3(4) A3 and Z = 1 and 2: a = 8.638(2), b = 10.009(2), and c = 10.448(2) A; α = 78.03(3), β = 69.66(3), and γ = 71.20(3)°; V = 797.2(3) A3 and Z = 1. The coordination polyhedron in 1 may be described as axially elongated square pyramid where the Cu(II) centers are coordinated with the four N atoms of the Lpy tetraanion and an O(3) atom of the aqua ligand. In complex 2, each Pd(II) center displays a distorted square planar geometry achieved by the four N-donor atoms of Lpy. The intra-dimeric M(1)⋯M(1A) distances in 1 and 2 are 6.9680(17) and 6.7345(18) A, respectively. Molecular mechanics (MM) calculations were applied on the two complexes to determine their molecular structures in the solid state. Fair agreement was obtained between the structures predicted by MM calculations (M⋯M distances are 6.574 and 5.890 Ǻ for 1 and 2, respectively) and X-ray crystal structures.

The three dicopper(II) complexes [Cu 2 (L endm )(ClO 4 ) 2 (H 2 O) 2 ](ClO 4 ) 2 ·2H 2 O ( 1 ), [Cu 2 (L endm )(N 3 ) 2 (H 2 O) 2 ](ClO 4 ) 2 ( 2 ), and [Cu 2 (L endm )(C 4 O 4 ) 2 (H 2 O) 2 ]·6H 2 O ( 3 ) (C 4 O 4 2− = 3,4-dihydroxycyclobut-3-en-1,2-dionate) were synthesized from the novel binucleating ligand 1,6-diazecine, L endm namely bis{[c,h](2-methylimidazolyl)}-1,6-diazecine-1,6-bis( N , N -dimethylamino-eth-2-yl). The perchlorato, 1 and the squarato complex 3 were structurally characterized by X-ray crystallography. The spectral and structural characterization, and electrochemical properties as well as thermogravimetric analyses of the complexes are reported. The Cu(II) centers in 1 and 3 displayed a distorted square pyramidal environment with the CuN 3 O 2 chromophore. In which the basal sites are occupied by the three nitrogen donors of L endm : N(1) of the N , N -dimethylamino-eth-2-yl side chain, N(2) of the 10-membered central 1,6-diazecine ring and N(3) of the non-protonated N atom of the imidazolyl, an O(1) of the aqua ligand in 1 or O(1) of the terminal squarato ligand in 3 , and an aqua ligand occupying the apical position. In both cases the L endm behaves as bis-tridentate bridging ligand with the intradinuclear Cu⋯Cu distances are in the range 7.38–7.51 A. The UV–Vis and IR spectroscopy, elemental and the thermal analyses of the complexes are in complete agreement with the assigned structural formulas. The cyclic voltametric properties of the two complexes 1 and 2 were also studied.

A new series of dinuclear oxalato-bridged copper(II) and nickel(II) complexes derived from tridentate amines: [Cu2(Medpt)2(μ-C2O4)](ClO4)2 (1), [Cu2(pmedien)2(μ-C2O4)](ClO4)2 (2), [Cu2(DPA)2(μ-C2O4)(ClO4)2]·2H2O (3), and [Ni2(Et2dien)2(μ-C2O4)(H2O)2](ClO4)2·2H2O (4) (C2O42− = oxalate dianion, Medpt = 3,3′-diamino-N-methyldipropylmine, pmedien = N,N,N′,N′′,N′′-pentamethyldiethylenetriamine, DPA = di(2-pyridylmethyl)amine and Et2dien = N,N-diethyldiethylenetriamine) were synthesized and structurally characterized by X-ray crystallography. The spectral and structural characterizations of these complexes are reported. In this series, structures consist of the C2O42− bridging the two M(II) centers in a bis-bidentate bonding mode. The Cu2+ centers are coordinated to the tridentate amines Medpt or pmedien in distorted SP geometry in 1 and 2, respectively, with the ClO4− groups as counter ions. In the other two complexes, distorted octahedral geometries were achieved by the three nitrogen donors of the DPA and by an oxygen atom from coordinated perchlorate ion in 3 and by the Et2dien and one water molecule in 4.

A novel series of pseudohalide- ( N 3 - NCS−) and perchlorato–Cu(II) complexes possessing a series of ligands with pyridyl-containing donors have been investigated. These include [Cu(pmap)ClO4)]ClO4 (1), [Cu(pmap)(N3)]ClO4 (2), [Cu(pmea)(N3)]ClO4·H2O (3), [Cu(dp-pa)(N3)]ClO4·½H2O (4), [Cu(pzdepy)ClO4]ClO4 (5), [Cu(pzdepy)(NCS)]ClO4 (6) and [Cu2(L)(NCS)4]·2CH3CN (7) where pmap = bis[2-(2-pyridylethyl)]-(2-pyridylmethyl)amine, pmea = bis(2-pyridylmethyl)-2-(2-pyridylethyl)amine, dp-pa = N-propanamide-N,N-bis(2-pyridylmethyl)amine, pzdepy = N,N′-bis[2-(2-pyridylethyl)]piperazine and L = 3,5-bis[bis(2-pyridylmethyl)aminomethyl]-toluene. All complexes were characterized by elemental analyses, IR and UV–Visible spectroscopy. The visible spectra of all complexes reveal the square-pyramidal geometries (SP) around the central Cu2+ ion. IR spectra confirmed the coordination of the ClO 4 - group in 1 and 5 and the N-donor thiocyanate group in complexes 6 and 7. The X-ray structure determination of the pseudohalide complexes 2, 6 and 7 confirmed the monodentate coordination nature of N 3 - and NCS− ions. The structure of 2 or 6 consists of isolated [Cu(pmap)(N3)]+ or [Cu(pzdepy)(NCS)]+ cations and perchlorate counter anions. The copper centers are penta-coordinated by the four N atoms of the pmap or pzdepy and N(5) atom of the azide group in 2 and the thiocyanate group in 6. In the dinuclear unit [Cu2(L)(NCS)4] of 7, each copper atom forms bonds to three nitrogen atoms of the ligand L, [Cu N bonds from 2.013(2) to 2.054(2) A], and to N(4) and N(5) atoms of the two terminal thiocyanato groups [Cu(1) N(4) = 1.954(2) A; Cu(1) N(5) = 2.178(2) A]. The intradimer Cu(1)...Cu(1A) distance is 5.7010(14) A. An intramolecular π–π stacking with a ring–ring separation of 3.5991(14) A is observed between the central benzene ring and the pyridyl rings. In the three complexes (2, 6 and 7), the CuN5 chromophore may be described as an axially elongated square pyramid.

Two classes of novel dicyanamido (dca)–Cu(II) complexes were synthesized with a variety of tetradentate tripod amines, tridentate amines and diazacycloalkanes with pyridyl arms of different alkyl lengths and with tetra-aza macrocycles with different cavity sizes; the mononuclear, Cu(L)(dca)]ClO4 (L = tepa (1), TPA (2), pzdepy (4), hpzpy2 (5), cyclen (7), cyclam (8), tacp (9)) or Cu(L)(dca)ClO4 (L = MeDPA (10), Mepea (11)) and the dinuclear, [Cu2(L′)2(dca)](ClO4)3 (L′ = pmap (3), pzpy2 (6)). The isolated complexes were structurally characterized by electronic and IR spectroscopy as well as by X-ray. Single crystal X-ray diffraction analysis of the complexes [Cu(tepa)(dca)]ClO4 (1), [Cu(TPA)(dca)]ClO4 (2) and [Cu(pzdepy)(dca)]ClO4 (4) reveal their monomeric penta-coordinate nature with the isolated [Cu(L)(dca)]+ cations and ClO 4 − counter ions. All the complexes with the exception of 2 adapt distorted square pyramidal geometry while the coordination polyhedron around the copper center in 2 may be described as a distorted trigonal bipyramidal stereochemistry. The visible spectra of the complexes in aqueous solutions or in methanol are in complete agreement with the assigned X-ray geometry around the Cu(II) centers.

Three new polymeric zinc(II) azido complexes, namely [Zn(N 3 ) 2 (3-Brpy)] n ( 1 ), [Zn(N 3 ) 2 (4-Etpy)] n ( 2 ) and [Zn 2 (N 3 ) 4 (2,5-dmpyz)] n ( 3 ), where Brpy = bromopyridine, Etpy = ethylpyridine and dmpyz = dimethylpyrazine have been prepared and structurally characterized. The IR spectra of these complexes are measured and discussed. The structures of 1 and 2 are similar and feature one-dimensional zigzag chain of [Zn(N 3 ) 2 ] n in which each zinc atom is surrounded by double di-end on (EO) bridging azido ligands forming cyclic Zn 2 N 2 units. Furthermore, each zinc atom links a N hetero atom of the pyridine moiety leading to ZnN 5 chromophore. The geometry around the zinc center is best described as distorted trigonal bipyramid. Although complex 3 consists of the 1D chain of [Zn(N 3 ) 2 ] n with double di-EO azido bridges around each zinc center with almost planar Zn 2 N 2 cyclic units, the pyrazinic moiety behaves as a bidentate bridging N , N ′-ligand that binds the zinc centers across the [Zn 2 (N 3 ) 2 ] n chains extending the structure to be two-dimensional sheets. The Zn … Zn distances within the Zn 2 N 2 units are similar, fall within the range of 3.20–3.26 A, and the azido ligands are asymmetric and linear within experimental error in all of these three complexes.

The reaction between zinc(II) azide, Zn(N3)2 and aminopyrazine (ampyz) afforded the complexes: [Zn(N3)2(ampyz)2] (1), [Zn(N3)2(ampyz)]n (2) and [Zn3(N3)6(ampyz)2]n (3). These complexes are characterized by spectroscopic and crystallographic methods. The IR spectra of these compounds are measured and discussed. The structure of 1 consists of isolated tetrahedral zinc atom surrounded by two mono-dentate N-ampyz and two terminal azido ligands. Complex 2 features a zigzag chain of zinc centers in which each zinc is surrounded by alternate di-EO (end-on) and di-EE (end-to-end) azide bridges, the chain thus contains alternate four-membered Zn2N2 and eight-membered Zn2(NNN)2 rings. The two ampyz ligands are located in cis-arrangement and each of them further binds another zinc atom giving rise to a 3D network. Complex 3 contains two structurally different zinc atoms; the six-coordinate Zn(1) center links two di-EO azido bridges and two trans ampyz, thus having ZnN6 chromophore. The five-coordinate Zn(2) center binds two di-EO bridging azido groups and the fifth position is occupied by an N atom from a bridging ampyz molecule. Both zinc centers, therefore participate in the formation of a 1D chain of cyclic Zn2N2 units. Each ampyz ligand binds another zinc atom via the second pyrazinic N atom giving another cross-chain and thus the structure consists of 2D sheets. In these three complexes the azido ligands of all types are asymmetric and linear within the experimental error.

Four new cadmium(II) complexes: [Cd(4-Etpy) 2 (N 3 ) 2 ] n ( 1 ) (4-Etpy = 4-ethylpyridine), [Cd(3-acpy) 2 (N 3 ) 2 ] n ( 2 ) (3-acpy = 3-acetylpyridine), [Cd(4-OHMepy) 2 (N 3 ) 2 ] n ( 3 ), (4-OHMepy = 4-hydroxymethylpyridine) and [Cd(3-OHMepy) 2 (N 3 ) 2 ] n ( 4 ), (3-OHMepy = 3-hydroxymethylpyridine), are synthesized and structurally characterized. The IR spectra of the complexes are measured and discussed. The single crystal X-ray diffraction revealed that all of these four complexes exhibit 1D [Cd 2 (N 3 ) 2 ] n chains, six-coordinate cadmium centers and trans arrangement of the two pyridines. In the structure of 1 , the azide groups in the double bridges are alternately in the μ-1,3 and μ-1,1 modes between neighboring cadmium atoms, whereas in 2 the chain is formed only from double μ-1,1 azide bridges. In the structure of 3 , the double azido bridges show the unprecedented –Cd-(μ-1,1-N 3 ) 2 –Cd-(μ-1,1-N 3 ) 2 –Cd-(μ-1,1-N 3 ) 2 –Cd-(μ-1,3-N 3 ) 2 –Cd– sequence. In the structure of 4 , each pair of cadmium centers is simultaneously bridged by two different azides: μ-1,1 and μ-1,3 bridges. In the chain of polyhedra these μ-1,1 and μ-1,3 azido bridges are trans to each other. In all of the four complexes the μ-1,1 azides are asymmetric whereas the μ-1,3 azido ligands are more symmetric, and the azides of both types are almost linear within the experimental error.

Two series of Cu(II)–picolinato complexes of 1:1 and 3:2 Cu(II)-amine/picolinate namely [Cu(L 1 )(pic)]ClO 4 and [Cu 3 (L 2 ) 3 (pic) 2 (H 2 O)](ClO 4 ) 4 · x H 2 O or [Cu 3 (dpt) 3 (pic) 2 ](ClO 4 ) 4 , where pic = picolinate anion, L 1 = dien (diethylenetriamine), Et 2 dien ( N , N -diethyldiethylenetriamine), Medpt (3,3′-diamino- N -methyldipropylamine), L 2 = pmedien ( N , N , N ′, N ″, N ″-pentamethyl-diethylenetriamine), TPA (tris(2-pyridylmethyl)amine), and dpt = dipropylenetriamine were synthesized and structurally characterized by electronic and IR spectroscopy. Single crystal X-ray diffraction analysis of the complex [Cu(dien)(pic)]ClO 4 ( 1 ) reveals its monomeric nature whereas for [Cu 3 (pmedien) 3 (pic) 2 (H 2 O)](ClO 4 ) 4 ·2H 2 O ( 4 ), it was shown that the complex consists of two subunits of the mononuclear [Cu(pmedien)(pic)] + and the dinuclear [Cu 2 (pmedien) 2 (pic)(H 2 O)] 3+ cations with the perchlorate as counter ions and lattice water molecules. In the mononuclear complexes of 1 and 4 the picolinato anions act as N , O -chelating ligands, whereas N , O , O ′-picolinato bridges are observed in the dinuclear [Cu 2 (pmedien) 2 (pic)(H 2 O)] 3+ cations of 4 . The aqueous visible spectra of the complexes 1 – 6 are consistent with five-coordinate Cu(II) species where distorted square pyramidal geometry (SP) was assigned for complexes 2 – 5 , trigonal bipyramidal geometry (TBP) for 6 and an intermediate geometry between SP and TBP for 1 .

Two new coordination polymers of copper(I) chloride and pyrazinic acid (pyz-H), namely [CuCl(pyz-H)2]·2H2O (1) and [Cu2Cl2(pyz)(H2O)]·H2O (2) have been prepared and characterized by spectroscopic, magnetic and crystallographic methods. The overall physical measurements suggest that 1 is diamagnetic and contains monodentate N-pyrazinic acid, whereas 2 is paramagnetic and contains tridentate N,N′,O- chelating bridging pyrazinato anion. In the structure of 1 as elucidated by X-ray single crystal analysis, the asymmetric units [CuCl(pyz)2] are linked together forming a zigzag chain with tetrahedral copper(I) environment. The two lattice water molecules form hydrogen bonds with the uncoordinated N atom and carboxylate group O atom of pyz-H molecules. The Cu–N bond lengths are 2.009(6) A and Cu–Cl distances are 2.337(2) A. Complex 2 has a three-dimensional structure with the chains [Cu(I)Cu(II)(C5H3N2O2)Cl2(H2O)] interconnected by [Cu(I)Cl2N] tetrahedral unit and [Cu(II)NO2Cl2] polyhedra. The Cu(I)–Cl and Cu(I)–N distances are 2.327(2)–2.581(2) A and 1.988(6) A, respectively, whereas the Cu(II)–Cl and Cu(II)–N bond lengths are 2.258(2), 2.581(2) A, and 2.017(6) A, respectively. Hydrogen bonds of the type O–H⋯O are formed between lattice and coordinated water, and carboxylate oxygens of pyrazinato ligand giving rise to a three-dimensional network. The Cl− anions act as bridging ligands in both complexes. The magnetic data of complex 2 have been measured from 2 to 300 K and discussed.

Two new lanthanide complexes of isonicotinic acid N-oxide (HL), namely [Ln(L)2(H2O)4]n·(NO3)n·n(H2O) for Ln = Sm or Tb, have been synthesized and characterized by spectroscopic and crystallographic methods. IR spectra suggest that isonicotinic acid N-oxide acts as a O,O′-bidentate ligand, the N-oxide group as well as the nitrate group are not involved in coordination. Single crystal analyses have shown that both complexes are isomorphous, where the Ln(III) centers are eight coordinated by four O atoms of four water ligands and other four O atoms of two isonicotinic acid N-oxide ligands. The carboxylate groups are only involved in the bidentate syn–syn bridging mode into infinite chains. Hydrogen bonds between aqua ligands, lattice molecules, nitrate and N-oxide groups are formed giving a three-dimensional network.

A new series of mononuclear azido- and dicyanamido-Cu(II) complexes, [Cu(L)(N3)]ClO4 where L = pdpa {N-(2-aminopropyl)-N,N-bis(2-pyridylmethyl)amine}, Me3tren {tris(N-methyl-2-aminoethyl)amine} and Me6trien (1,1,4,7,10,10-hexamethyltriethylenetetraamine) and Cu(L)(C2N3)2 with L = pmedien (N,N,N′,N″,N″-pentamethyldiethylenetriamine) and Me2dpt (N,N-dimethyldipropyltriamine) were synthesized and structurally characterized by electronic and IR spectroscopy as well as by X-ray. Single crystal X-ray diffraction analysis of the complexes [Cu(pdpa)(N3)]ClO4 (1), [Cu(Me3tren)(N3)]ClO4 (2) and [Cu(pmedien)(C2N3)2] (3) reveals their monomeric nature. The structures of the complexes 1 and 2 derived from the blocking tripod tetraamines pdpa and Me3tren consist of isolated [Cu(L)(N3)]+ cations and Cl O 4 − counter ions. The copper centers are penta-coordinated by the four N of the amine ligands with the monodentate azido ligand occupying the apical site in distorted trigonal bipyramidal (TBP) geometry. Complex 1 exhibits π–π stacking interaction between the pyridyl groups. In the neutral complex 3, where the blocking ligand, pmedien is a linear tridentate amine the penta-coordinate geometry of the complex was achieved by the three planar amine-N and two terminal nitrile-N atoms from the two dicyanamide groups; one N in the basal position from the first dicyanamido group and one N at the apical position from the second group. The coordination polyhedron around the copper center may be described as an axially elongated square pyramidal (SP). The visible spectra of the complexes in aqueous solutions are in complete agreement with the assigned X-ray geometry around the Cu(II) centers.

The crystal structure of tricesium hexaazidolanthanate (III), Cs3La(N3)6, was determined by single crystal X-ray diffraction: triclinic, a=944.5(3) pm, b=948.4(2) pm; c=1010.5(3) pm, α=98.58(2)°, β=110.13(2)°, γ=102.12(2)°, space group P 1 , Z=2. Lanthanum is coordinated to nine azide groups. The polyhedra around two La atoms are related by a centre of symmetry and share two nitrogen atoms and two azide groups. The cesium atoms are surrounded by seven, eight and nine azide groups, respectively.

Solid azides of the types Cs 3 La(N 3 ) 6 , Cs 2 Nd(N 3 ) 5 , and Cs 4 Nd(N 3 ) 7 can be prepared by metathetical reactions under special precautions. Electronic spectra in diffuse reflectance, infrared and Raman spectra, and magnetic susceptibilities versus temperature and field strength were measured on microcrystalline samples. The data of these new compounds are primarily discussed in view of vibrational properties of the azide ion N 3 − , as ligand and in relation to first insights into the nature of the metal-nitrogen bonds within the coordination polyhedra of La(III) and Nd(III).