Syntheses, spectroscopic properties and crystal structures of two organoruthenium (II) complexes of bipyridines: [{Cp*Ru(2,2′-bipy)}2(μ-Cl)][PF6] and [{(η-p-cymene)Ru}2(μ-OH)2(4,4′-bipy)]2[BF4]4

Interaction of [Cp*RuCl(μ-Cl)]₂ with 2,2′-bipyridine (2,2′-bipy) in the presence of Na[PF₆] gave a chloride bridging dinuclear complex [{Cp*Ru(2,2′-bipy)}₂(μ-Cl)][PF₆] (1). In the crystal structure, the cation [{Cp*Ru(2,2′-bipy)}₂(μ-Cl)]⁺ contains a bent Ru-Cl-Ru linkage with an angle of 141.87(12)°. The tris(μ-hydroxo)diruthenium complex [{(η⁶-p-cymene)Ru}₂(μ-OH)₃][BF₄] in acetone solution was treated by 4,4′-bipyridine (4,4′-bipy) to give a hydroxo-bridged tetranuclear complex [{(η⁶-p-cymene)Ru}₂(μ-OH)₂(μ-4,4′-bipy)]₂[BF₄]₄ (2). Complex 2 consists of four (η⁶-p-cymene)Ru moieties connected by two 4,4′-bipy and four hydroxo-bridging groups, forming a novel metallomacrocycle with alternating hydroxyl and 4,4′-bipy bridges between the ruthenium atoms. Spectroscopic properties along with electrochemistry of two organoruthenium (II) complexes 1 and 2 are reported.     

Chiral diruthenium(II) complexes containing a modified 4,4-bipyridine bridging ligand: syntheses, characterization and DNA binding

A pair of novel chiral dimeric ruthenium(II) complexes [ΔΔ-, ΛΛ-Ru(bpy)₂(btpb)Ru(bpy)₂]⁴⁺ (1; btpb=2,2^′-bis(1,2,4-triazino[5,6-f]phenanthren-3-yl)-4,4^′-bipyridine) have been synthesized and characterized by electrospray mass spectra, ¹H NMR, UV-Vis and circular dichroism spectra. Binding behaviors of the complexes with calf thymus DNA have been investigated by absorption spectra and viscosity measurements. The electronic absorption spectrum of ΔΔ-1 at 505.5 nm exhibits hypochromism of about 8.4% and bathochromism of 2.5 nm; ΛΛ-1 at 500.0 nm exhibits hypochromism of about 9.1% and bathochromism of 4.5 nm, respectively. The experiments suggest that ΔΔ-1 and ΛΛ-1 may be bound to DNA by non-intercalating binder.     

Synthesis, characterization and crystal structure of a monomeric and a macrocyclic copper (II) complex with a large cavity using benzylacetylacetone ligand

The bidentate ligand benzylacetylacetone was used to synthesize the Cu(II) complexes 1 and 2 without and with 4,4^′-bipyridine ligand, respectively. The complexes were characterized by analytical and spectroscopic studies. The mononuclear complex [Cu(C₁₀H₉O₂)₂] (1) has been synthesized by the reaction of copper acetate with the ligand whereas the tetranuclear complex [Cu₄(4,4^′-bpy)₄(C₁₀H₉O₂)₄(C₂H₃O₂)₄] (2) has been synthesized by the reaction of copper acetate with the ligand followed by the addition of 4,4^′-bipyridine. The X-ray analysis shows that the complex 1 has square planar geometry and the complex 2 has square pyramidal geometry around the metal centers. The thermogravimetric studies showed that the complexes undergo decomposition in multiple steps.     

Syntheses and characterization of luminescent dinuclear and polynuclear Cu(I) complexes containing 4,4′-bis(diphenylphosphino)biphenylene bridge

The dinuclear complex [Cu₂(dpbp)₂(NCMe)₄][BF₄]₂ (1) has been prepared by treating [Cu(NCMe)₄][BF₄] with 4,4′-bis(diphenylphosphino)biphenylene (abbreviated as dpbp). Reactions of 1 with 2,2′-bipyridine and 1,1′-bis(diphenylphosphino)ferrocene (abbreviated as dppf) afford [Cu₂(dpbp)₂(2,2′-bipy)₂][BF₄]₂ (2) and [Cu₂(dpbp)(dppf)₂][BF₄]₂ (3), respectively. In contrast, compound 1 reacts with tetra(2-pyridyl)ethyl-1,4-diaminobutane (abbreviated as tpyda) to produce the polymeric complex {[Cu₂(dpbp)(tpyda)][BF₄]₂}_n (4). Compounds 1-4 are photoluminescent with the emission band (λ_max) in the range 510-554 nm. The crystal structures of 1 and 4 have been determined by an X-ray diffraction study.     

Formation of coordination polymer and molecular complex of 4,4′-bipyridyl-N,N′-dioxide of manganese and zinc

A 1D-coordination polymer [{Mn₃(C₆H₅COO)₆(BPNO)₂(MeOH)₂}(MeOH)₂]_n (1) having benzoate as the anionic ligand and 4,4′-bipyridyl-N,N′-dioxide (BPNO) as bridging ligand is synthesized by reacting benzoic acid with manganese(II) acetate tetrahydrate followed by reaction with 4,4′-bipyridyl-N N′-dioxide. The bridging bidentate BPNO ligands in this coordination polymer along with the benzoate bridges hold the repeated units. The chain like structure in one dimension by benzoate bridges are connected to each other through the μ³-η²:η¹ bridges of BPNO ligands. This coordination polymer can be transformed to a molecular complex [Mn(H₂O)₆](C₆H₅COO)_2.4BPNO (2). In this complex the BPNO remains outside the coordination sphere but they are hydrogen bonded to water molecules to form self assembled structure. The reaction of 3,5-pyrazoledicarboxylic acid (L₁H2) and BPNO with manganese(II) acetate or zinc(II) acetate led to molecular complexes with composition [M₂(L₁)₂(H₂O)₆].BPNO·xH₂O {where M = Mn(II) (3), Zn(II)(4)}. These molecular complexes of BPNO are characterised by X-ray crystallography. The complexes 3-4 are binuclear carboxylate complexes having M₂O₂ core formed from carboxylate ligands with two metal ions.     

Synthesis and properties of red emitter Ru(II) complexes based on 6,6′-disubstituted-4,4′-bipyrimidine

Heteroleptic complexes [Ru(bpy)₂(R₂bpm)]²⁺, where bpy = 2,2′-bipyridine and R₂bpm = 6,6′-diaryl-4,4′-bipyrimidine, have been synthesized and characterized, together with the homoleptic complex [Ru(R₂bpm)₃]²⁺, in which R₂bpm = 6,6′-diphenyl-4,4′-bipyrimidine. The substituent aryl on the bipyrimidine has significant effects on the properties of these complexes as compared to the parent [Ru(bpy)₂(bpm)]²⁺ complex. The complexes exhibit Ru-to-bpm charge transfer (CT) absorptions centered at about 540 nm and Ru-to-bpy CT absorptions centered at about 435 nm. The assignment of the low energy absorptions is supported by the relative ease of the reduction of the new complexes as compared to [Ru(bpy)₃]²⁺. The new complexes exhibit a relatively intense emission at room temperature, with lifetimes in the 10-50 ns range, with the homoleptic species exhibiting the higher-energy (maximum at 724 nm) and the longest-lived (τ = 48 ns) emission among the complexes. Luminescence lifetimes and quantum yields are governed by the energy gap law, indicating that direct deactivation to the ground state is the dominant relaxation pathway for 1-6, while thermally activated processes are inefficient.     

Versatile reaction of the potential host system [(Me3Sn) 4Ru(CN) 6]∞ with 4-thiopyridone/4-mercaptopyridine in water

Single crystals of three derivatives of the structurally still incompletely characterized coordination polymer [(Me₃Sn)₄Ru(CN)₆] 1b have been prepared and subjected to crystallographic studies: [1b · 4H₂O]=2b forms stacks of puckered _∞²[Ru{μ-CNSn(Me₃)NC}₂] sheets interlinked by hydrogen bonds in making use of two additional CNSn(Me₃)OH₂ ligands and quasi-zeolitic water. Mild drying of 2b leads to the “missing link” between 1b and 2b, [1b · 2H₂O], 3b. The structure of [1b · 2tp] (tp=4-thiopyridone) consists of a three-dimensional, negatively charged host framework comprising (via Sn-S bonds) one “aromatic” thione linkage and a [Me₃Sn · tp]⁺guest ion involving a more zwitterionic form of tp. Slow uptake of Me₃SnCl from the gas phase by an aqueous solution of K₄[Ru(CN)₆] and tp afforded the novel assembly [1b · 2H₂O · 0.8pms · 0.2pds] (pms/pds=4,4^′-dipyridylmono-/disulfide), the supramolecular architecture of which resembles that of 2b. Bridging pms or pds molecules occupy equivalent interlayer sites, and the pms/pds ratio is likely to vary. At least three further assemblies containing again 1b and either tp or pds/pms have likewise been isolated, however, not as single crystals.     

Acetato and formato copper(II) complexes with 4,4′-dimethyl-2,2′-bipyridine and 5,5′-dimethyl-2,2′-bipyridine: Synthesis, crystal structure, magnetic properties and EPR results. A new 1D polymeric water chain

By the reactions of Cu(AcO)₂·H₂O and Cu(HCOO)₂·4H₂O with 4,4′-dimethyl-2,2′-bipyridine and 5,5′-dimethyl-2,2′-bipyridine the compounds [Cu(AcO)₂(4,4′-Me₂-2,2′-bipy)]·1/2H₂O (1), [Cu(AcO)₂(5,5′-Me₂-2,2′-bipy)(H₂O)] (2), [Cu(HCOO)(μ-HCOO)(4,4′-Me₂-2,2′-bipy)]_n·nH₂O (3) and [Cu(HCOO)(μ-HCOO)(5,5′-Me₂-2,2′-bipy)]_n·2nH₂O (4) were obtained. In the acetate complexes, 1 and 2, the geometry around copper is distorted octahedral and square pyramidal, respectively. Dimeric units of different geometry are formed in both cases through hydrogen bonds in which non-coordinated (in 1) and coordinated (in 2) water molecules are involved. The structures of 3 and 4 consist of polymeric monodimensional chains of square pyramidal copper units linked by axial-equatorial syn-anti (3) or anti-anti (4) bridging formate groups. Water molecules form hydrogen bonds with formate groups of the same chain in compound 3. In compound 4 the water molecules link the polymeric contiguous chains of complex through hydrogen bonds with oxygen atoms of formate groups and they are also linked between them, forming monodimensional water chains which run parallel to the complex chains. Sheets parallel to the ac plane are formed by alternating chains of water and polymeric complex. Magnetic properties and EPR spectra for these compounds have been studied.     

Mixed ligand complexes of osmium(II)-2,2-bipyridine: synthesis, spectral characterization and electrochemical properties of bis-chelated-arylazoimidazole-bipyridine-osmium(II) and X-ray crystal structure of [(2,2-bipyridine)-bis-{1-methyl-2-(p-tolylazo)imidazole}osmium(II) hexafluorophosphate

Reaction of ctc-OsBr₂(RaaiR^′)₂ [RaaiR^′=1-alkyl-2-(arylazo)imidazole, p-R-C₆H₄-NN-C₃H₂-NN-1-R^′, where R=H (a), Me (b), Cl (c) and R^′=Me (2), Et (3) and CH₂Ph (4)] with 2,2^′-bipyridine (bpy) in presence of AgNO₃ in EtOH followed by the addition of NH₄PF₆ afforded a mixed ligand complex [Os(bpy)(RaaiR^′)₂](PF₆)₂. The structure of the complex, in one case [Os(bpy)(MeaaiMe)₂](PF₆)₂ · 4H₂O, has been confirmed by X-ray crystallography. The complexes are diamagnetic (low spin d⁶, s=0) and they show intense MLCT transition in the visible region (480-525 nm) and a weak transition at longer wavelength (>850 nm) in CH₃CN solution. Cyclic voltammetry of the complexes show two metal oxidation, Os(II)/Os(III) at 0.72-0.76 V and Os(III)/Os(IV) at 1.34-1.42 V and three successive ligand reductions.     

2D Holodirected lead(II) bromide coordination polymers constructed of rigid and flexible ligands

Three new 2D Pb^II coordination polymers containing 4,4′-bipyridine (4,4′-bipy), 1,2-bis(4-pyridyl)ethane (bpa) and 1,2-bis(4-pyridyl)ethene (bpe) with bromide anions, [Pb(μ-4,4′-bipy)(μ-Br)₂]_n (1), [Pb(μ-bpa)(μ-Br)₂]_n (2) and [Pb(μ-bpe)(μ-Br)₂]_n (3) have been synthesized and characterized by elemental analysis, IR spectroscopy and their structures studied by X-ray crystallography. The thermal stability of compounds 1-3 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The single-crystal X-ray data shows that the Pb²⁺-ions have coordination numbers of six and contain the rarely holodirected geometries.     

Aromatic N-oxide bridged copper(II) coordination polymers: Synthesis, characterization and magnetic properties

The complexes [Cu₂(o-NO₂-C₆H₄COO)₄(PNO)₂] (1), [Cu₂(C₆H₅COO)₄(2,2′-BPNO)]_n (2), [Cu₂(C₆H₅COO)₄(4,4′-BPNO)]_n (3), [Cu(p-OH-C₆H₄COO)₂(4,4′-BPNO)₂·H₂O]_n (4), (where PNO = pyridine N-oxide, 2,2′-BPNO = 2,2′-bipyridyl-N,N′-dioxide, 4,4′-BPNO = 4,4′-bipyridyl-N,N′-dioxide) are prepared and characterized and their magnetic properties are studied as a function of temperature. Complex 1 is a discrete dinuclear complex while complexes 2-4 are polymeric of which 2 and 3 have paddle wheel repeating units. Magnetic susceptibility measurements from polycrystalline samples of 1-4 revealed strong antiferromagnetic interactions within the {Cu₂}⁴⁺ paddle wheel units and no discernible interactions between the units. The complex 5, [Cu(NicoNO)₂·2H₂O]_n·4nH₂O, in which the bridging ligand to the adjacent copper(II) ions is nicotinate N-oxide (NicoNO) the transmitted interaction is very weakly antiferromagnetic.     

Ruthenium(II/III) mediated transformation of 1,2-bis(2′-pyridylmethyleneimino)benzene (L) to 2-(2′-benzimidazolyl)pyridine (L′H) and its in situ formed complexes with Ru(II): X-ray structure of trans-[Ru(PPh3)2(L′H)2](ClO4)2

A series of ruthenium (II) complexes of formulae trans-[Ru(PPh₃)₂(L′H)₂](ClO₄)₂ (1), [Ru(bpy)(L′H)₂](ClO₄)₂ (2), [Ru(bpy)₂(L′H)](ClO₄)₂ (3), cis-[Ru(DMSO)₂(L′H)₂]Cl₂ (4), and [Ru(L′H)₃](PF₆)₂ (5) (where L′H = 2-(2′-benzimidazolyl)pyridine) have been synthesized by reaction of the appropriate ruthenium precursor with 1,2-bis(2′-pyridylmethyleneimino)benzene (L). The complexes were characterized by elemental analyses, spectroscopic and electrochemical data. All the complexes were found to be diamagnetic and hence metal is in +2 oxidation state. The molecular structure of trans-[Ru(PPh₃)₂(L′H)₂](ClO₄)₂ has been determined by the single crystal X-ray diffraction studies. The molecular structure shows that Ru(II) is at the center of inversion of an octahedron with N₄P₂ coordination sphere. The ligand acts as a bidentate N,N′donor. The electronic spectra of the complexes display intense MLCT bands in the visible region.Cyclic voltammetric studies show quasi-reversible oxidative response at 0.99-1.32 V (vs Ag/AgCl reference electrode) due to Ru(III)/Ru(II) couple.     

β-Diiminatolanthanoid(III) halides revisited

The crystalline compounds [LnCl₂(L)(thf)₂] [Ln = Ce (1), Tb (2), Yb (3)], [NdI₂(L)(thf)₂] (4), [LnCl(L′)₂] [Ln = Tb (5), Yb (6) (a known compound)] and [YbCl(L′′)(μ-Cl)₂Li(OEt₂)₂] (7) have been prepared [L = {N(C₆H₃Prⁱ₂-2,6)C(H)}₂CPh, L′ = {N(SiMe₃)C(Ph)}₂CH, L′′ = {N(SiMe₃)C(C₆H₄Ph-4)}₂CH]. The X-ray molecular structures of 2-7 have been established; in each, the monoanionic ligand L, L′ or L′′ is N,N′-chelating and essentially π-delocalised. Each of 1-7 was prepared from the appropriate LnCl₃, or for 4 [NdI₃(thf)₂], and an equivalent portion of the appropriate alkali metal [Li for 7, Na for 2, 3 and 5, or K for 1, 4 and 6] β-diiminate in thf; the isolation of exclusively 5 and 6 (rather than the L′ analogues of 2 or 3) is noteworthy, as is the structure of 7 which has no precedent in Group 3 or 4f metal β-diiminato chemistry.     

Dinuclear copper(I) complexes containing diimine and phosphine ligands: Synthesis, copper-copper separation and photophysical properties

Dinuclear copper(I) complexes with bridging bis(dicyclohexylphosphino)methane (dcpm) or bis(diphenylphosphino)methane (dppm) and 2,2′-bipyridine or 2-[N-(2-pyridyl)methyl]amino-5,7-dimethyl-1,8-naphthyridine (L), [Cu₂(bpy)₂(dppm)₂](BF₄)₂ (1), [Cu₂(bpy)₂(dcpm)](BF₄)₂ (2), [Cu₂(L)(dppm)](BF₄)₂ (3) and [Cu₂(L)(dcpm)](BF₄)₂ (4) were prepared, and their structures were determined by X-ray crystal analysis. Two-, three-, and four-coordinate copper(I) centers are found in these complexes. Compounds 3 and 4 show close Cu^I?Cu^I separations of 2.664(3) and 2.674(1) Å, respectively, whereas an intramolecular copper-copper distance of 3.038 Å is found in 2 having only dcpm as an additional bridge. Powdered samples of 1, 3, and 4 display intense and long-lived phosphorescence with λ_max at 533, 575, and 585 nm at room temperature, respectively. In the solid state, 2 exhibits only a weak emission at 555 nm. The time-resolved absorption and emission spectra of these complexes were investigated. The difference in the emission properties among complexes 1-4 suggests that both Cu^I?Cu^I distances and coordination environment of the copper(I) centers affect the excited-state properties.     

Photoluminescent coordination polymers of d metals with 4,4′-dipyridylsulfide (dps)

Reactions of AgClO₄, Zn(CH₃COO)₂ · H₂O and CuI with the ligand 4,4′-dipyridylsulfide (dps) in 1:1 ratio give rise to coordination polymers 1-3 and 5, the structures of which were characterized by X-ray crystallography. Polymers [Ag₂(dps)₂](ClO₄)₂ · MeCN (1) and [Ag₂(dps)₂(μ₂-MeCN)(MeCN)](ClO₄)₂ · MeCN · H₂O (2) are pseudo-supramolecular isomers, differing from each other in the coordination geometry of silver atom and the packing pattern. Both 1 and 2 are zigzag coordination polymers bridged by weak Ag?Ag, Ag?S or Ag?NC-CH₃ interactions to form double stranded coordination polymers. While [Zn(dps)(CH₃COO)₂] (3) is a zigzag single stranded coordination polymer, [Zn(dps)₂(H₂O)₂](ClO₄)₂ · H₂O (4) is an unusual mononuclear complex with a box-like structure. Interesting intermolecular hydrogen bonding present in the compounds 3 and 4 leads to 3D hydrogen-bonded network structure.Coordination polymer [Cu₂I₂(dps)₂] (5) is a non-interpenetrating (4,4) net. Photoluminescence properties of the compounds 1-5 have been examined in solid states at room temperature. These compounds have been found to exhibit yellow and blue photoluminescence.     

The key role of hydrogen bonding in the nuclearity of three copper(II) complexes with hydrazone-derived ligands and nitrogen donor heterocycles

Three new Cu(II) complexes of formula [Cu(L¹)(pyz)(CH₃OH)]ClO₄ (1), [Cu(L¹)(4,4′-bpy)(ClO₄)]·0.5H₂O (2) and [{Cu(L²)(ClO₄)}₂(μ-4,4′-bpy)] (3) have been synthesised by using pyrazine (pyz) and 4,4′-bipyridine (4,4′-bpy) and tridentate O,N,O-donor hydrazone ligands, L¹H and L²H, obtained by the condensation of 1,1,1-trifluoro-2,4-pentanedione with salicyloylhydrazide and benzhydrazide, respectively. The ligands and their complexes have been characterized by elemental analyses, FT-IR, and UV-Vis spectroscopies. Single crystal X-ray structure analysis evidences the metal ion in a slightly deformed square pyramidal geometry in all the complexes. However complexes 1 and 2 are mononuclear with pyz and 4,4′-bpy, respectively, showing an unusual monodentate behavior, while complex 3 is dinuclear with 4,4′-bpy adopting the typical bridging coordination mode. Self assembly of the complex units by hydrogen bonding interactions produces one-dimensional arrangement in each crystal packing. The magnetic characterization of complex 3 indicates a weak antiferromagnetic exchange interaction between the Cu(II) ions (J = −0.96 cm⁻¹) mediated through the long 4,4′-bpy bridge. Electrochemical behavior of the complexes is also discussed.     

Second-ligand-dependent multi-fold interpenetrated architectures of two 3-D metal(II)-organic coordination polymers

By one-pot solvothermal reaction, two 3-D metal(II)-organic coordination polymers [Zn₂(SDC)₂(L¹)] (1) and [Zn(SDC)(L²) · 2DMF] (2) are self-assembled from trans-4,4′-stilbenedicarboxylic acid (H₂SDC), 4-(4-((E)-2-(pyridin-4-yl)vinyl)- styryl)pyridine (L¹), 4,4′-bipyridine(L²) and zinc salts in the presence of N,N′-dimethylbenzenamine, and characterized by single-crystal X-ray diffraction analyses. The overall structure of 1 with total potential solvent-accessible volume of 44.2% presents a fourfold interpenetrated topology from 6-connected CdO-like nets, while that of 2 with nanosized channels occupied by free DMF molecules displays a fivefold interpenetrated framework of [Zn(SDC)(L²)]_n from 4-connected diamondoid networks. The topology types and the multi-fold interpenetrating of 1 and 2 are dependent on the second ligands (L¹ and L²). Solid-state 1 and 2 have expected photoluminescence with maximum emission at 484 and 505 nm, respectively.     

Construction of one-, two- and three-dimensional Cu(I) polymeric architectures containing bis(diphenylphosphino)acetylene and 4,4′-bipyridine linking ligands

One-dimensional {[Cu₂(dppa)₂(4,4′-bipy)(CH₃CN)₂](BF₄)₂ · 2CH₃CN}_n (1), two-dimensional {[Cu₂(dppa)(4,4′-bipy)₂(CH₃CN)₂](BF₄)₂ · 4CH₂Cl₂ · 4H₂O}_n (2) and three-dimensional {[Cu₂(dppa)(4,4′-bipy)₃](BF₄)₂ · 2CH₂Cl₂ · 3CH₃CN · 3H₂O}_n (3) polymeric complexes have been prepared by self-assembly of [Cu(MeCN)₄]BF₄, Ph₂PCCPPh₂ (dppa) and 4,4′-bipyridine (4,4′-bipy) in a 2:2:1, 1:1:1 and 2:2:3 molar ratio, respectively. The structures of 1-3, determined by an X-ray diffraction study, reveal a linear spring-like architecture for 1, a planar honeycomb grid for 2 and an interlocked adamantoid network for 3.     

Synthesis, structure and magnetic studies of two-dimensional network of Cu(II) polymer using malonate and 4,4′-azobispyridine ligands

The malonato-bridged copper(II) complex [Cu(mal)(H₂O)(azpy)_1/2] · H₂O (1) (mal = malonate, azpy = 4,4′-azobispyridine) has been synthesized and characterized by X-ray diffraction. The structure of 1 consists of malonato-bridged uniform copper(II) chains which are covalent connected through azpy to form two-dimensional wavelike network. The magnetic pathway of complex 1 is through a single syn-anti carboxylate bridge connecting equatorial and equatorial positions of adjacent copper(II) atoms, and have the value of the intrachain ferromagnetic coupling (J = 8.73(3) cm⁻¹) and interchain antiferromagnetic coupling (zJ′ = − 1.31(1) cm⁻¹) through a numerical expression for a ferromagnetic uniform chain.     

Protonated 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine and its Fe(II) bischelates: Syntheses and molecular structures

Compounds of the molecular formulae, [LH₃](NO₃)₃ (1), [Fe(LH)₂](PF₆)₄·5H₂O (2), [Fe(L)₂][Fe(L)(LH)](PF₆)₅·H₂O (3), [Fe(L)₂][Fe(L)(LH)](BF₄)₅·2H₂O (4) and [Fe(L)₂](Cr₂O₇)·6H₂O (5) have been synthesized using 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine (L). The molecular structures of all the compounds were determined. The Fe(II) complexes are high spin in nature at room temperature and upon cooling a gradual spin-transition is observed. Among 1-5, hydrogen-bonding, π···π, and anion···π interactions as well as water tetramer and pentamer are present in the molecular packing.