Synthesis,Characterization and Properties of TbIII and DyIII Coordination Compounds based on Isomeric Ligands

Reactions of the isomeric ligands Hpztza [Hpztza = 5‐(2‐pyrazinyl)tetrazole‐2‐acetic acid] and Hpmtza [Hpmtza = 5‐(2‐pyramidyl)tetrazole‐2‐acetic acid] with TbCl₃ · 6H₂O or DyCl₃ · 6H₂O under solvothermal conditions afforded four mononuclear complexes, [Ln(pztza)₂(H₂O)₆] · pztza · 3H₂O [Ln = Tb ( 1 ), Dy ( 2 )] and [Ln(pmtza)₂(H₂O)₆] · Cl · 3H₂O [Ln = Tb ( 3 ), Dy ( 4 )]. The compounds were characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. X‐ray diffraction analyses reveal that all structures are mononuclear. The four compounds are self‐assembled to form three‐dimensional networks by hydrogen bonds. The different positions of the nitrogen atom control the coordination mode of the ligands and further influence the crystal structures. Furthermore, the luminescence properties were also investigated at room temperature in the solid state.     

Syntheses and Structures of Coordination Polymers Constructed by Semi‐Rigid Bicarboxylic Acid Ligands

The complexes [Co(L¹)(mpy)] ( 1 ), [Ni(L¹)(mpy)] ( 2 ), [Co(L¹)(tbpy)] · 2H₂O ( 3 ), [Ni₂(L¹)₂(tbpy)₂] · 5H₂O ( 4 ), [Mn₂(L¹)₂(tbpy)₂] · 3H₂O ( 5 ), [Mn(L¹)(biim‐3)] ( 6 ), [Ni₂(L¹)₂(btb)₂(H₂O)] · 2H₂O ( 7 ), [Cu(L²)(mpy)] · 7H₂O ( 8 ), [Co(L²)(tbpy)(H₂O)] ( 9 ), [Ni(L²)(tbpy)(H₂O)] · H₂O ( 10 ), [Cu(L²)(bib)] · 2H₂O ( 11 ), and [Cu(L²)(btb)] · 2H₂O ( 12 ) [H₂L¹ = (3‐carboxyl‐phenyl)‐(4‐(2′‐carboxyl‐phenyl)‐benzyl)ether, H₂L² = 3‐carboxy‐1‐(4′‐carboxybenzyl)‐2‐oxidopyridinium, mpy = 2‐(4‐(4′‐methylphenyl)‐6‐(pyrindin‐2‐yl)pyridin‐2‐yl)pyridine), tbpy = 2‐(4‐(4′‐tert‐butylphenyl)‐6‐(pyrindin‐2‐yl)pyridin‐2‐yl)pyridine), biim‐3 = 1,3‐bis(imidazol‐1′‐yl)propane, btb = 1,4‐bis(1,2,4‐triazol‐1‐ylmethyl)benzene, bib = 1,4‐bis(imidazol‐1′‐ylmethyl)benzene] were synthesized. Compounds 1 – 6 have similar 1D chain structures, which are further linked by π–π interactions to generate supramolecular double chains for 1 and 2 , and supramolecular layers for 3 – 6 . Compound 7 displays a 3D 6‐connected framework with (4⁴ · 6¹¹) topology. Compound 8 features a monomolecular structure, which is further linked by hydrogen bonds between the lattice water molecules and carboxylate oxygen atoms of L² anions to form a 2D supramolecular layer. The monomolecular structures of 9 and 10 are connected by hydrogen bonds and π–π interactions simultaneously to generate supramolecular layers. Compounds 11 and 12 show layer structures.     

Two Coordination Compounds Bearing Bis(2-dimethylaminoethyl) Ether: Syntheses,Crystal Structures and Catalytic Application to the Henry Reaction

Two novel coordination compounds, namely [Cu₂(BDMAEE)(CH₃COO)₄]_n(1) and[Ni(BDMAEE)Cl₂](2)[BDMAEE=bis(2-dimethylaminoethyl) ether], have been synthesized and characterized by IR, elemental analysis, PXRD and X-ray single crystal diffraction. In compound 1, the central Cu(Ⅱ) ion is coordinated with four oxygen atoms and one nitrogen atom, forming a distorted square pyramidal geometry. The asymmetric units composed of one Cu(Ⅱ) ion, two acetates and a half of BDMAEE are connected to form an infinite 1D chain structure by the bridging acetate and the BDMAEE. In compound 2, the central Ni(Ⅱ) ion is coordinated with one oxygen atom, two chlorine anions and two nitrogen atoms, forming a distorted square pyramidal geometry. The compounds exhibited excellent catalytic properties in the Henry reaction of nitromethane with some aromatic aldehydes, and the optimized reaction conditions were obtained.     

Syntheses and Crystal Structures of Two One-Dimensional Chain Copper Benzoylacetone Complexes Bridged Through Azobispyridine Ligands

Two copper complexes [Cu(bzac)₂(4,4′-azpy)]·H₂O (1) and [Cu(bzac)₂(3,3′-azpy)] (2) (bzac = benzoylacetone, 4,4′-azpy = 4,4′-azobispyridine, 3,3′-azpy = 3,3′-azobispyridine) have been synthesized and characterized. The crystal structures were determined by X-ray diffraction analysis. In crystals of Complexes 1 and 2, the copper atoms have distorted octahedral symmetry. The two compounds possess very similar one-dimensional linear chains linked through the rod-like 4,4′-azpy or 3,3′-azpy ligands.     

Synthesis,Structures, and Antibacterial Activities of Four Similar 1D Metal-organic Polymers with Different Metal Ions

Four similar 1D metal-organic polymers [Cd(impc)₂(H₂O)₂]_n ( 1 ), [Co(impc)₂(H₂O)₂]_n ( 2 ), [Mn(impc)₂(H₂O)₂]_n ( 3 ), and {[Cu(impc)₂] · [jy2H₂O}_n ( 4 ) based on an asymmetric 5-(1H-imidazole-l-yl)-3-pyridinecarboxylic acid (Himpc) were prepared hydrothermally and structurally characterized. According to the frontier molecular orbital (FMOs) calculations, the photoluminescence of 1 should be assigned as the n→π* transition. The antibacterial properties of 1 – 4 were studied. 1 exhibited good antibacterial activities towards B. subtilis and S. aureus with the smallest MIC value of 2 μg · mL^–1. Compared with Co^II, Mn^II and Cu^II ions, the polymer with Cd^II ion has the better antibacterial activity. Our work preliminarily reveals that the metal ions also have different influences on antibacterial activities of complexes.     

Coordination Polymers with Bipyridyl Diene and Triene Ligands: Synthesis,Structures and Luminescent Properties

Solvothermal reactions of cadmium salts with bipyridyl diene and triene ligands[1,3-bis((E)-2-(pyridin-4-yl)vinyl)benzene-(1,3-bpeb) and 1,6-bis(4-pyridyl)-1,3,5-hexatriene(bphte)] and one bipyridyl triene ligand[1,6-bis(4-pyridyl)-1,3,5-hexatriene-(bphte)] in the presence of auxiliary carboxylic acids including 2,6-dichlorobenzoic acid(2,6-HDCBA) and 2-naphthal-enecarboxylic acid(2-HNCA) gave rise to four coordination polymers[Cd(bphte)(2,6-DCBA)₂]_n(1), {[Cd(bphte)(2-NCA)₂]·5.8H₂O}_n(2),[Cd₂(1,3-bpeb)₂(2,6-DCBA)₄]_n(3) and {[Cd₄(1,3-bpeb)₄(2-NCA)₇(HCOO)]·     

Two Novel 3D Copper Phthalate Coordination Complexes Incorporating Isomeric Flexible Bis(pyridylformyl)piperazine Ligands

Two novel metal‐organic coordination complexes [Cu(3‐bpfp)(pht)(H₂O)] · 2H₂O ( 1 ) and [Cu₃(4‐bpfp)(pht)₂(OH)₂] · 2H₂O ( 2 ) were hydrothermally synthesized by self‐assembly of phthalic acid (H₂pht), flexible bis(pyridylformyl)piperazine ligands [3‐bpfp = bis(3‐pyridylformyl)piperazine, 4‐bpfp = bis(4‐pyridylformyl)piperazine], and copper chloride. Single crystal X‐ray diffraction analysis revealed that the adjacent Cu^II ions are connected by pht showing different coordination modes [a bis(monodentate) coordination mode for 1 and a monodentate‐bidentate coordination mode for 2 ] to form 1D Cu‐pht‐Cu chains in 1 and 2D Cu‐pht layers in 2 . In compound 1 , a twofold interpenetrated CdSO₄‐like topology is formed by connection of 3‐bpfp. Using the isomeric ligand 4‐bpfp instead of 3‐bpfp resulted in the formation of 2 , which displays a novel 3, 4, 4, 4‐connected tetranodal 3D coordination polymeric framework. The ligand 3‐bpfp adopts a μ₂‐bridging coordination mode in 1 (by ligation of the pyridyl nitrogen atoms), whereas the ligand 4‐bpfp adopts a μ₄‐bridging coordination mode (by ligation of pyridyl nitrogen and carbonyl oxygen atoms) in 2 . Moreover, the electrochemical properties of carbon paste electrodes bulk modified with the two copper complexes were studied.     

Synthesis and Crystal Structures of Two Zinc(II) Complexes with the Tripodal Ligand Tris(2-Benzimidazolymethyl)Amine

This article reports the synthesis and crystal structures of two new mononuclear Zinc(II) complexes, [Zn₂(NTB)₂(N₃)₂](NO₃)₂·2CH₃OH (1) and [Zn₂(NTB)₂(SCN)₂](NO₃)₂·2CH₃OH·H₂O (2). Complex 1 crystallizes in the triclinic system, space group P&1macr;, a=13.743(4), b=14.374(4), c=14.443(5) Å; α=77.053(5), β=81.824(5), γ=88.959(6)°; Z=2; R1=0.0418, wR2=0.0889. Complex 2 also crystallizes in the triclinic system, space group P&1macr;, a=12.203(10), b=14.430(12), c=18.541(15)Å; α=72.712(15), β=85.039(15), γ=73.610(14); Z=2; R1=0.0771, wR2=0.1288. In both cases the central zinc(II) metal ions are coordinated to the four nitrogen atoms of NTB and a nitrogen atom of N^- ₃(1) or SCN^-(2) to form distorted trigonal bipyramidal coordination spheres.     

Structures of Organo Alkali Metal Complexes and Related Compounds

The investigation of the reactivity and structure of organometallic compounds of alkali metals has experienced a blustering development in the last decades. This class includes compounds that are especially important for our understanding of chemical bonding and also quite simple, for example methyl alkali metal complexes, whose structures have been unequivocally determined. Organometallic compounds of alkali metals (and also magnesium) generally exist as ion aggregates whose properties can be significantly modified through solvation by, for example, ether or amines. Important advances in the synthesis of new compounds, especially those of the heavier alkali metals, have been based on these results. It was long believed that the alkali metals had little tendency to undergo coordination and that their coordination chemistry would offer few surprises. This picture has now changed completely. Results from crystal structure investigations have revealed a variety of often surprising structure types (rings, heterocubanes, chains, layers, etc.) not only with the organometallic compounds but also with the amides, imides, alkoxides, phenoxides, enolates, and even halides. A comparison reveals interesting similarities between compounds that appear to be so different and leads to a general classification of the structure types possible with C, N, O, and halo ligands.     

Solvothermal Syntheses and Magnetic Properties of Two New Coordination Polymers with Mixed Ligands

Two new coordination polymers, [Ni(H₂O)(BDC)(bpp)]_n ( 1 ) and [Co(mBDC)(bpp)]_n ( 2 ) (BDC = 1,4‐benzene dicarboxylate anion; bpp = 4,4′‐trimethylene dipyridine; mBDC = 1,3‐benzene dicarboxylate anion), were synthesized by solvothermal reaction and structurally characterized. Single crystal X‐ray diffraction showed that 1 consists of an inclined interpenetration of 1D nets generating an overall 3D entanglement and compound 2 of 1D chains. The luminescent and magnetic properties of both compounds in the solid state were also investigated. Crystal data: 1 : orthorhombic, Pnna; a = 18.3648(6), b = 13.6854(4), c = 16.2307(5) Å, V = 4079.3(2) ų, and Z = 8. Crystal data: 2 : triclinic, ; a = 8.6966(4), b = 10.1093(4), c = 11.8334(4) Å, α = 68.263(1)°, β = 82.895(1)°, γ = 78.370(1)°, V = 945.16(7) ų, and Z = 2.     

Structural Studies of a Copper(II) Complex with Inequivalent 2‐Acetylpyridine 3‐Piperidylthiosemicarbazonato Ligands and a Nickel(II) Complex with Different Modes of Coordination by the Two Thiosemicarbazonato Moieties of 1‐Phenylglyoxal Bis{N(4)‐diethylthiosemicarbazone}

The crystal structure of a copper(II) complex of 2‐acetylpyridine 3‐piperidylthiosemicarbazone, [Cu(Acpip)₂], indicates a tridentate, monoanionic ligand (i. e., pyridine nitrogen, imine nitrogen and thiolato sulfur atoms) and a bidentate, monanionic ligand (i. e., imine nitrogen and thiolato sulfur atoms). The stereochemistry approaches square pyramidal with the bidentate ligand occupying an apical (imine nitrogen atom) and basal (thiolato sulfur atom) position. The structure of a nickel(II) complex of 1‐phenylglyoxal N(4)‐diethylthiosemicarbazone, [Ni(Pg4DE)], has a 4‐6‐5 trichelate system rather than the 5‐5‐5 system common to bis(thiosemicarbazones). Coordination of the hydrazinic nitrogen atom of the “phenyl arm” along with the thiolato sulfur atom provides the 4‐membered chelate ring.     

Facial Coordination Chemistry in Nickel(II) Compounds with Linear Tridentate Ligands: Synthesis,Spectra and Redox Behavior

1:1 and 1:2 nickel(II) complexes of bis(benzimidazole-2-ylmethyl)amine (bbma) bis(benzimidazole-2-ylmethyl)sulfide (bbms), bis(benzimidazole-2-ylethyl)sulfide (bbes) and diethylenetriamine (dien) were prepared and their spectroscopic and redox behavior studied. The stereochemistry of nickel(II) complexes with bbma, bbes, bbms and dien have been analyzed, confirming facial configuration for Ni(bbma)²⁺ ₂ Cu(bbma)²⁺ ₂ and meridional geometry for Ni(dien)²⁺ ₂ and Cu(dien)²⁺ ₂. The factors favoring facial or meridional coordination of these ligands have been studied. For example, the π-bonding ability of benzimidazole at the termini of the tridentate ligand facilitate the facial geometry for the complexes, and the strong σ-donor ability of amine at the termini of the dien ligand favors meridionally coordinated complexes. The electronic spectral results indicate that the ligand field strength of the complexes decreases in the following order: Ni(bbms)²⁺ > Ni(bbes)²⁺ > Ni(bbma)²⁺ > Ni(dien)²⁺, this decreasing order being consistent with the redox potential obtained for these complexes.     

Synthesis,Characterization, and Thermostability of Four Novel Cadmium(II) Coordination Polymers with Mixed Ligands

Four novel mixed‐ligand complexes were obtained from the reaction of maleic acid, diimine chelating ligands and Cd(OH)₂ or CdO in a mixed solvent of water and methanol. The complexes were characterized by IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. The results show that all the four complexes are coordination polymers. [Cd(phen)(H₂O)(male)]_n · 2nH₂O ( 1 ) and [Cd(bipy)(H₂O)(male)]_n · 2nH₂O ( 2 ) (male = maleate; phen = 1, 10‐phenanthroline, bipy = 2, 2′‐bipyridine) are isomorphic, and the asymmetric unit is constructed by one Cd^II atom, a maleate group, a diimine ligand and two crystal water molecules. Each maleate group links two Cd^II atoms in a bis(bidentate) chelating mode, resulting in a 1D helical chain. Within [Cd(phen)(H₂O)₂(male)]_n · 2nH₂O ( 3 ), the maleate group bridges two Cd^II atoms in a bis(monodentate) chelating mode into a 1D helical chain along the [100] direction. The helical chain is decorated by phen groups alternatively at the two sides, and each phen plane of one chain is inserted in the void space between two adjacent phen ligands from an adjacent chain, resulting in a double zipper‐like chain. The asymmetric unit of [Cd₂(phen)₂(male)₂]_n ( 4 ) contains a Cd^II cation, one phen molecule, and a maleate group, and one bridging maleate group links three Cd^II atoms resulting in a 2D layer extending in [011] plane. The 2D networks are constructed by four kinds of rings formed by the central metal atom and maleate dianion. The thermostabilities of the four complexes were investigated.     

Synthesis,Characterization and Crystal Structures of Four Dinuclear Schiff Base Nickel(II) and Copper(II) Complexes with Versatile Bridging Groups

Four novel Schiff base nickel(II) and copper(II) complexes, derived from the end‐on (μ_1,1‐N₃) azide, end‐to‐end (μ_1,3‐NCS) thiocyanate, or phenolate oxygen bridges, have been synthesized and their crystal structures determined by X‐ray diffraction methods. They are the dinuclear double end‐on azide‐bridged [Ni₂(L1)₂(MeCN)₂(μ_1,1‐N₃)₂]·MeOH ( 1 ), the dinuclear double end‐on azide‐bridged [Ni₂(L2)₂(MeOH)₂(μ_1,1‐N₃)₂][Ni₂(L2)₂(OH₂)₂(μ_1,1‐N₃)₂]·MeOH ( 2 ), the dinuclear double end‐to‐end thiocyanate‐bridged [Cu₂(L3)₂(μ_1,3‐NCS)₂] ( 3 ), and the dinuclear double phenolate O‐bridged [Cu₂(L4)₂(NCS)₂] ( 4 ), where HL1, HL2, HL3 and HL4 are four tridentate Schiff bases obtained by the condensation of 3,5‐dibromosalicylaldehyde with N‐ethylethane‐1,2‐diamine, of 3,5‐dichlorosalicylaldehyde with N‐methylpropane‐1,3‐diamine, of 3‐bromo‐5‐chlorosalicylaldehyde with 2‐aminomethylpyridine, and of 5‐nitrosalicylaldehyde with 2‐aminomethylpyridine, respectively. Each nickel(II) atom in 1 and 2 is in an octahedral coordination, while each copper(II) atom in 3 and 4 is in a square pyramidal coordination. There exists crystallographic inversion centre symmetry in each of the complexes.     

pH‐Dependent Self‐Assembly of Complexes with Tripodal Amino Acid Ligand

Three new metal complexes were synthesized by reactions of [bis(2‐amino‐ethyl)‐amino]‐acetic acid (HL) and different metal salts at different pH values. Their structures were characterized by X‐ray crystallography. Interestingly, under acidic conditions, the dinuclear structure {Cu₂[H(L)]₂Cl₂}(ClO₄)₂ ( 1 ) was obtained, whereas under alkaline conditions, the complexes {[Cu(L)](ClO₄)}_n ( 2 ) and [Cd(L)Cl]_n ( 3 ), which exhibit distinct one‐dimensional (1D) structures, were obtained. The results indicate that the pH value, metal ions, and anions have remarkable influence on the formation and structure of the complexes.     

Structural Variability and Gas Adsorption Properties of Coordination Polymers Constructed with Aromatic Multicarboxylic and Bidentate Ligands

The self‐assembly reactions of transition metal ions and 1,3,5‐benzenetricarboxylic acid (H₃btc) in the presence of auxiliary aromatic bidentate ligands 1,10‐phenanthroline (1,10‐phen) or 4,4′‐bipyridine‐N,N′‐dioxide (4,4′‐bpdo) have isolated four coordination polymers [Co₁₈(btc)₁₀(H₂O)₆(OH)₆(1,10‐phen)₆] · 14H₂O · 3DMF ( 1 ) and [M₃(btc)₂(H₂O)₄(4,4′‐bpdo)] · 2H₂O · 2DMF [M = Co ( 2 ), Mn ( 3 ), Ni ( 4 )]. Single‐crystal X‐ray diffraction analysis revealed that the M₃ clusters in the structure of 1 – 4 are connected by hydroxyl group oxygen atoms (or oxygen atoms from 4,4′‐bpdo ligands) and carboxyl groups to generate a three‐dimensional framework. The network of final assemblies can be adjusted by varying the type of auxiliary ligands (1,10‐phen, 4,4′‐bpdo). In addition, the gas adsorption properties of 2 are also investigated.     

Self-Assembly of ZnII/CdII/PbII Coordination Polymers with a Tripodal Ligand Derived from Aromatase Inhibitor Letrozole Derivative

Reactions of the aromatase inhibitor letrozole derivative 4,4'-(1H-1,2,4-triazol-1-yl)methylene-bis(benzonic acid) (H₂tzmb) with Zn^II, Cd^II, or Pb^II salts under similar conditions resulted in the generation of three coordination polymers, namely, {[Zn(tzmb)(H₂tzmb)] · H₂O}_n ( 1 ), [Cd(tzmb)(H₂O)₂]_n ( 2 ), and {[Pb(tzmb)(H₂O)] · DMF}_n ( 3 ), respectively. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction, and thermogravimetric analyses. Complex 1 features a twofold 2D → 2D interpenetrated network based on corrugated 6³- hcb layers, and complex 2 exhibits a flat 2D 4.8²- fes network, whereas complex 3 presents a 3D hex net based on infinite rod-shaped secondary building units. The remarkable structural diversity may illustrate the powerful effect of metal ions on coordination assemblies. The spectroscopic, thermal, and photoluminescent properties of complexes 1 – 3 were investigated. In addition, the catalytic activity of 1 in the solvent-free ring-opening polymerization of ε-caprolactone was also discussed.     

两个双核铁（Ⅲ）和三足配体的配合物的合成和晶体结构

运用三足四齿配体三（2－甲基吡啶）胺（TPA）或三（2－甲基苯丙咪唑）胺（TBA）,得到两个双核铁(III)配合物，[Fe₂L₂(μ₂-O)(μ₂-p-NH₂-C₆H₄COO)]³⁺ (L = TPA, 1 和 L = TBA, 2)。两个配合物均为单斜晶系，空间群为P2(1)/c.晶胞参数 1: a = 1.4529(4), b = 1.6622(5), c = 2.0625(6) nm, β= 100.327(5)º, V = 4.900(3) nm³, z = 4, F(000) = 2344, 分子量M_r = 1142.91, Dc = 1.549 g/cm³, R₁ = 0.0544, R₂ = 0.0962. 2: a = 1.3378(4), b = 2.1174(7), c = 2.4351(7) nm, β= 97.315(6)º, V = 6.842(4) nm³, z = 4, F (000) = 3116, 分子量M_r = 1505.08, Dc = 1.444 g/cm³, R₁ = 0.0793, R₂ = 0.1623. 在两个双核铁(III)配合物中，中心的三价铁和配体TPA或TBA上的四个氮原子和两个氧原子通过不同的桥形成一个畸变的八面体构型。     

Three New Coordination Compounds with Neodymium Based on Tetrazole Containing Carboxylic Acid Ligands

Reactions of three tetrazole containing carboxylic acid ligands, namely, Hpztza, Htzpya, and Hpytza [Hpztza = 5‐(2‐pyrazinyl)tetrazole‐2‐acetic acid, Htzpya = 3‐(5‐tetrazolyl)pyridine‐1‐acetic acid, Hpytza = 5‐(3‐pyridyl)tetrazole‐2‐acetic acid] with NdCl₃ · 6H₂O under hydrothermal conditions, afforded the complexes [Nd(pztza)₂(H₂O)₆] · pztza · 3H₂O ( 1 ), [Nd₂(tzpya)₂(H₂O)₁₂]Cl₄ · 2H₂O ( 2 ), and [Nd(pytza)₂Cl(H₂O)₂] ( 3 ). The compounds were structurally characterized by elemental analysis, IR spectroscopy and single‐crystal X‐ray diffraction. X‐ray diffraction analyses revealed that compound 1 displays a mononuclear structure, 2 shows a dinuclear structure, and 3 features a 1D polymeric chain structure via pytza as linker. Furthermore, the luminescent properties investigated at room temperature in the solid state show that compound 2 has an obvious decrease in its luminescence, when compared to the ligand.     

Diverse Coordination Geometries Derived from Trisaminocyclohexane Ligands with Appended Outer-Sphere Hydrogen Bond Donors

With the aim of constructing hydrogen-bonding networks in synthetic complexes, two new ligands derived from cis,cis-1,3,5-triaminocyclohexane (TACH) have been prepared that feature pendant pyrrole or indole rings as outer-sphere H-bond donors. The TACH framework offers a facial arrangement of three N-donors, thereby mimicking common coordination motifs in the active sites of nonheme Fe and Cu enzymes. X-ray structural characterization of a series of Cu^I-X complexes (X=F, Cl, Br, NCS) revealed that these neutral ligands (H₃L^R, R=pyrrole or indole) coordinate in the intended facial N₃ manner, yielding four-coordinate complexes with idealized C₃ symmetry. The N−H units of the outer-sphere heterocycles form a hydrogen-bonding cavity around the axial (pseudo)halide ligand, as verified by crystallographic, spectroscopic, and computational analyses. Treatment of H₃L^pyrrole and H₃L^indole with divalent transition metal chlorides (M^IICl₂, M=Fe, Cu, Zn) causes one heterocycle to deprotonate and coordinate to the M(II) center, giving rise to tetradentate ligands with two remaining outer-sphere H-bond donors. Further ligand deprotonation is observed upon reaction with Ni(II) and Cu(II) salts with weakly coordinating counteranions. The reported complexes highlight the versatility of TACH-based ligands with pendant H-bond donors, as the resulting scaffolds can support multiple protonation states, coordination geometries, and H-bonding interactions.