Syntheses and Structures of Mononuclear, Dinuclear and Polynuclear Silver(I) Complexes of 2‑Pyrazole-Substituted 1,10-Phenanthroline Ligands

A series of mononuclear, dinuclear and polynuclear silver­(I) complexes (<b>1</b>–<b>6</b>) bearing 2-pyrazole-substituted 1,10-phenanthroline derivatives (<b>L</b>^<b>1</b>, ^<b>F</b><b>L</b>^<b>1</b>, <b>L</b>^<b>2</b>) have been synthesized and characterized by ¹H and ¹³C NMR, IR spectroscopy, elemental analysis, and single crystal X-ray diffraction. Reaction of <b>L</b>^<b>1</b> (<b>L</b>¹ = 2-(3,5-dimethylpyrazol-1-yl)-1,10-phenanthroline) with AgClO₄ or AgBF₄ afforded two dinuclear silver­(I) complexes [Ag₂(<b>L</b>^<b>1</b>)₂(CH₃CN)₂]­(ClO₄)₂ (<b>1</b>) and [Ag₂(<b>L</b>^<b>1</b>)₂(CH₃CN)₂]­(BF₄)₂ (<b>2</b>), in which two [Ag<b>L</b>^<b>1</b>(CH₃CN)]⁺ units are linked by Ag···Ag interaction (Ag···Ag separation: 3.208(2) and 3.248(1) Å, respectively). A one-dimensional polymer {[Ag<b>L</b>^<b>1</b>]­(BF₄)}_∞ (<b>3</b>) consisting of an infinite ···Ag···Ag···Ag··· chain (Ag···Ag separation: 3.059(1) Å), as well as a dinuclear complex [Ag₂(ClO₄)₂(<b>L</b>^<b>1</b>)₂] (<b>4</b>) in which the perchlorate anions instead of solvents are involved in the metal coordination, have also been obtained. The mononuclear complex [Ag­(^<b>F</b><b>L</b>^<b>1</b>)₂]­(BF₄) (<b>5</b>) was synthesized from ^<b>F</b><b>L</b>^<b>1</b> (^<b>F</b><b>L</b>^<b>1</b> = 2-(3,5-bis­(trifluoromethyl)­pyrazol-1-yl)-1,10-phenanthroline) and AgBF₄, while the dinuclear [Ag₂(BF₄)₂(<b>L</b>^<b>2</b>)₂] (<b>6</b>) was isolated from <b>L</b>^<b>2</b> (<b>L</b>^<b>2</b> = 2-[<i>N</i>-(3-methyl-5-phenylpyrazole)]-1,10-phenanthroline). The photoluminescence properties of the ligands and complexes <b>1</b>–<b>6</b> have been studied both in the solid state and in solution

Homometallic Silver(I) Complexes of a Heterotopic NHC-Bridged Bis-Bipyridine Ligand

By varying the metal to ligand ratio, stepwise formation of a series of homonuclear silver­(I) complexes of a carbene-bridged bis-bipyridine ligand (L) was achieved. In the mononuclear 1:2 complex [AgL₂]Br (<b>1</b>) only the carbene carbon is involved in the metal coordination, while both of the 2,2′-bipyridine (bpy) arms are free. When the amount of silver­(I) ion was increased, isomorphous 2:2 dinuclear complexes with different counteranions, [Ag₂L₂]­X₂ (X = Br^– (<b>2a</b>), PF₆^– (<b>2b</b>), BPh₄^– (<b>2c</b>)), were synthesized from the ligand LX, in which the carbene carbon and one of the bpy units participate in the coordination with silver­(I) ions. Further addition of Ag^I salt afforded the one-dimensional coordination polymer {[Ag₃L₂]­(PF₆)₃·4CH₃CN}_<i>n</i> (<b>3</b>), wherein the hanging bipyridine units also coordinate with Ag^I and thus all the coordination sites of the ligand are employed. The results reveal the preference of Ag^I ion for the carbene carbon donor rather than the bpy units. The synthesis, structures, and interconversion of the complexes and the counteranion effects on the structures are reported, and the luminescent properties of the ligand LX and the silver complexes have also been studied

Reactions of α-Diimine-Stabilized Zn–Zn-Bonded Compounds with Phenylacetylene

Treatment of the Zn–Zn-bonded compounds [L^2–Zn–ZnL^2–]·[M­(THF)₂]₂ (<b>1a</b>, M = Na; <b>1b</b>, M = K; L = [(2,6-<i>i</i>Pr₂C₆H₃)­NC­(Me)]₂), which contain doubly reduced α-diimine ligands, with 15-crown-5 and 18-crown-6 led to the ion-separated compounds [L^2–Zn–ZnL^2–]·[Na­(15-crown-5)­(THF)₂]₂ (<b>2a</b>), [L^2–Zn–ZnL^2–]·[K­(15-crown-5)₂]₂·4THF (<b>2b</b>), and [L^2–Zn–ZnL^2–]·[K­(18-crown-6)­(THF)₂]₂·2THF (<b>2c</b>). In the products, the alkali metal ions originally bound by the ligands have been captured by the crown ethers. The Zn–Zn bond distances in <b>2a</b>, <b>2b</b>, and <b>2c</b> are longer than those in the corresponding parent compounds <b>1a</b> and <b>1b</b> and in an analogous compound, [L^–Zn–ZnL^–] (<b>3</b>), bearing the monoanionic α-diimine ligands. Theoretical computations suggested that the Zn–Zn bonds in <b>2a</b>–<b>c</b> are less stable than those in <b>1a</b> and <b>1b</b>. Reactions of [L^–Zn–ZnL^–] (<b>3</b>) with different amounts of PhCCH afforded the dimeric product [L^–Zn­(μ-CCPh)]₂ (<b>4</b>) and the monomeric [L⁰Zn­(CCPh)₂]·2THF (<b>5</b>), respectively, while the reaction of the crown ether-containing compound <b>2b</b> with PhCCH gave a homoleptic zinc alkynide, [Zn­(CCPh)₄]·[K­(15-crown-5)₂]₂·THF (<b>6</b>)

Reactions of α-Diimine-Stabilized Zn–Zn-Bonded Compounds with Phenylacetylene

Treatment of the Zn–Zn-bonded compounds [L^2–Zn–ZnL^2–]·[M­(THF)₂]₂ (<b>1a</b>, M = Na; <b>1b</b>, M = K; L = [(2,6-<i>i</i>Pr₂C₆H₃)­NC­(Me)]₂), which contain doubly reduced α-diimine ligands, with 15-crown-5 and 18-crown-6 led to the ion-separated compounds [L^2–Zn–ZnL^2–]·[Na­(15-crown-5)­(THF)₂]₂ (<b>2a</b>), [L^2–Zn–ZnL^2–]·[K­(15-crown-5)₂]₂·4THF (<b>2b</b>), and [L^2–Zn–ZnL^2–]·[K­(18-crown-6)­(THF)₂]₂·2THF (<b>2c</b>). In the products, the alkali metal ions originally bound by the ligands have been captured by the crown ethers. The Zn–Zn bond distances in <b>2a</b>, <b>2b</b>, and <b>2c</b> are longer than those in the corresponding parent compounds <b>1a</b> and <b>1b</b> and in an analogous compound, [L^–Zn–ZnL^–] (<b>3</b>), bearing the monoanionic α-diimine ligands. Theoretical computations suggested that the Zn–Zn bonds in <b>2a</b>–<b>c</b> are less stable than those in <b>1a</b> and <b>1b</b>. Reactions of [L^–Zn–ZnL^–] (<b>3</b>) with different amounts of PhCCH afforded the dimeric product [L^–Zn­(μ-CCPh)]₂ (<b>4</b>) and the monomeric [L⁰Zn­(CCPh)₂]·2THF (<b>5</b>), respectively, while the reaction of the crown ether-containing compound <b>2b</b> with PhCCH gave a homoleptic zinc alkynide, [Zn­(CCPh)₄]·[K­(15-crown-5)₂]₂·THF (<b>6</b>)

Chloride Coordination by Oligoureas: From Mononuclear Crescents to Dinuclear Foldamers

A series of acyclic oligourea receptors which closely resemble the scaffolds and coordination behavior of oligopyridines have been synthesized. Assembly of the receptors with chloride ions afforded mononuclear anion complexes or dinuclear foldamers depending on the number of the urea groups

Alkali Metal and Zinc Complexes of a Bridging 2,5-Diamino-1,4-Benzoquinonediimine Ligand

Two alkali metal complexes of a bridging 2,5-diamino-1,4-benzoquinonediimine ligand (dipp-dabqdiH₂), [(thf)₂Li­(μ-dipp-dabqdi)­Li­(thf)₂] (<b>1</b>) and [(dme)_1.5Na­(μ-dipp-dabqdi)­Na­(dme)_1.5]_<i>n</i> (<b>2</b>, dme = 1,2-dimethoxyethane), have been synthesized by the reaction of dipp-dabqdiH₂ with Li^<i>n</i>Bu or sodium metal. In addition, treatment of 1,2,4,5-tetrakis­(2,6-diisopropylamino)­benzene (dipp-tabH₄) with potassium metal in dme afforded the complex [(dme)₂K­(μ-dipp-tabH₂)­K­(dme)₂] (<b>3</b>). X-ray crystal diffraction analyses revealed that complexes <b>1</b> and <b>3</b> have dinuclear structures, while the sodium complex <b>2</b> aggregates to a one-dimensional polymer through bridging dme ligands. With increasing ion radius, the coordination number of the alkali metal (Li, Na, and K) increases from four to five to six, while the coordination geometry changes from distorted tetrahedral to square pyramidal and further to octahedral in <b>1</b>, <b>2</b>, and <b>3</b>, respectively. The salt metathesis reactions of <b>1</b> and <b>2</b> with anhydrous ZnCl₂ yielded the ion-contacted zinc complexes [(thf)₃Li­(μ-Cl)­ClZn­(μ-dipp-dabqdi)­ZnCl­(μ-Cl)­Li­(thf)₃] (<b>4</b>), [(dme)₂Li­(μ-Cl)­ClZn­(μ-dippdabqdi)­ZnCl­(μ-Cl)­Li­(dme)₂] (<b>5</b>), and [(dme)₂Na­(μ-Cl)₂Zn­(μ-dipp-dabqdi)­Zn­(μ-Cl)₂Na­(dme)₂] (<b>6</b>), respectively. The ligand exists as the dianionic form in compounds <b>1</b>–<b>6</b> upon double deprotonation, and a complete electronic delocalization (except for <b>3</b>) of the quinonoid π-system is observed between the metal centers over the two NCCCN halves of the ligand. The electronic structures of the complexes were studied by density functional theory (DFT) computations

Chloride Encapsulation by a Tripodal Tris(4-pyridylurea) Ligand and Effects of Countercations on the Secondary Coordination Sphere

A series of anion complexes of the 4-pyridyl-functionalized tripodal tris­(urea) receptor (<b>L</b>) have been synthesized. Ligand <b>L</b> forms the 1:1 anion complex [Cl⊂<b>L</b>]⁻ with various metal chloride salts, MCl_<i>x</i> (M = Na, K, Mg, Ca, Mn, Co, <i>x</i> = 1 or 2). When M = Na, K, Mg, and Ca, the metal ions are not coordinated by the pyridyl groups of <b>L</b> but are involved in second-sphere coordination to form three-dimensional structures. However, in the complex of Co²⁺, the transition metal ions are directly coordinated by the pyridyl groups. Interestingly, the Mn²⁺ ion forms two complexes with both of the above two types of structure. In all complexes, one chloride ion is “half” encapsulated in the cleft of one ligand by N–H···Cl hydrogen bonds to form the [Cl⊂<b>L</b>] units, which are further linked via intermolecular interactions into three-dimensional structures. Moreover, the fluoride and carbonate complexes of <b>L</b> have also been obtained. The solution anion binding properties of <b>L</b> have been studied by ¹H NMR spectroscopy and electrospray ionization mass spectrometry

Multinuclear Alkali Metal Complexes of a Triphenylene-Based Hexamine and the Transmetalation to Tris(N-heterocyclic tetrylenes) (Ge, Sn, Pb)

A <i>C</i>₃-symmetric hexamine (<b>LH</b>_<b>6</b>) based on the triphenylene and <i>ortho</i>-phenylenediamine (PDAH₂) skeletons has been synthesized, and was partially or fully deprotonated upon treatment with alkali metal agents to afford amino–amido or diamido coordination sites. Four alkali metal complexes, the dinuclear [Na₂(<b>LH</b>_<b>4</b>)­(DME)₅] (<b>1</b>) and [K₂(<b>LH</b>_<b>4</b>)­(DME)₄] (<b>2</b>), trinuclear [K₃(<b>LH</b>_<b>3</b>)­(DME)₆] (<b>3</b>), and hexanuclear [Li₆(<b>L</b>)­(DME)₆] (<b>4</b>), were obtained and used in transmetalation/ligand exchange with other metals. The hexalithium salt of the fully deprotonated ligand, [Li₆<b>L</b>], reacted with heavier group 14 element halides to yield three tris­(N-heterocyclic tetrylenes), the germylene [Ge₃(<b>L</b>)] (<b>5</b>), stannylene [Sn₃(<b>L</b>)] (<b>6</b>), and plumbylene [Pb₃(<b>L</b>)] (<b>7</b>). The synthesis and crystal and electronic structures of these compounds are reported

Synthesis and Reactivity of Nickel Hydride Complexes of an α‑Diimine Ligand

Reaction of L⁰NiBr₂ with 2 equiv of NaH yielded the Ni^II hydride complex [(L^•–)­Ni­(μ-H)₂Ni­(L^•–)] (<b>1</b>) (L = [(2,6-<i>i</i>Pr₂C₆H₃)­NC­(Me)]₂; L⁰ represents the neutral ligand, L^•– is its radical-anionic form, and L^2– denotes the dianion) in good yield. Stepwise reduction of complex <b>1</b> led to a series of nickel hydrides. Reduction of <b>1</b> with 1 equiv of sodium metal afforded a singly reduced species [Na­(DME)₃]­[(L^•–)­Ni­(μ-H)₂Ni­(L^•–)] (<b>2a</b>) (DME = 1,2-dimethoxyethane), which contains a mixed-valent core [Ni­(μ-H)₂Ni]⁺. With 2 equiv of Na a doubly reduced species [Na­(DME)]₂[L^2–Ni­(μ-H)₂NiL^2–] (<b>3a</b>) was obtained, in which each monoanion (L^•–) in the precursor <b>1</b> has been reduced to L^2–. By using potassium as the reducing agent, two analogous species [K­(DME)₄]­[(L^•–)­Ni­(μ-H)₂Ni­(L^•–)] (<b>2b</b>) and [K­(DME)]₂[L^2–Ni­(μ-H)₂NiL^2–] (<b>3b</b>) were obtained. Further treatment of <b>3b</b> with 2 equiv of K led to a trinuclear complex [K­(DME)­(THF)]₂K₂[L^2–Ni­(μ-H)₂Ni­(μ-H)₂NiL^2–] (<b>4</b>), which contains one Ni^II and two Ni^I centers with a triplet ground state. When <b>1</b> and <b>3a</b> were warmed in toluene or benzene, respectively, three reverse-sandwich dinickel complexes, [(L^•–)­Ni­(μ-η³:η³-C₇H₈)­Ni­(L^•–)] (<b>5</b>) and [Na­(DME)]₂[L^2–Ni­(μ-η³:η³-C₆H₅R)­NiL^2–] (<b>6</b>: R = CH₃; <b>7</b>: R = H), were isolated. Reaction of <b>1</b> with Me₃SiN₃ gave the N₃-bridged complex [(L^•–)­Ni­(μ-η¹-N₃)₂Ni­(L^•–)] (<b>8</b>). The crystal structures of complexes <b>1</b>–<b>8</b> have been determined by X-ray diffraction, and their electronic structures have been fully studied by EPR/NMR spectroscopy

Synthesis and Reactivity of Nickel Hydride Complexes of an α‑Diimine Ligand

Reaction of L⁰NiBr₂ with 2 equiv of NaH yielded the Ni^II hydride complex [(L^•–)­Ni­(μ-H)₂Ni­(L^•–)] (<b>1</b>) (L = [(2,6-<i>i</i>Pr₂C₆H₃)­NC­(Me)]₂; L⁰ represents the neutral ligand, L^•– is its radical-anionic form, and L^2– denotes the dianion) in good yield. Stepwise reduction of complex <b>1</b> led to a series of nickel hydrides. Reduction of <b>1</b> with 1 equiv of sodium metal afforded a singly reduced species [Na­(DME)₃]­[(L^•–)­Ni­(μ-H)₂Ni­(L^•–)] (<b>2a</b>) (DME = 1,2-dimethoxyethane), which contains a mixed-valent core [Ni­(μ-H)₂Ni]⁺. With 2 equiv of Na a doubly reduced species [Na­(DME)]₂[L^2–Ni­(μ-H)₂NiL^2–] (<b>3a</b>) was obtained, in which each monoanion (L^•–) in the precursor <b>1</b> has been reduced to L^2–. By using potassium as the reducing agent, two analogous species [K­(DME)₄]­[(L^•–)­Ni­(μ-H)₂Ni­(L^•–)] (<b>2b</b>) and [K­(DME)]₂[L^2–Ni­(μ-H)₂NiL^2–] (<b>3b</b>) were obtained. Further treatment of <b>3b</b> with 2 equiv of K led to a trinuclear complex [K­(DME)­(THF)]₂K₂[L^2–Ni­(μ-H)₂Ni­(μ-H)₂NiL^2–] (<b>4</b>), which contains one Ni^II and two Ni^I centers with a triplet ground state. When <b>1</b> and <b>3a</b> were warmed in toluene or benzene, respectively, three reverse-sandwich dinickel complexes, [(L^•–)­Ni­(μ-η³:η³-C₇H₈)­Ni­(L^•–)] (<b>5</b>) and [Na­(DME)]₂[L^2–Ni­(μ-η³:η³-C₆H₅R)­NiL^2–] (<b>6</b>: R = CH₃; <b>7</b>: R = H), were isolated. Reaction of <b>1</b> with Me₃SiN₃ gave the N₃-bridged complex [(L^•–)­Ni­(μ-η¹-N₃)₂Ni­(L^•–)] (<b>8</b>). The crystal structures of complexes <b>1</b>–<b>8</b> have been determined by X-ray diffraction, and their electronic structures have been fully studied by EPR/NMR spectroscopy