Robert P. Houser

Structural variation in copper(I) complexes with pyridylmethylamide ligands: structural analysis with a new four-coordinate geometry index, τ4

Four Cu(I) complexes were synthesized with a family of pyridylmethylamide ligands, HL(R) [HL(R) = N-(2-pyridylmethyl)acetamide, R = null; 2,2-dimethyl-N-(2-pyridylmethyl)propionamide, R = Me(3); 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide, R = Ph(3))]. Complexes 1-3 were synthesized from the respective ligand and [Cu(CH(3)CN)(4)]PF(6) in a 2 : 1 molar ratio: [Cu(HL)(2)]PF(6) (1), [Cu(2)(HL(Me3))(4)](PF(6))(2) (2), [Cu(HL(Ph3))(2)]PF(6) (3). Complex 4, [Cu(HL)(CH(3)CN)(PPh(3))]PF(6), was synthesized from the reaction of HL with [Cu(CH(3)CN)(4)]PF(6) and PPh(3) in a 1 : 1 : 1 molar ratio. X-Ray crystal structures reveal that complexes 1, 3 and 4 are mononuclear Cu(I) species, while complex 2 is a Cu(I) dimer. The copper ions are four-coordinate with geometries ranging from distorted tetrahedral to seesaw in 1, 2, and 4. Complexes 1 and 2 are very air sensitive and they display similar electrochemical properties. The coordination geometry of complex 3 is nearly linear, two-coordinate. Complex 3 is exceptionally stable with respect to oxidation in the air, and its cyclic voltammetry shows no oxidation wave in the range of 0-1.5 V. The unusual inertness of complex 3 towards oxidation is attributed to the protection from bulky triphenyl substituent of the HL(Ph3) ligand. A new geometric parameter for four-coordinate compounds, tau(4), is proposed as an improved, simple metric for quantitatively evaluating the geometry of four-coordinate complexes and compounds.

Nickel(II) and manganese(II) 1D chain coordination polymers with 1,2,4,5-benzenetetracarboxylato anions

Abstract Five new coordination complexes were synthesized under ambient conditions in water, or water/ethanol by combining a Mn2+ or Ni2+ salt with BTEC and an imidazole derivative forming [Mn(Him)4(H2O)2][Mn(BTEC)(Him)2(H2O)2]·4H2O (1), [Ni(Him)4(H2O)2][Ni(BTEC)(Him)2(H2O)2]·4H2O (2), [2-MeH2im]2[Mn(BTEC)(H2O)4]·5H2O (3), [Mn(4-MeHim)6][Mn(BTEC)(H2O)4]·H2O (4), and [Mn2(BTEC)(HBzim)4(H2O)6]·2H2O (5) (BTEC=1,2,4,5-benzenetetracarboxylate; Him=imidazole; 2-MeH2im=2-methylimidazolium; 4-MeHim=4-methylimidazole; HBzim=benzimidazole). Complexes 1–5 were characterized by TGA, FT-IR, elemental analysis and X-ray crystallography. Complexes 1–5 all crystallize in the triclinic space group P1. Complexes 1–4 are coordination polymers, possessing 1D linear chain structures, while complex 5 is a discrete bimetallic complex. The anionic linear 1D chains in 1–4 are comprised of BTEC ligands that bridge between metal atoms. The cations are either metal complexes (1, 2 and 4) or protonated 2-MeHim (3), which has a lower pKb.

Synthesis and Characterization of Polynuclear Copper(II) Complexes with Pyridylbis(phenol) Ligands

Three new pyridylbis(phenol) ligands with imine (H(2)L(imine)), amine (H(2)L(amine)), or amide (H(4)L(amide)) linkages, along with their copper complexes, were synthesized and characterized. Treatment of H(2)L(imine) with copper(II) in the presence of base produced mononuclear copper complex [Cu(L(imine))(MeOH)] (1), while the same procedure with H(2)L(amine) produced trinuclear [Cu(3)(L(amine))(2)(CH(3)CN)(2)](ClO(4))(2) (2). The more rigid H(4)L(amide) forms tetranuclear [Cu(4)(L(amide))(2)(H(2)O)(4)] (3), which upon recrystallization yielded crystals of hexanuclear [Cu(6)(HL(amide))(4)(H(2)O)(2)] (4).

Copper(I) and copper(II) complexes with pyrazine-containing pyridylalkylamide ligands N -(pyridin-2-ylmethyl)pyrazine-2-carboxamide and N -(2-(pyridin-2-yl)ethyl)pyrazine-2-carboxamide

Four copper(II) complexes and one copper(I) complex with pyridine-containing pyridylalkylamide ligands N-(pyridin-2-ylmethyl)pyrazine-2-carboxamide (HLpz) and N-(2-(pyridin-2-yl)ethyl)pyrazine-2-carboxamide (HLpzʹ) were synthesized and characterized. The X-ray crystal structures of [Cu2(Lpz)2(4,4ʹ-bipy)(OTf)2] (1, OTf = trifluoromethanesulfonate, 4,4ʹ-bipy = 4,4ʹ-bipyridine) and [Cu(Lpz)(py)2]OTf·H2O (2, py = pyridine) revealed binuclear and mononuclear molecular species, respectively, while [Cu(Lpz)(μ2-1,1-N3)]n (3), [Cu(Lpzʹ)(μ2-1,3-N3)]n (4), and [Cu(HLpz)Cl]n (5) are coordination polymer 1-D chains in the solid state.

Multinuclear copper complexes of pyridylmethylamide ligands.

Copper complexes of a family of pyridylmethylamide ligands HL(Ph), HL(Me3) and HL(Ph3) were synthesized and characterized [HL(Ph) = 2-phenyl-N-(2-pyridylmethyl)acetamide; HL(Me3) = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HL(Ph3) = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide]. The reaction of copper(II) salts with the HL family and triethylamine in methanol yields copper(II) complexes [Cu4(L(Ph))4(OH)2](ClO4)2 (1), [Cu2(HL(Me3))2(OMe)2(MeOH)2](OTf)2 (2) and [Cu2(HL(Ph3))2(OMe)2(MeOH)2](OTf)2 (3). The complexes have different nuclearity owing to varying steric properties of the ligands used. Complex 1 self-assembles in the presence of excess base to form a tetranuclear complex. Complexes 2 and 3 are binuclear and are bridged by a pair of methoxide ligands. Steric encumbrance of the ligands in 2 and 3 prevent cluster formation.

2,2,2‐Triphenyl‐N‐(2‐pyridylmeth­yl)acetamide

The title compound, C26H22N2O, possesses normal geometric parameters and forms centrosymmetric dimeric associations via N—H⋯N hydrogen bonds.

Copper(II) and cobalt(II) coordination polymers with bridging 1,2,4,5-benzenetetracarboxylate and N-methylimidazole: coordination number-determined sheet topology

Two new coordination polymers were synthesized under ambient conditions in water by combining a cobalt(II) or copper(II) metal salt with 1,2,4,5-benzenetetracarboxylate (BTEC) and N-methylimidazole (Meim), forming Co2(BTEC)(Meim)4(H2O)4·H2O (1) and Cu2(BTEC)(Meim)4 (2). Compounds 1 and 2 were characterized by X-ray crystallography, powder X-ray diffraction, TGA, FT-IR and elemental analysis. The crystal structures and 2D polymeric structures of compounds 1 and 2 are reported. Coordination polymer 1 crystallizes in the monoclinic space group C2/c. Coordination polymer 2 crystallizes in the triclinic space group P. Both 1 and 2 are made up of infinite sheets of BTEC ligands and metal ions. The sheets in 1 are puckered, giving an offset zigzag sheet topology, while the sheets in 2 are flat. Significant π–π stacking between Meim rings on adjacent sheets contributes to inter-sheet interactions in both 1 and 2. While hydrogen bonding does not play a role in 2, significant hydrogen bonding between sheets in 1 also stabilizes inter-sheet interactions.

2-Methyl-N,N′-bis­[2-(methyl­sulfan­yl)eth­yl]-2-(2-pyrid­yl)-N,N′-ditosyl­propane-1,3-diamine

The crystal structure of the title compound, C29H39N3O4S4, was determined at 97 K and possesses normal geometric parameters.

Bis{2-hydr-oxy-N-[2-(2-pyrid-yl)eth-yl]benzamide}copper(I) tetra-fluoridoborate.

The title complex, [Cu(C14H14N2O2)2]BF4, is a monomeric copper(I) species with linear two-coordinate geometry around the CuI atom. The asymmetric unit contains two half-cations that sit on crystallographic twofold rotation axes. The selected crystal was non-merohedrally twinned by a twofold rotation about an axis normal to the (100) family of planes. The ratio of the twin components refined to 0.4123 (6). Two 2-hydroxy-N-[2-(2-pyridyl)ethyl]benzamide ligands coordinate to each CuI atom via the pyridyl N atom. Intramolecular hydrogen bonding between the phenol OH groups and the amide O atoms imparts rigidity and planarity to the non-coordinating end of the ligand. The cationic complex is linked to the BF4 − anions via hydrogen bonding between the amide NH groups in the cations and BF4 − anions.