Intermolecular dihydrogen- and hydrogen-bonding interactions in diammonium closo-decahydrodecaborate sesquihydrate.

The asymmetric unit of the title salt, 2NH(4)(+).B(10)H(10)(2-).1.5H(2)O or (NH(4))(2)B(10)H(10).1.5H(2)O, (I), contains two B(10)H(10)(2-) anions, four NH(4)(+) cations and three water molecules. (I) was converted to the anhydrous compound (NH(4))(2)B(10)H(10), (II), by heating to 343 K and its X-ray powder pattern was obtained. The extended structure of (I) shows two types of hydrogen-bonding interactions (N-H...O and O-H...O) and two types of dihydrogen-bonding interactions (N-H...H-B and O-H...H-B). The N-H...H-B dihydrogen bonding forms a two-dimensional sheet structure, and hydrogen bonding (N-H...O and O-H...O) and O-H...H-B dihydrogen bonding link the respective sheets to form a three-dimensional polymeric network structure. Compound (II) has been shown to form a polymer with the accompanying loss of H(2) at a faster rate than (NH(4))(2)B(12)H(12) and we believe that this is due to the stronger dihydrogen-bonding interactions shown in the hydrate (I).

Synthesis and characterization of homopolymers and copolymers containing closo-[B(12)H(12)](2-) boron cage derivatives.

Chains of cages: Neutral/ionic [B(12)H(12)](2-) boron-cage-functionalized methacrylate and styrene homopolymers or copolymers (see picture) are non-crystalline solids, T(g) increases as the number of B(12) cages in the chain of polystyrene increases, and homopolymers retain more weight than the copolymers when heated to 400 degrees C.New [B(12)H(12)](2-) boron cage functionalized neutral and ionic methacrylate and styrene monomers (1, 2, 3) were synthesized and these monomers were used to prepare homopolymers (4, 5, 6) and copolymers with methylmethacrylate (MMA) (7, 8), 2-hydroxyethylmethacrylate (HEMA) (11, 12, 13, 17), 2-hydroxyethylacrylate (HEA) (14, 15, 18), acrylamide (AA) (16), and styrene (9, 10, 19) with different monomer ratios. Free-radical initiated bulk and solution polymerization methods were used to synthesize these polymers and they were characterized by (1)H NMR, (11)B NMR, and IR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). Generally, the polymers show broad (1)H NMR and (11)B NMR peaks compared to their respective monomers. The copolymers have high molecular weights with higher [B(12)H(12)](2-) boron cage mole ratios. All the polymers on which DSC experiments were conducted (4 b, 5 b, 6 b, 7, 8, 9, 10, 17, 18, and 19) are non-glassy amorphous solids, except styrene copolymers (9, 19) and homopolymer (6 b) which show T(g) values of 100, 117, and 162 degrees C, respectively. Copolymers 9 and 10 have higher thermal stability (320 degrees C) than polymers 5 b, 4 b, and 8, which are stable up to 244, 250, and 260 degrees C, respectively. The homopolymers retained more weight than the copolymers when they were heated to 400 degrees C.

2-[2-(2-Pyrid-yl)eth-yl]isoindolinium perchlorate.

In the title salt, C(15)H(17)N(2) (+)·ClO(4) (-), the isoindoline N atom is protonated and an intra-molecular N-H⋯N hydrogen bond occurs. In the crystal, N-H⋯O and numerous weak C-H⋯O inter-actions occur between the cation and anion. The O atoms of the perchlorate anion are disordered over four sets of sites with occupancies of 0.438 (4), 0.270 (9), 0.155 (8) and 0.138 (5).

Di-µ-bromido-bis-({bis-[2-(2-pyrid-yl)eth-yl]amine}copper(II)) bis-(perchlorate).

Each Cu atom in the dinuclear centrosymmetric title complex, [Cu(2)Br(2)(C(14)H(17)N(3))(2)](ClO(4))(2), is ligated in a distorted square-pyramidal geometry (τ = 0.31) by a tridentate bis-[2-(2-pyrid-yl)eth-yl]amine ligand, and by two bridging Br atoms. In addition, the dinuclear species is stabilized by two hydrogen-bonded perchlorate anions.

(m-Phenyl-enedimethyl-ene)diammonium p-nitro-phenyl-phosphate perchlorate.

The title compound, C(8)H(14)N(2) (2+)·C(12)H(8)N(2)O(8)P(-)·ClO(4) (-), was formed by the reaction of α,α-bis-m-xylenediamine and sodium bis-p-nitro-phenyl-phosphate in the presence of Zn(ClO(4))·6H(2)O in methanol solution. The two amine groups of the m-xylenediammonium ion are each protonated and each hydrogen-bonded to two O atoms of the phosphate anion, which acts as a 1,3-bridge. The ammonium groups are arranged matched face to face and each pair is doubly bridged by two perchlorate ions through hydrogen bonding. In addition, there are also weak C-H⋯O inter-actions. Both the N-H⋯O and C-H⋯O inter-actions are contained in a channel down the a axis. The perchlorate oxygen atoms are disordered over two positions with site occupancy factors of ca 0.7 and 0.3.

(Acetonitrile)[bis-(2-pyridylmeth-yl)amine]bis-(perchlorato)copper(II).

In the title compound, [Cu(ClO(4))(2)(C(12)H(13)N(3))(C(2)H(3)N)], the Cu(II) atom is six-coordinate in a Jahn-Teller distorted octahedral geometry, with coordination by the tridentate chelating ligand, an acetonitrile mol-ecule, and two axial perchlorate anions. The tridentate ligand bis-(2-pyridylmeth-yl)amine chelates meridionally and equatorially while an acetonitrile mol-ecule is coordinated at the fourth equatorial site. The two perchlorate anions are disordered with site occupancy factors of 0.72/0.28. The amine H is involved in intra-molecular hydrogen bonding to the perchlorate O atoms and there are extensive but weak inter-molecular C-H⋯O inter-actions.

[(6-Methyl-2-pyridylmeth-yl)(2-pyridylmeth-yl)amine][(2-pyridylmeth-yl)amine]copper(II) bis-(perchlorate).

The title compound, [Cu(C(6)H(8)N(2))(C(13)H(15)N(3))](ClO(4))(2), is a mixed ligand complex with the Cu(II) atom coordinated by (6-methyl-2-pyridylmeth-yl)(2-pyridylmeth-yl)amine, acting as a tridentate ligand, and 2-(2-amino-meth-yl)pyridine, as a bidentate ligand, leading to an N(5) square-pyramidal geometry. The amine H atoms are involved in hydrogen bonding to the perchlorate O atoms and there are extensive but weak inter-molecular C-H⋯O inter-actions in the crystal structure. The perchlorate ions are each disordered over two positions, with site occupancies of 0.601 (8):0.399 (8) and 0.659 (11):0.341 (11).

Studies of a dinuclear manganese complex with phenoxo and bis-acetato bridging in the Mn2(II,II) and Mn2(II,III) states: Coordination structural shifts and oxidation state control in bridged dinuclear complexes.

The dinucleating ligand, 2,6-bis{[(2-(2-pyridyl)ethyl)(2-pyridylmethyl)-amino]-methyl}-4-methylphenol) (L1OH) reacts with Mn(ClO4)2.6H2O to form the dinuclear complex [Mn2(II,II)(L1O)(mu-OOCCH3)2]ClO4 (1). The electrolytic oxidation of 1 at 0.7 V (vs Ag/AgCl) produces the mixed valent complex [Mn2(II,III)(L1O)(mu-OOCCH3)2](ClO4)2 (1ox) quantitatively, while electrolysis at 0.20 V converts 1ox back to 1. X-ray crystallographic structures show that both 1 and 1ox are dinuclear complexes in which the two manganese ions are each in distorted octahedral coordination environments bridged by the phenoxo oxygen and two acetate ions. The structural changes that occur upon the oxidation 1 to 1ox suggest an extended pi-bonding system involving the phenoxo ring C-O(phenoxo)-Mn(II)-N(pyridyl) chain. In addition, as 1 is oxidized to 1ox, the rearrangements in the coordination sphere resulting from the oxidation of one Mn(II) ion to Mn(III) are transmitted via the bridging Mn-O(phenoxo) bonds and cause structural changes that render the site of the second manganese ion unfit for the +3 state and hence unstable to reduction. Thus the electrolytic oxidation of 1ox in acetonitrile at 1.20 V takes up slightly greater than 1 F of charge/mol of 1ox, but the starting complex, 1ox, is recovered, showing the instability of the Mn2(III,III) state that is formed with respect to reduction to 1ox. Variable-temperature magnetic susceptibility measurements of 1 and 1ox over the temperature range from 1.8 to 300 K can be modeled with magnetic coupling constants J = -4.3 and -4.1 cm(-1), respectively showing the weak antiferromagnetic coupling between the two manganese ions in each dinuclear complex, which is commonly observed among similar phenoxo- and bis-1,3-carboxylato-bridged dinuclear Mn2(II,II) and Mn2(II,III) complexes.

Dioxo-bridged dinuclear manganese(III) and -(IV) complexes of pyridyl donor tripod ligands: combined effects of steric substitution and chelate ring size variations on structural, spectroscopic, and electrochemical properties.

The syntheses and structural, spectral, and electrochemical characterization of the dioxo-bridged dinuclear Mn(III) complexes [LMn(mo-O)(2)MnL](ClO(4))(2), of the tripodal ligands tris(6-methyl-2-pyridylmethyl)amine (L(1)) and bis(6-methyl-2-pyridylmethyl)(2-(2-pyridyl)ethyl)amine (L(2)), and the Mn(II) complex of bis(2-(2-pyridyl)ethyl)(6-methyl-2-pyridylmethyl)amine (L(3)) are described. Addition of aqueous H(2)O(2) to methanol solutions of the Mn(II) complexes of L(1) and L(2) produced green solutions in a fast reaction from which subsequently precipitated brown solids of the dioxo-bridged dinuclear complexes 1 and 2, respectively, which have the general formula [LMn(III)(mu-O)(2)Mn(III)L](ClO(4))(2). Addition of 30% aqueous H(2)O(2) to the methanol solution of the Mn(II) complex of L(3) ([Mn(II)L(3)(CH(3)CN)(H(2)O)](ClO(4))(2) (3)) showed a very sluggish change gradually precipitating an insoluble black gummy solid, but no dioxo-bridged manganese complex is produced. By contrast, the Mn(II) complex of the ligand bis(2-(2-pyridyl)ethyl)(2-pyridylmethyl)amine (L(3a)) has been reported to react with aqueous H(2)O(2) to form the dioxo-bridged Mn(III)Mn(IV) complex. In cyclic voltammetric experiments in acetonitrile solution, complex 1 shows two reversible peaks at E(1/2) = 0.87 and 1.70 V (vs Ag/AgCl) assigned to the Mn(III)(2) <--> Mn(III)Mn(IV) and the Mn(III)Mn(IV) <--> Mn(IV)(2) processes, respectively. Complex 2 also shows two reversible peaks, one at E(1/2) = 0.78 V and a second peak at E(1/2) = 1.58 V (vs Ag/AgCl) assigned to the Mn(III)(2) <--> Mn(III)Mn(IV) and Mn(III)Mn(IV) <--> Mn(IV)(2) redox processes, respectively. These potentials are the highest so far observed for the dioxo-bridged dinuclear manganese complexes of the type of tripodal ligands used here. The bulk electrolytic oxidation of complexes 1 and 2, at a controlled anodic potential of 1.98 V (vs Ag/AgCl), produced the green Mn(IV)(2) complexes that have been spectrally characterized. The Mn(II) complex of L(3) shows a quasi reversible peak at an anodic potential of E(p,a) of 1.96 V (vs Ag/AgCl) assigned to the oxidation Mn(II) to Mn(III) complex. It is about 0.17 V higher than the E(p,a) of the Mn(II) complex of L(3a). The higher oxidation potential is attributable to the steric effect of the methyl substituent at the 6-position of the pyridyl donor of L(3).