Formation of Mono- and Multimanganese Cationic Species. Crystal Structure of [Mn₄(μ-Cl)₆(THF)₁₂][SnCl₅(THF)]₂

Formation of Mono- and Multimanganese Cationic Species. Crystal Structure of [Mn4(μ-Cl)6(THF)12][SnCl5(THF)]2</sub

Formation of Mono- and Multimanganese Cationic Species. Crystal Structure of [Mn₄(μ-Cl)₆(THF)₁₂][SnCl₅(THF)]₂

Formation of Mono- and Multimanganese Cationic Species. Crystal Structure of [Mn4(μ-Cl)6(THF)12][SnCl5(THF)]2</sub

¹H NMR Investigation of High-Spin and Low-Spin Iron(III) <b><i>meso</i></b>-Ethynylporphyrins

The 1H NMR spectra of iron(III) 5-ethynyl-10,15,20-tri(p-tolyl)porphyrin [(ETrTP)FeIIIXn], iron(III) 5-(phenylethynyl)-10,15,20-tri(p-tolyl)porphyrin [(PETrTP)FeIIIXn], iron(III) 5-(phenylbutadiynyl)-10,15,20-tri(p-tolyl)porphyrin [(PBTrTP)FeIIIXn], iron(III) 5,10,15,20-tetra(phenylethynyl)porphyrin [(TPEP)FeIIIXn], iron(III) 1,4-bis-[10,15,20-tri(p-tolyl)porphyrin-5-yl]-1,3-butadiyne {[(TrTP)FeIIIXn]2B}, and 5,10,15-triphenylporphyrin [(TrPP)FeIIIXn] have been studied to elucidate the impact of meso-ethynyl substitution on the electronic structure and spin density distribution of high-spin (X = Cl-, n = 1) and low-spin (X = CN-, n = 2) derivatives. The meso substituents, i.e., ethynyl, phenylethynyl, and phenylbutadiynyl, provided insight into the efficiency of spin density delocalization along structural elements that are typically applied to transmit electronic effects along multipart polyporphyrinic systems. The positive spin density localized at the meso-carbon of high-spin iron(III) ethynylporphyrins is effectively delocalized along the ethyne or butadiyne fragment as illustrated by the comparison of isotropic shifts of Cmeso−H and −CC−H determined for (TrPP)FeIIICl (−82.6 ppm, 293 K) and (ETrTP)FeIIICl (−49.5 ppm, 298 K). The replacement of the ethynyl hydrogen by phenyl or phenylethynyl provided evidence for the π spin density distribution around the introduced phenyl ring. An analysis of the isotropic shifts for the low-spin bis-cyanide iron(III) porphyrins series reveals the analogous mechanism of spin density transfer. Treatment of high-spin [(TrTP)FeIIICl]2B with a base resulted in formation of the cyclic [(TrTP)FeIIIOFeIII(TrTP)B]2 complex linked by two μ-oxo bridges. (TPEP)H2 has been characterized by X-ray crystallography as a porphyrin dication where two molecules of trifluoroacetic acid associate with two coordinated trifluoroacetate anions. The X-ray structure of bis-tetrahydrofuran 1,4-bis[10,15,20-tri(p-tolyl)porphyrinatozinc(II)-5-yl]-1,3-butadiyne complex {[(TrTP)ZnII(THF)]2B} reveals two parallel, non-coplanar [(TrTP)Zn(THF)] subunits linked by the linear butadiyne moiety

¹H NMR Investigation of High-Spin and Low-Spin Iron(III) <b><i>meso</i></b>-Ethynylporphyrins

The 1H NMR spectra of iron(III) 5-ethynyl-10,15,20-tri(p-tolyl)porphyrin [(ETrTP)FeIIIXn], iron(III) 5-(phenylethynyl)-10,15,20-tri(p-tolyl)porphyrin [(PETrTP)FeIIIXn], iron(III) 5-(phenylbutadiynyl)-10,15,20-tri(p-tolyl)porphyrin [(PBTrTP)FeIIIXn], iron(III) 5,10,15,20-tetra(phenylethynyl)porphyrin [(TPEP)FeIIIXn], iron(III) 1,4-bis-[10,15,20-tri(p-tolyl)porphyrin-5-yl]-1,3-butadiyne {[(TrTP)FeIIIXn]2B}, and 5,10,15-triphenylporphyrin [(TrPP)FeIIIXn] have been studied to elucidate the impact of meso-ethynyl substitution on the electronic structure and spin density distribution of high-spin (X = Cl-, n = 1) and low-spin (X = CN-, n = 2) derivatives. The meso substituents, i.e., ethynyl, phenylethynyl, and phenylbutadiynyl, provided insight into the efficiency of spin density delocalization along structural elements that are typically applied to transmit electronic effects along multipart polyporphyrinic systems. The positive spin density localized at the meso-carbon of high-spin iron(III) ethynylporphyrins is effectively delocalized along the ethyne or butadiyne fragment as illustrated by the comparison of isotropic shifts of Cmeso−H and −CC−H determined for (TrPP)FeIIICl (−82.6 ppm, 293 K) and (ETrTP)FeIIICl (−49.5 ppm, 298 K). The replacement of the ethynyl hydrogen by phenyl or phenylethynyl provided evidence for the π spin density distribution around the introduced phenyl ring. An analysis of the isotropic shifts for the low-spin bis-cyanide iron(III) porphyrins series reveals the analogous mechanism of spin density transfer. Treatment of high-spin [(TrTP)FeIIICl]2B with a base resulted in formation of the cyclic [(TrTP)FeIIIOFeIII(TrTP)B]2 complex linked by two μ-oxo bridges. (TPEP)H2 has been characterized by X-ray crystallography as a porphyrin dication where two molecules of trifluoroacetic acid associate with two coordinated trifluoroacetate anions. The X-ray structure of bis-tetrahydrofuran 1,4-bis[10,15,20-tri(p-tolyl)porphyrinatozinc(II)-5-yl]-1,3-butadiyne complex {[(TrTP)ZnII(THF)]2B} reveals two parallel, non-coplanar [(TrTP)Zn(THF)] subunits linked by the linear butadiyne moiety

Stereoselective Wittig Olefination as a Macrocyclization Tool. Synthesis of Large Carbazolophanes

<i>Z</i>-Selective Wittig olefination was applied to the synthesis of large carbazolophanes containing up to eight heteroaromatic subunits. A number of strategies were devised and tested, showing that cyclooligomerization yields can be significantly improved by using one-component schemes involving heterobifunctional reactants. [4]- and [6]­Carbazolophanes were characterized in the solid state, revealing compact, highly folded structures. Electronic and steric effects of substitution and chain length on the Wittig olefination rates and <i>Z</i>-selectivities were explored theoretically using DFT calculations

Discovery of Ferroelectric Properties in Diammonium Hypodiphosphate (NH₄)₂H₂P₂O₆ (ADhP)

Discovery of Ferroelectric Properties in Diammonium Hypodiphosphate (NH4)2H2P2O6 (ADhP

Stereoselective Wittig Olefination as a Macrocyclization Tool. Synthesis of Large Carbazolophanes

<i>Z</i>-Selective Wittig olefination was applied to the synthesis of large carbazolophanes containing up to eight heteroaromatic subunits. A number of strategies were devised and tested, showing that cyclooligomerization yields can be significantly improved by using one-component schemes involving heterobifunctional reactants. [4]- and [6]­Carbazolophanes were characterized in the solid state, revealing compact, highly folded structures. Electronic and steric effects of substitution and chain length on the Wittig olefination rates and <i>Z</i>-selectivities were explored theoretically using DFT calculations

Lanthanide Complexes of the Heterochiral Nonaaza Macrocycle: Switching the Orientation of the Helix Axis

The La(III), Ce(III), Pr(III), Nd(III), Sm(III), and Eu(III) complexes of the racemic heterochiral nonaaza macrocyclic amine L have been synthesized and characterized by spectroscopic methods. The X-ray crystal structures of the [PrL][Pr(NO3)6]·CH3OH and the isomorphic [NdL][Nd(NO3)6]·CH3OH complexes show that all nine nitrogen atoms of the macrocycle coordinate to the Ln3+ ion, completing its coordination sphere. The macrocycle wraps tightly around the metal ion in double-helical fashion. The structures reveal the RRRRSS/SSSSRR configuration at the stereogenic carbon atoms of the three cyclohexane rings, confirming the heterochiral nature of the parent 3 + 3 macrocycle obtained in the condensation of racemic trans-1,2-diaminocyclohexane and 2,6-diformylpyridine. The NMR spectra of the isolated complexes indicate the presence of low C1 symmetry [LnL]3+ complexes. The same symmetry is indicated by the X-ray crystal structures of Pr(III) and Nd(III) complexes, which show that for the RRRRSS enantiomer of the macrocycle L, the helix axis passes through the cyclohexane ring of RR chirality and the opposite pyridine ring. The NMR studies of complex formation in solution by the paramagnetic Pr3+ and Eu3+ ions indicate that the initially formed [LnL]3+ complexes are of C2 symmetry. For the RRRRSS enantiomer of the macrocycle L in the C2-symmetric species, the helix axis passes through the cyclohexane ring of SS chirality and the opposite pyridine ring. The C1-symmetric and C2-symmetric forms of the [LnL]3+ complexes constitute a new kind of isomers and the conversion of the kinetic complexation product of C2 symmetry into the thermodynamic product of C1 symmetry corresponds to an unprecedented switching of the orientation of the helix axis within the macrocycle framework

Discovery of Ferroelectric Properties in Diammonium Hypodiphosphate (NH₄)₂H₂P₂O₆ (ADhP)

Discovery of Ferroelectric Properties in Diammonium Hypodiphosphate (NH4)2H2P2O6 (ADhP

New Rhodium(III) and Ruthenium(II) Water-Soluble Complexes with 3,5-Diaza-1-methyl-1-azonia-7-phosphatricyclo[3.3.1.1^3,7]decane

The new water-soluble phosphine complexes of rhodium(III), [RhI4(mtpa)2]I (1), and ruthenium(II), [RuI4(mtpa)2]·2H2O (2) and [RuI2(mtpa)3(H2O)]I3·2H2O (3) (mtpa = 3,5-diaza-1-methyl-1-azonia-7-phosphatricyclo[3.3.1.13,7]decane cation), have been prepared in the reactions of RhCl3·3H2O and RuCl3·3H2O in water in the presence of phosphine and potassium iodide. Properties and reactivity of the complexes have been investigated using 1H and 31P NMR and IR spectroscopies. The complexes have also been structurally characterized by single crystal X-ray diffraction studies. The compounds [RhI4(mtpa)2]I and [RuI4(mtpa)2]·2H2O are zwitterionic octahedral complexes. The compounds were tested as catalysts for two-phase hydroformylation of 1-hexene and hydrogenation of cinnamaldehyde. Complex 1 is a selective catalyst for reduction of the CC bond while complexes 2 and 3 selectively hydrogenate the CO bond