Narrow Results

The hydrothermal assembly of a very stable porphyrin network with nanoscale cavities is described. A tightly packed and interpenetrated, linear polymeric framework was observed in the solid-state X-ray structure of freebase 5,10,15,20-tetrakis-(4-carboxyphenyl)porphyrin coordinated to calcium(II) ions. Strong hydrogen-bonding interactions between the coordination polymers form a two-dimensional network. Perpendicular bands interpenetrate generating an unusual three-dimensional box that clathrates a pyridine molecule.

The complexes of cobalt(II) tetraphenylporphyrin (Co^IITPP) with fullerenes C₆₀, C₇₀ and C₆₀(CN)₂ are presented. It is shown that Co^IITPP forms complexes with fullerenes in different solvents: [Co^IITPP•fullerene•solvent] (solvent = C₆H₆, C₆H₅Me, C₆H₄Cl₂, CS₂, CHCl₃). The use of additional donors (Cp₂Fe, Cr⁰(C₆H₆)₂, and TDAE) in the synthesis of Co^IITPP/fullerene complexes allows one to obtain multi-component complexes ranging from neutral [(Co^IITPP•Py)₂•Cp₂Fe•fullerene•solvent] to ionic [Co^IITPP•(D₂^•+)•(fullerene^•−)•solvent] (D₂ = Cr^I(C₆H₆)₂, TDAE). The interaction of Co^IITPP with neutral and negatively charged fullerenes is considered. The neutral Co^IITPP/fullerene complexes are characterized by a secondary M…C(fullerene) bonding with the shortest Co…C contacts in the 2.69-2.82 Å range and noticeable changes in the electronic structure of the parent components. At the same time, σ-bonding is observed in ionic complexes between Co^IITPP and fullerene radical anions with the shortened Co…C contacts being in the 2.28-2.32 Å range. The resulting (Co^IITPP•fullerene⁻) anions are diamagnetic. The σ-bonding is relatively weak and the (Co^IITPP•fullerene⁻) anions begin to dissociate above 200 K.

The crystals of the ionic complex containing fullerene C₆₀²⁻ dianions and positively charged (MDABCO⁺)₂·Mn^IITPP assemblies: {(MDABCO⁺)₂·Mn^IITPP}·(C₆₀²⁻)·(C₆H₄Cl₂)₄·(CH₃CN)₂ (1) were obtained for the first time (MDABCO⁺: the cation of N-methyldiazabicyclooctane; TPP: tetraphenylporphyrin). The C₆₀²⁻ dianions are isolated in the complex with the shortest center-to-center distance of 13.228 Å. The Mn^II atoms are six-coordinated in the (MDABCO⁺)₂·Mn^IITPP units. The length of the Mn-N(TPP) equatorial bonds of 2.093-2.098(1) Å corresponds to the high-spin state of the Mn^II atoms (S = 5/2) which was confirmed by the magnetic measurements (µ_eff = 5.61 µ_B at 300 K). The Mn^II atoms are located exactly in the porphyrin plane and this results in the radial expansion of the porphyrin core. The long (2.537(1)−2.545(1) Å) Mn-N(MDABCO⁺) axial bonds indicate essential destabilization of the six-coordinated (MDABCO⁺)₂·Mn^IITPP units due to the population of the d(z²) orbital in high-spin state. The contribution from the C₆₀²⁻ dianions was not found in magnetic measurements on the basis of the contribution from high-spin Mn^IITPP and most probably they are diamagnetic in the 2-300 K range.

The complex of fullerene C₆₀ with dipyridinated iron(II) phthalocyanine [Fe(II)Pc(C₅H₅N)₂]·C₆₀·4C₆H₄Cl₂ (1) has been obtained as single crystals. According to the IR- and UV-visible-NIR spectra, 1 is molecular solid with no charge transfer from Fe(II)Pc(C₅H₅N)₂ to C_60·C₆₀ molecules form closely packed linear columns in 1 along the b axis with a uniform interfullerene center-to center distance of 9.99 Å and multiple short van der Waals (vdW) C…C contacts between fullerenes of 3.10–3.18 Å. Totally each Fe(II)Pc(C₅H₅N)₂ unit is surrounded by four C₆₀ molecules two of which form short vdW C…C contacts with the phthalocyanine plane locating near two adjacent phenylene substituents of Fe(II)Pc. The Fe(II)Pc(C₅H₅N)₂ geometry remains almost unchanged as compared with that of fullerene free Fe(II)Pc(C₅H₅N)₂. The iron(II) atoms are located exactly in the Pc plane, the Fe-N(C₅H₅N) bond length is 2.038(3) Å and the averaged of the Fe-N(Pc) bond length is 1.935(3) Å. Bisaxially coordinated iron(II) phthalocyanine complex with acetonitrile Fe(II)Pc(CH₃CN)₂ does not cocrystallize with C₆₀. Nevertheless, good quality crystals of [Fe(II)Pc(CH₃CN)₂]·2C₆H₄Cl₂ (2) were isolated in this synthesis. That is the first structure of bisaxially coordinated metal phthalocyanine complex with nitrile containing solvent. Acetonitrile unusually strongly coordinates to Fe(II)Pc with the Fe–N(CH₃CN) bond length of 1.938(1) Å. The iron(II) atoms are located in the Pc plane and the averaged length of the Fe-N(Pc) bonds is 1.934(1) Å.

By the co-crystallization of trimesic acid, TMA, with molecules such as dimethylamine, N,N,N′,N′-tetramethylethylenediamine and methanol, it has been possible to generate hydrogen-bonded four-membered networks of TMA. The three-dimensional arrangement of the four-membered networks gives rise to channels occupied by the guest molecules. It has also been possible to generate a four-membered network by co-ordination of TMA with Co(II).