Dianionic Titanyl and Vanadyl (Cation⁺)₂[M^IVO(Pc⁴⁻)]²⁻ Phthalocyanine Salts Containing Pc⁴⁻ Macrocycles

Abstract

In this study, the titanyl and vanadyl phthalocyanine (Pc) salts (Bu N ) [M O(Pc )] (M=Ti, V) and (Bu MeP ) [M O(Pc )] (M=Ti, V) with [M O(Pc )] dianions were synthesized and characterized. Reduction of M O(Pc ) carried out with an excess of sodium fluorenone ketyl in the presence of Bu N or Bu MeP is exclusive to the phthalocyanine centers, forming Pc species. During reduction, the metal +4 charge did not change, implying that Pc is an non-innocent ligand. The Pc negative charge increase caused the C-N(pyr) bonds to elongate and the C-N(imine) bonds to alternate, thus increasing the distortion of Pc. Jahn-Teller effects are significant in the [eg(π*)] dianion ground state and can additionally distort the Pc macrocycles. Blueshifts of the Soret and Q-bands were observed in the UV/Vis/NIR when M O(Pc ) was reduced to [M O(Pc )] and [M O(Pc )] . From magnetic measurements, [Ti O(Pc )] was found to be diamagnetic and (Bu N ) [V O(Pc )] and (Bu MeP ) [V O(Pc )] were found to have magnetic moments of 1.72-1.78 μ corresponding to an S=1/2 spin state owing to V electron spin. As a result, two latter salts show EPR signals with V hyperfine coupling.

{CpFeII(CO)2SnII(Macrocycle•3–)} Radicals with Intrinsic Charge Transfer from CpFe(CO)2 to Macrocycles (Cp: Cp or Cp*); Effective Magnetic Coupling between Radical Trianionic Macrocycles•3–

“…Noticeable elongation of the C–N pyr bonds is observed in the radical trianionic state (by 0.02 Å on an average). 4e Moreover, alternation of the C–N imine (for Pc and Nc) 4,5 or the C–C meso bonds (for TPP) 14 is also manifested in such a way that four bonds belonging to two oppositely located isoindole (Pc and Nc) or pyrrole (TPP) units become short and four other bonds belonging to two other oppositely located units become long. The difference between average short and long bonds of 0.03–0.04 Å essentially exceeds the 3σ value, where σ is the standard deviation in the lengths of these bonds.…”

“…2c Reduction of metal macrocycles results in the formation of radical trianions with S = 1/2 spin state. When such radical trianionic macrocycles are packed in π-stacking dimers or two-dimensional (2D) layers with effective π–π interaction between them, strong enough magnetic coupling of spins can be attained with exchange interaction ( J / k B ) up to −255 K 4 or even stronger for the naphthalocyanine (Nc) radical trianions. 5 In these salts, counter cations are present to compensate negative charge and solvent molecules are frequently involved in the crystals to occupy vacancies in the packing of the ionic components.…”

Salt of Ring‐Reduced Iron(II) Octaethyltetrapyrazinoporphyrazine Containing Trimetallic Dianions with Peripherally Coordinated ZnCl2 Units: {FeII(TPyzPzEt8)4–(ZnCl2)2}2–

“…Reduction of dianionic phthalocyanine and tetrapyrazinoporphyrazine macrocycle to the radical trianionic and tetraanionic state leads to a strong blue shift of both Soret and Q‐bands and the appearance of new bands in the NIR range at 930–1070 nm , . As a rule, the intensity of the NIR bands for the tetraanionic macrocycle is essentially weaker in comparison with that for the radical trianionic macrocycle , . The bands in the NIR range appear due to that electron injection to LUMO allows new low‐energy transitions from this partially occupied level to the LUMO + 1 level.…”

“…Potentially reduced metal phthalocyanines can also manifest promising conducting and magnetic properties. Metal macrocycles can be reduced successfully by strong reductants such as Na/Hg, potassium graphite (KC 8 ) , , LiCp * , decamethylchromocene,, and sodium fluorenone ketyl . Zinc dust can also be used as suitable reductant especially to obtain reduced compounds of iron(II) phthalocyanine or hexadecachlorophthalocyanine , …”

Molecular Structure, Optical and Magnetic Properties of Iron Tetra(2,3-quinoxalino)porphyrazine [(N-MeIm)2FeI{T(2,3-Q)Pz}•3-]}•2- Radical Dianions

“…[7] Reduction chemistry of metal macrocycles have been studying only recently. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] Recently it was shown that in salts obtained by reduction of iron(II) phthalocyanine and iron(II) hexadecachlorophthalocyanine macrocycles pack in layers, [22,23] one-dimentional chains [22] or closely packed p-p stacking columns. [24] In these salts only iron(II) atomes are reduced, no electron transfer to the phthalocyanine macrocycles is observed even inspite of the presence of sixteen chlorine atoms on periphery of macrocycle which increase essentially acceptor propertie of the macrocycle.…”