Syntheses and Properties of Cerium Diphthalocyanines in High Oxidation States; Crystal Structure of [Ce(Pc)₂](BF₄) 0.33

Abstract

Ring oxidized green Cerium(IV)diphthalocyanines, [Ce(Pc)2]X (X = (poly)halide, NO3-) are prepared by chemical oxidation of (nBu4N)[Ce(Pc2-)2] with the corresponding halogen in solution or of solid [Ce(Pc2-)2] with aqueous HNO3 Electrochemical oxidation of (nBu4N)[Ce(Pc2-)2] in solution in the presence of (nBu4N)BF4 yields [Ce(Pc)2](BF4)0.33, which crystallizes in the tetragonal space group P4/nnc (a, b = 19.643(3) Å, c = 6.525(3) A, Z = 2). The CeIV ion is eightfold coordinated by the isoindole N atoms (Niso) of the two staggered (ca. 41°), slightly distorted Pc ligands. The “[Ce(Pc)2]0.33+” subunits are arranged in infinite columns along [001] with the Ce atoms statistically disordered over two positions and Ce - Niso bond lengths of 2.45(1) and 2.69(1) A, respectively The UV-VIS spectrum is dominated by the transitions of the Pc2- ligand at ca. 15,000 (B band), 30,000 and 36,000 cm -1 (Q, N region). A low energy (“metallic”) band at ca. 2800 cm -1 typical for partially oxidized systems is present. The UV-VIS-NIR spectrum of [Ce(Pc)2]NO3 indicates a cofacial Pc2- - P c- complex. In addition to the π-π’ transitions of the Pc2- moiety at ca. 14,000, 30,000 and 36,000 cm-1, the Ch transition of the Pc- ring is observed at ca. 19,200 cm -1 and the typical NIR band at 6380 cm -1. Oxidation of a thin film of (PNP)[Ce(Pc2-)2] with dry Br2/ N2 gas yields purple [Ce(Pc-)2]Brx, whose UV-VIS-NIR spectrum shows the diagnostic features of dimeric Pc- radicals with intense bands at ca. 14,000 and 18,000 cm -1 assigned as B and Q1 bands, respectively. At ca. 9000 cm-1 the typical QD absorption is observed. The vibrational spectra are dominated by the transitions of the Pc- ligand at 1305/1445 cm -1 (IR) and 560/1120/1172/1591 cm-1 (resonance Raman). Excitation with 1064 nm strongly enhances the sym. C e-N stretch at 163 c m -1.

Electrochemically controlled multistability of ultrathin films of double-decker cerium phthalocyaninates

“…And a spe cial configuration stability of the 4f 0 free shell makes the tetravalent state of cerium ion very stable. Based on the linear correlations between the positions of the bands in the spectra of lanthanide bis tetra 15 crown 5 phthalocyaninates and their ionic radii, taking into account differences in ionic radii of Ce 3+ (0.1143 nm) and Ce 4+ (0.0970 nm), we have shown that in the solu tion of studied homoleptic complex the cerium mainly exhibits valent state IV, and the complex has the fol lowing electronic structure: Ce 4+ [R 4 Pc 2-] 2 [22,33]. The spectral similarity of the considered homo and heteroleptic cerium complexes suggests that hetero leptic complex in solution has a similar electronic structure:…”

“…The intensity of this band in the spectra of cerium double decker complexes increases in the presence of electron donor substituents in the phthalocyanine macrocycle [8,10,20,26,33], which agrees well with the smaller relative intensity of the band at 500 nm in the spectra of heteroleptic complex that has 4 elec tron donating crown ether groups, instead of 8. It is known that cerium atom in the sandwich phth alocyaninates can exhibit two different oxidation states: +3, as all members of the lanthanide series exhibit, and +4 due to the involvement of the 4f orbital electron in interactions [19][20][21][22][23][24]. And a spe cial configuration stability of the 4f 0 free shell makes the tetravalent state of cerium ion very stable.…”

“…The ability of the cerium ion in the sandwich bisph thalocyaninates to exhibit not only +3 oxidation state that is characteristic for lanthanides, but also +4 [19][20][21][22][23][24] marks complexes of cerium out of the lanthanide sub stituted bisphthalocyaninate series. This phenomenon increases the number of stable states of the complex and, thus, extends the functionality of the supramo lecular devices based on this compound.…”

Electro‐Conductive Single‐Molecule Magnet Composed of a Dysprosium(III)‐Phthalocyaninato Double‐Decker Complex with Magnetoresistance

“…Even for MPc 2 systems, semiconductor‐like behavior has been reported from room to low‐temperature regions when the metal (M) ions are In 3+ , Zr 4+ , and U 3+ , [26] and low‐temperature conduction properties are expected for 1D stacked DyPc 2 complex. There have been several reports on partially oxidized 1D [LnPc 2 ]I x complexes (Ln=Ce, Pr, Sm, Ho and Yb) [27–31] . In these reports, [LnPc 2 ]I x is synthesized using harsh oxidation conditions in ampules containing phthalonitrile, Ln powder and iodine above 200 °C.…”

Orientation-induced redox transformations in Langmuir monolayers of double-decker cerium bis[tetra-(15-crown-5)-phthalocyaninate] and multistability of its Langmuir-Blodgett films

“…1), ultrathin films of which are studied in this work. Ce(R 4 Pc) 2 differs from other substituted bis(phthalocyaninates) in the fact that the oxidation state of the metal center can be equal not only to 3+, which is typical for lanthnides series, but also to 4+ [6][7][8][9][10][11]. This circumstance makes it possible to increase the number of the stable states of the com plex, that widens the functional potential of supramo lecular devices assembled on its basis.…”