Silicon complexes phthalocyanines

An important area of research in silicon phthalocyanine chemistry has been the preparation of conducting polymers through Si—O—Si links.In one recent example, silicon phthalocyanine complexes have been appended to a den-drimer framework through Si—O—C(triazine) bonds formed by reaction of the salt Na [Si(Pc)(Ph)0 ] with a dichlorotriazine derivative. 

A dye molecule that has found widespread attention in the synthetic metals community is phthalocyanine 186, which can be readily made from ortho-dicyanobenzene 187 in a metal-assisted cyclotetramerization that directly provides metal complex derivatives 188 (see scheme 44) [251]. A tuning of the electronic properties is possible via the central atom and, for example, by proceeding to the related tetranaphthalene compound 189 [252]. The importance of phthalocyanines 188 in both fundamental and industrial research comes from the great number of possible applications [253]. Also, 188 can be stacked into columnar arrays by using axial ligands at the metals or by linking silicon centers as central atoms by suitable spacers [254]. The introduction of long chain alkoxy... 

Dichlorosilicon phthalocyanine (XIX) is prepared from silicon tetrachloride and phthalonitrile in quinoline at 200°C 168,170). The blue-green crystals, which sublime readily at 430°C in vacuo, hydrolyze forming dihydroxysilicon phthalocyanine (XX) when refluxed with equal volumes of pyridine and aqueous ammonia (200). The corresponding difluorosilicon phthalocyanine is resistant to hydrolysis. Conversion of the chloride to the corresponding dicyanate, dithiocyanate, and diselenocyanate occurs upon reaction with the appropriate silver pseudohalide (178). The complexes are believed to involve nitrogen to silicon bonding in the case of the thiocyanate and selenocyanate. 

Thus (XX) reacts with phenol in pyridine to form diphenoxysilicon phthalocyanine (XXII), with benzyl alcohol to form (XXIII), and with triphenylsilanol to form (XXIV) (168,170, 200). These complexes sublime readily without decomposition (cf. corresponding aluminum derivatives). Bis(diphenylmethylsiloxy)silicon phthalocyanine, which melts before subliming, is one of the very few metal phthalocyanines which actually melt (873). The siloxy complex (XXIV) may also be prepared in benzyl alcohol, thus implying that the Si—O—Si(Pc)—0—Si backbone is more stable than C—O—Si(Pc)—O—C. The dibenzyloxy derivative (XXIII) reacts with diphenylsilanediol to form bis(benzyloxydiphenylsiloxy)silicon phthalocyanine (XXV). 

Cartoni et al. [88] studied perspective of the use as stationary phases of n-nonyl- -diketonates of metals such as beryllium (m.p. 53°C), aluminium (m.p. 40°C), nickel (m.p. 48°C) and zinc (liquid at room temperature). These stationary phases show selective retention of alcohols. The retention increases from tertiary to primary alcohols. Alcohols are retained strongly on the beryllium and zinc chelates, but the greatest retention occurs on the nickel chelate. The high retention is due to the fact that the alcohols produce complexes with jS-diketonates of the above metals. Similar results were obtained with the use of di-2-ethylhexyl phosphates with zirconium, cobalt and thorium as stationary phases [89]. 6i et al. [153] used optically active copper(II) complexes as stationary phases for the separation of a-hydroxycarboxylic acid ester enantiomers. Schurig and Weber [158] used manganese(ll)—bis (3-heptafiuorobutyryl-li -camphorate) as a selective stationary phase for the resolution of racemic cycUc ethers by complexation GC. Picker and Sievers [157] proposed lanthanide metal chelates as selective complexing sorbents for GC. Suspensions of complexes in the liquid phase can also be used as stationary phases. Pecsok and Vary [90], for example, showed that suspensions of metal phthalocyanines (e.g., of iron) in a silicone fluid are able to react with volatile ligands. They were used for the separation of hexane-cyclohexane-pentanone and pentane-water-methanol mixtures. 

Poly-yne polymers composed of phthalocyanine (Pc) complexes (42) with silicon were synthesized (equation 40) by Mitulla and Hanack. The conductivities of the polymers were up to 10 S cm", and increased to 10 S cm by I2 doping. 

Another interesting material consists of the doped forms of covalently linked siloxane-phtha-locyanine (Pc) complexes, [Si(Pc)0]n. In these polymers, the planar phthalocyanine units are apparently stacked face-to-face and form columns, due to the silicon-oxygen-silicon bonds. The polymers appear to be intrinsically metallic systems. The principal pathways of conductivity are perpendicular to the phthalocyanine planes. The extended n-n systems that form result from face-to-face overlaps of the phthalocyanine units. This enables the electrons or holes to travel in a perpendicular direction. 

Figure 5. Structure of iron(phthalocyanine) within the faujasite cavity as calculated via molecular mechanics. Carbon and hydrogen atoms of the metal complex are shown as unshaded dark and open circles respectively. Silicon and oxygen atoms of the zeolite are shown as shaded circles. Two views are given, (a) Along the S4 direction in the cavity with two phenyl rings of the metal complex emerging from the tetrahedral holes in the direction of the viewer and the other two rings in the tetrahedral holes away from the viewer, (b) Perpendicular to the S4 axis showing phenyl rings in their tetrahedral holes. The backbone of the metal complex and faujasite cavity are shown.

Three publications deal with the synthesis of p-oxo-linked silicon phthalocyanine and porphyrin derivatives. The stepwise syntheses of p-oxo-linked hetero-chromophore arrays containing phthalocyanine, porphyrin, and sub phthalocyanine silicon and germanium complexes have been described [306, 307]. The p-oxo... 

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