Basic properties Benzene complexes

The lack of basic properties of bis-n-benzene chromium compared to those of ferrocene may be due in part to the reduced availability to acceptor ligands of the e2g electrons which, in -arene complexes, are quite important (see above). It is worth noting that no bent bis- -arene complexes are presently known (e.g., no ( i-C[Pg.178]

With liquid crystal metal phthalocyanine compounds as mass sensors, the LSER approach has proven useful. Analyte uptake has been measured using QCM methods, and adsorption of volatile organic compounds (VOCs) into the liquid crystalline coating appears to follow similar trends as for organic polymer film sensors. It should be noted that the analytes examined (toluene, chloroform, carbon tetrachloride, benzene, hexane, and methanol) are volatile compounds that are very weak ligands toward metals [167], Thus, the composite sensor response for metal phthalocyanine sensors based on conductivity is a complex property that depends on analyte redox properties, basicity, and sensor crystallinity. 

The ability to bind the additional amount of aromatic hydrocarbons is also characteristic of complexes with other binary acid systems, for example, of the complexes A HF BFj. This property of ternary complexes can be used to separate aromatic hydrocarbons from saturated ones and to separate aromatic hydrocarbons differing in their basicity (for the use of complexes with HCl and AlCl, see > with HF and BF3 see ° )- References recording the formation of the ternary complexes A HY mMY and of their solvates for hydrocarbons of the benzene series are listed in Table 1. 

The nature of the solvent influenced the equilibrium formation constant and subsequent rate-determining conversion to products for an intermediate complex, formed between the substrates and PDA these constants were reported for reactions in acetone and benzene. Equations correlating the rates of Py oxidation with the solvent properties are reported the rates are affected by the basicity and polarity, unaffected by polarizability and electrophilicity, and appreciably retarded by added AcOH.234... 

Foregoing results support the view that the "bis-roof structure is brought forth by the Cr(CO)3-enhanced steric crowding on the lower rim. One of the characteristics of this structure is that the p-carbon in benzene A is very close to that in benzene C (only 3.88 A for cone-l Cr(CO)3 and 3.81 (3.72) A for cone-l 2Cr(CO)3) whereas two p-carbons in benzenes B and D are very far (10.14 A for cone-l Cr(CO)3 and 10.25 (10.10) A for cone-l 2Cr(CO)3). The unusual intramolecular proximity between confronting benzene units may be reflected by some spectral properties of the complexes. We examined the IR spectra (CH2CI2 solvent) of cone-l Cr(CO)3 and cone-l 2Cr(CO)3. We found that the Vc=o bands for cone-l Cr(CO)3 (1951 and 1868 cm ) shift to lower wavenumber than those for cone-l 2Cr(CO)3 (1961 and 1880 cm ). The shift to lower wavenumber means that the 7C-basicity in the Cr(CO)3-carrying benzene unit in cone-l Cr(CO)3 is higher than that in cone-l 2Cr(CO)3[30]. We consider that the difference is induced by the difference in the transannular interaction that is, in cone-l Cr(CO)3 benzene A and benzene C act as an electron-acceptor and an electron-donor, respectively and interact with each other transannularly. 

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