Drago complex

The second problem involves the measurement of pKa values for carbonyl and thiocarbonyl derivatives. Grieg and Johnson (157) have pointed out that the measurement of pKa values for very weak bases (11) is an inaccurate and arbitrary process. Of particular difficulty for our purposes is the fact that different carbonyl derivatives may require different acidity functions. As a result of this situation, no attempt was made to make correlations of pKa data for carbonyl and thiocarbonyl derivatives with eq. (2). Because accurate pKa values can be measured for imines, these values were correlated with eq. (2), although the conformational problem remains. The imine sets were first studied by Charton and Charton (73), who correlated them with eq. (2). No correlations of data for carbonyl or thiocarbonyl derivatives with eq. (2) are extant in the literature. Bhaskar, Gosavi, and Rao (158) have reported that AG values for complex formation of substituted thioureas with iodine are a linear function of the Taft a values. Drago, Wenz, and Carlson (159) have reported similar results for complex formation between iodine and substituted amides. Oloffson (160) has reported a linear relationship between -AH for the complex of substituted N,N-dimethylamides with SbCls and the ffj constants. 

Drago and coworkers have also calculated the enthalpy values for the formation of many complexes or hydrogen bonds by NMR and calorimetric techniques. For example, in a series of phenols or t-BuOH, they observed the IR frequency shifts (Avqh) of the hydroxyl compounds and found that a linear relationship exists between bases and individual acids. In Table 7 shows some AH values calculated by equation 2, and Avqh values of t-BuOH" " while in Table 8 frequency data Avq of various substituted phenols and the AH values are given. 

Eaq and Caq are the tendency of acid A and base B to undergo ionic and covalent bonding, respectively. Equation (2) resembles that proposed by Drago et al. (18) to model heats of complex formation of acids and bases in solvents of low dielectric constant. Only Lewis acids of ionic radius greater than 1.0 A obey Eq. (2). For all smaller Lewis acids, a third pair of parameters has to be introduced ... 

First of all, quantum calculations allow one to predict basicity scales in agreement with experiment provided that the calculations are performed on the preferred conformation of the isolated molecule. If this is not done, a given term within a consistent series may jump from one rank to another as a function of the conformation used for the calculations. The determinant role of preferred conformation on any property (barrier to internal rotation and inversion, dipole moment, first adiabatic ionization potential, acidity and basicity in the gas phase, energy of complexation to BF3, etc.) was clearly demonstrated. We further show the importance of the role of preferred conformation in explaining some of the anomalies in Drago s systematics. 

An alternative strategy for catalyst immobilisation uses ion-pair interactions between ionic catalyst complexes and polymeric ion exchange resins. Since all the rhodium complexes in the catalytic methanol carbonylation cycle are anionic, this is an attractive candidate for ionic attachment. In 1981, Drago et al. described the effective immobilisation of the rhodium catalyst on polymeric supports based on methylated polyvinylpyridines [48]. The activity was reported to be equal to the homogeneous system at 120 °C with minimal leaching of the supported catalyst. The ionically bound complex [Rh(CO)2l2] was identified by infrared spectroscopic analysis of the impregnated resin. 

Teper Y, Whyte D, Cahir E, Lester HA, Grady SR, Marks MJ, Cohen BN, Fonck C, McClure-Begley T, McIntosh JM, Labarca C, Lawrence A, Chen F, Gantois I, Davies PJ, Petrou S, Murphy M, Waddington J, Home MK, Berkovic SF, Drago J (2007) Nicotine-induced dystonic arousal complex in a mouse line harboring a human autosomal-dominant nocturnal frontal lobe epilepsy mutation. J Neurosci 27 10128-10142... 

The TiF4 and Pr 2NH, Et2NH, py or NMe3 systems have been shown to be quite complex by Drago and coworkers.45 For example, in TiF4-rich solutions in acetone, high conductance has been explained by equation (10). 

The complex [Cr(DMS0)6]jCl04]3 was first prepared by Cotton in 1959941 as green needles by reacting concentrated Cr(C104)3 solutions with DMSO. Subsequently Drago established the spectrochemical series for chromium(III) to be H20 > DMSO > TMSO > QHsNO.942 A... 

Multinuclear complexes often have low solubility Drago and co-workers have described an anion-bridged soluble dinuclear chelating system based on 4-t-butyl-2,6-bis[JV- [(heptylthio)-thiocarbonyl]amino formimdoyl]phenol. 1... 

Drago el al. (96, 14 16) employed calorimetry and III and PMR methods to measure the stability constants and heats of formation of Me3SnCl complexes with dimethyl sulfoxide, dimethylacctamide, DMF, acetonitrile, pyridine, and HMPT (sec Table XIV). 

The cobalt(n) complexes of protoporphyrin-IX dimethylester and mesoporphyrin-IX dimethylester have been reduced polarographically.113 The original study by Stynes and Ibers114 of the oxygenation of the amine complexes of cobalt(n) protoporphyrin-IX dimethylester has been criticized by Guidry and Drago,115 who suggest that the treatment of the data was incorrect and that the system is ill-defined. Ibers et al.116 have reconsidered their data and claim that this substantiates the earlier work and proves that the system is clearly defined. 

Rhodium complex was loaded onto the quatemised polymer support by the reaction with [Rh(CO)2I]2 in hexane (Eq 2). The resulting polymer beads or films showed the characteristic yellow colour of [Rh(CO)2I2] . An infrared spectrum of the powdered beads (KBr disk) showed two weak v(CO) absorptions of similar intensity at 2056 and 1984 cm 1, consistent with the presence of the cis-dicarbonyl complex, [Rh(CO)2I2]" (2059, 1988 cm 1 in CH2C12). Spectra of a much higher quality and intensity were obtained from polymer films loaded with rhodium complex. These observations of polymer supported [Rh(CO),I,r match those reported in the original study of Drago et al. 

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