Physical and Spectroscopic Data

All nitronaphthyridines are solids with relatively high melting points (see Table III). Mononitronaphthyridines without other substituents are moderately soluble in hot water from which they can be recrystallized. 

The pKa value of 3-nitro-l,5-naphthyridine is 0.63. The ionization constants for protonation at N-l (pAT,) and N-5 (p/O) of 3-nitro-l,5-naphthyri-dine are pKt = 0.98 and p/C = 0.48 and for 3-nitro-l,5-naphthyridin-2(lH)-one (pKa = 0.26) p/C, = 6.35 and pK5 = 0.67 were calculated using the modified Hammet equation. It was concluded by comparison of these results that protonation takes place at the ring-nitrogen in position 5 yielding 166a and 166b respectively (77KGS965). 

77-Electron Stabilization Energy (AE) Calculated According to Eq. (A) for 3-Nitronaphthyridines 

Formal Electron Charges q on the Annular Atoms of the 3-Nitronaphthyridines 

4- amino-3-nitro-l, 8-naphthyridine l-iV-ethyl-3-nitro-l,8-naphthyridin- 

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Chemical, physical and spectroscopic data all suggest a periodic table as shown on p. (/T. 

The three-step sequence used to convert enone 65 to miltirone (56) is shown in Scheme 5.7 and consists of, first, a Wolff-Kishner reduction to convert the C(5) carbonyl moiety into a methylene, followed by deprotection of the aryl methyl ethers and oxidation to an ortho-quinone using ceric ammonium nitrate. The physical and spectroscopic data of our synthetic miltirone are identical with those reported for the natural material. 

All the compounds were identified by physical and spectroscopic data and comparison with literature data (3,6). The structure of the new benzoxazole 6 was based on spectroscopic data and synthesis of its acetylated derivatives, and confirmed by X-ray crystallographic analysis. 

Besides the phosphoranes, the homoleptic amides of niobium(V) and tantalum(V) are the only pentamides known.1 These compounds, exemplified by M(NMe2)5 (M = Nb, Ta) are volatile, hydrocarbon-soluble solids.37 All physical and spectroscopic data are consistent with a strictly mononuclear existence for these complexes. 

The simple phenoxides M2(OPh)10 (M = Nb, Ta) similarly behave as dimers in solution,187 while there is H NMR and IR spectroscopic evidence for the terminal and bridging aryloxides.188 With the more sterically demanding 2,6-dimethylphenoxides M(OAr)s, physical and spectroscopic data are consistent with their being monomeric. 

Hexaalkoxides are only known for the two elements tungsten and uranium. In both cases, physical and spectroscopic data are consistent with monomeric, octahedral complexes. Tungsten hexaalkoxides are pale yellow or colorless substances that readily sublime and exhibit the expected H NMR and mass spectra.189 The totally symmetric v(W—O) stretch occurs between 530 and 600 cm-1 in the IR spectrum, depending on the alkyl substituents. In contrast, the homoleptic phenoxide W(OPh)6 is intense red in color due to the presence of a strong oxygen-to-metal charge transfer band in this d° complex which absorbs in the visible part of the spectrum.36... 

Table 1 Physical and Spectroscopic Data of Thiocarboxylic Esters...

It is relevant that attention should now be drawn to the recent work, by Patterson, Pyke, Reid, Tilley, McAteer, et al. (12-16), who have examined several aspects of the structural and catalytic character of coprecipitated tin-antimony oxides. The structure characterization by Pyke, Reid, and Tilley (12) by X-ray diffraction techniques clearly showed that bulk equilibrium is difficult to establish in this system. This observation alone places some earlier data in a different perspective and implicitly demands a high degree of caution in the interpretation of physical and spectroscopic data recorded from these materials. The phase diagram (Fig. 1) defines the... 

Preliminary physical and spectroscopic data on securitinine indicated that it possessed all the basic features of securinine and, in... 

The physical and spectroscopic data of several linear and angular annelated indoles have been described in detail in the period from the mid-1980s to the mid-1990s. The heterocyclic ring system... 

Confirmation of the conclusions drawn above for the cis- and /rans-isomers (14 R = R2 = OMe, X = H2) and (15 R = R = OMe, X = H2) from physical and spectroscopic data was obtained by exhaustive Hofmann degradation. As required, both isomers yielded the same mixture of isomeric non-nitrogenous compounds(20). Finally, trans-base (15 R = = OMe,X = H2)... 

Table II lists molecular formulas, melting points, specific rotations, and references related to physical and spectroscopic data for all naturally occurring cularine and related alkaloids isolated up to date. Most of the data included in previous reviews in this treatise (/, 2) have been excluded.

Phosphorus(y) Compounds. The preparation and properties of compounds containing the phosphazotrihalide, N=PX3, grouping have been reviewed, and physical and spectroscopic data for the compounds have been tabulated. ... 

Table 3.8. Physical and spectroscopic data of thiophene oligomers [42a]... 

There have been a few reports of simple lanthanide alkyl and aryl compounds (see table 25.19). The structure of the Lu(CgH9)4 anion (CgHf = 2,6-dimethyl-phenyl ion) was discussed earlier (section 3.3). Hart and his co-workers (Hart et al., 1970a) have described some trimethyl and triphenyl complexes as well as some more complicated compounds of formula LiR(C6Hj)4. There is reasonable chemical evidence for the formation of these compounds but more physical and spectroscopic data are needed. 

Table 1. Synthetic Routes and Selected Physical and Spectroscopic Data for Carboxylate Substituted Alumoxanes...

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