Electronic spectra Tables

Electronic spectra (Table 1.1, Fig. 1.2) have been measnred for the orange soln-tions of (RuO ] in aqueous base from 250-600 nm. [212-215, 222], and reproduced [215, 222]. There are two at 460 and 385 nm. [212, 213, 222] or three bands in the visible-UV region, at 460, 385 and 317 nm [214, 215]. These appear to be at the same positions as those for [RuO ] but the intensities and hence the general outline of the two spectra are very different. Woodhead and Fletcher reviewed the published molar extinction coefficients and their optimum values / dm (mol" cm" ) are 1710 for the 460 nm. band, 831 for the 385 nm. band and 301 for the 317 nm. band - the latter band was not observed by some workers [214]. The distinctive electronic spectrum of ruthenate in solution is useful for distinguishing between it, [RuO ]" and RuO [212, 222]. Measurements of the electronic spectra of potassium ruthenate doped in K CrO and K SeO and of barium ruthenate doped into BaSO, BaCrO, and BaSeO (in all cases the anions of these host materials are tetrahedral) indicate that in that these environments at least the Ru is tetrahedrally coordinated. Based on this evidence it has been suggested that [RuO ] in aqueous solution is tetrahedral [RuO ] rather than franx-[Ru(0H)3(0)3] [533, 535]. Potential modulated reflectance spectroscopy (PMRS) was used to identify [RuO ] and [RuO ] " in alkaline aqueous solutions during anodic oxidation of Ru electrodeposited on platinum from [Ru3(N)Clg(H30)3] [228]. 

Energy Level Diagrams for the Lanthanide Ions, and their Electronic Spectra Table 5.1 Magnetic Moments of Ln + ions at room temperature... 

Stimulated by an interest in determining the position of sulfur in the spectrochemical series, Jorgensen prepared and studied the electronic spectra (Table 85) of [Rh(dtp)3] and [Rh(dtc)3] (dtp = (EtO)2PS2" dtc = EtjNCS )." The complexes were prepared by heating an aqueous solution of RhCl3 3H20 with the sodium salt of the ligand the addition of a small amount of ethanol to the solution (see Section 48.6.2.5.iii) allows the reaction to proceed at room temperature and yields a cleaner product. 

Azepino[l,2-fl]isoquinoline 315, finally obtained by Ebersbach s group (91HCA1095), has been described to be an unstable dark red oil that resists chromatography or crystallization but instead decomposes even at —20°C during a few hours. A small solvent influence in the electronic spectrum (Table 11) supports the assumption that dipolar structures do not significantly contribute to the ground level of potentially antiaromatic 315. 

After you compute an electronic spectrum with HyperChcni, you can use the table below to assign computed transitions and qiiali-tatively assess the accuracy of the com putation ... 

Table 1 Electron spectrum of AF Cr at points F and X for Q = 27r/a(0,1,0) in Ryd. ( as compared with the SPRKKR method )...

The results of calculations for the points F—27r/a(0, 0,0) and A —27r/a(0,0.5,0) of the Brillouin zone are listed in Table 1. It can be seen that the energy eigenvsdues differ, on the average, by S Q Ryd between the two csdculations. Such an accuracy is quite sufficient for most applications. The qualitative picture of the electron spectrum is in complete agreement with our previous SPRKKR calculation. 

Potassium hexafluororhodate(III), K3RI1F6, was obtained by Peacock (22) as a buff solid by fusion of K3Rh(N02)6 with KHF2. It was found to be diamagnetic (19), thus implying the presence of a low-spin lA g (tig) ground state. The electronic spectrum was studied by diffuse reflectance by Schmidtke (23) over the range 15—45 kK., as shown in Fig. 3, and the bands observed are listed in Table 3. 

Potassium hexafluorotechnetate(IV), K TcFg, is obtained from potassium pertechnetate via the hexabromo derivative with subsequent fusion with KHF2 (28), and the electronic spectrum (see Table 5) has been measured... 

Potassium hexafluororhenate (IV), K2ReF6, is, obtained from potassium perrhenate via K2Re(I)6 and subsequent fusion with KHF2 (45), and shows a magnetic moment of 3.3—3.4 B.M. at 298 °K (31, 46). The electronic spectrum in aqueous solution has been studies in some detail by Jergensen and Schwochau (29), and the principle features of their results are listed in Table 11. (See also Fig. 6). 

The absorption in the electronic spectrum lies in the normal range (Amax between 413 and 475 nm) (see Table I) for acyclic digermencs.60 63 75 A hypsochromic shift was observed for cyclotrigermene 75 (326 nm64). 

Alexander and Gray 70) and Caulton 71) have studied the electronic spectrum of the species [Co(CN)5] . Although direct proof is lacking, it has been affirmed that the optical and E. P. R. spectra are consistent with an essentially square p5u-amidal stereochemistry and are inconsistent with a trigonal bipyramidal structure (70). It has been claimed, however, that this species may be actually six-coordinate in water, i. e. [Co(CN)5(H20)]3- (72). The spectrum of [Co(CN)5]3. has four bands of low intensity between 10 and 32 kK, as well as two high intensity bands at higher frequence (Table 7). 

Even in the case of an organometallic compound par excellence, namely ferrocene, the situation is somewhat confused. The most extensive study of the electronic spectrum of this molecule is that of Scott and Becker (75), and the main observed bands are given in Table III where N— V denotes... 

The first Meisenheimer-type adduct in this group has been described for the reaction of methoxide ion with l-(4-nitrophenyl)-2,4-dinitropyrrole in DMSO.184 Its suggested structure, as inferred by the H-NMR spectrum, is shown by formula 151 (R = 4-nitrophenyl) (Table XXIII). Similar evidence has been obtained for R = phenyl and 3-nitrophenyl.185 In the electronic spectrum, adducts 151a,b,c (R = 4-nitrophenyl, 3-nitrophenyl, and phenyl, respectively) display a maximum in the region of 545 to 575 nm in DMSO-CH3OH (2 1, v/v).183 In contrast, for 150 (R = CH3) the reaction with CHjCT in DMSO solution consists of a quick decomposition instead of adduct formation.184 Evidence has recently been provided for the formation of adduct 152 (Table XXIII) from 2-methyl-1,4-dinitropyrrole in DMSO.186... 

The electronic spectrum of [Cr(ox)3]3 has been studied extensively both in solution and in the solid state.888,889 The assignment of the spin-allowed transitions from solution electronic spectroscopy is a popular undergraduate exercise.890 The low energy spin-forbidden 4A2—> 2E transition is readily observed for this complex.889,890 Table 81 summarizes the most significant features of the electronic spectrum. 

Table 81 The Electronic Spectrum of Potassium Tris(oxalato)chromate(III) (after ref. 889)...

Fig. 11.46 Electronic spectrum of /ronr-lCrtenhFj] transition frequencies are given in Table 11.20. [Modified from Dubicki, L., Hitchman. M. A. Day. P. hiorg. Chem. 1970, 9. 188-290. Used with permission.]...

The [Ni(CN)4]2 anion is one of the most stable nickel(II) complexes and an overall formation constant as high as about 1030 has been determined.627,62 The structure of the complex is square planar with the nickel(II) bound to carbon atoms of cyanides and with linear Ni—C—N linkages (Table 37).629 630 The planar [Ni(CN)4]2 units are stacked in columns in the crystal lattice with Ni—Ni interlayer distances as short as 330 pm. C-bonded CN- is a strong field donor and the electronic spectrum of [Ni(CN)4]2 shows two weak d-d bands at 444 and 328 nm. 

The products isolated from reactions of amides with transition metal halides usually contain coordinated halide (e.g. the formulations in Table 2). In some cases such as [Co(NMF)6][CoCLt], halide and amide are coordinated to different metal atoms, but when such compounds are dissolved in the neat ligand, halide can be replaced and at high dilution all the metal ions may be fully coordinated by the amide alone. The electronic spectrum resulting when this cobalt complex is dissolved in nitromethane has been interpreted as relating solely to the tetrahedral complex [CoC12(NMF)2]. 

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