Visible spectra of complexes

Figure 20. UV-visible spectra of complex Co4(p3-0)4(p-02CMe)4(py)4 as (a) IO M and (b) lO M solutions in MeOH and (c) Co(lll)-CMS4 in nujol mull [27c],...

Manganose(II) chromate with amines Molar conductance, ir, magnetic susceptibility, UV and visible spectra of complexes 168... 

Comparison of the photoelectron spectra and electronic structures of M-NS and M-NO complexes, e.g., [CpCr(CO)2(NX)] (X = S, O), indicates that NS is a better a-donor and a stronger r-acceptor ligand than NO. This conclusion is supported by " N and Mo NMR data, and by the UV-visible spectra of molybdenum complexes. 

Upon complexation, shifts in the UV-visible spectra of cupric chloride are manifested as a shoulder at approximately 370 nm, and a shift in the visible absorption from 865 to 850 nm. The method of continuous variation7 (Job s Method) was employed using the new, 370 nm, absorption. The results indicate one monomer residue (pyridine... 

The Soret, a and j3 bands in the visible spectra of platinum(IV) porphyrin complexes occur at longer wavelengths than their platinum(II) analogues,482 H NMR resonances are all shifted downfield,482 the 13C resonances of the a carbons are shifted upheld, and the H-195Pt and 13C-195Pt coupling constants are reduced.480 Whereas excitation of platinum(II) porphyrin complexes... 

An optically transparent thin-layer electrode (OTTLE) study18 revealed that the visible spectra of the reduced forms of [Ru(bipy)3]2+ derivatives can be separated into two classes. Type A complexes, such as [Ru(bipy)3]2+, [Ru(L7)3]2+, and [Ru(L )3]2+ show spectra on reduction which contain low-intensity (e< 2,500 dm3 mol-1 cm-1) bands these spectra are similar to those of the reduced free ligand and are clearly associated with ligand radical anions. In contrast, type B complexes such as [Ru(L8)3]2+ and [Ru(L9)3]2+ on reduction exhibit spectra containing broad bands of greater intensity (1,000 [Pg.584]

Figure 25 Comparison of the UY-visible absorption spectra of complexes (22), (24), and (43) in ethanol...

Fig. 5. UV-visible spectra of recombinant Rhodnius NP4 (pH 8.0) (a) without ligand (solid line) and NO complex (dashed line) (b) without ligand (solid line) and histamine complex (dashed line). Reproduced with permission from Ret (48).

The visible spectra of oxyHr and metIh N3 are dominated by ligand-to-metal charge transfer bands from the hydroperoxide or azide anions, but otherwise they are similar to those of the synthetic complexes (Rgure 2) (38). The d-d transitions observed at 700 and KXX) nm are more intense than usually observed for high-spin iron(llI) complexes, probably due to the strong antiferromagnetic coupling interaction (38,40). 

The other simple peptide complex e.g. [Fe(Z-Cys-Ala-OMe)4]2- did not exhibit such a reversible redox couple under similar conditions. The Fe(lll) complexes of simple peptide thiolates or cysteine alkyl esters are found to be thermally quite unstable and decompose by oxidaticxi at the thiolate ligand by intramolecular electron transfer. Thus the macro-ring chelation of the Cys-Pro-Leu-Cys ligand appears to stabilize the Fe(in) state. The stability of the Fe(ni) form as indicated by the cyclic voltamnoogram measurements and by the visible spectra of the Fe(in) peptide complexes suggests that the peptide prevents thermal and hydrolytic decomposition of the Fe-S bond because of the hydrophobicity and steric bulk of the Pro and Leu residues (3,4). 

Group VI Donors. Oxygen donor ligands. A new and more successful preparation of CIS- and tra s-K[Rh(ox)2(H20)2] has been reported, via the chromatographic separation of the acid hydrolysis products from Kj[Rh(ox)3],4j-H20. The u.v.-visible spectra of these complexes cast doubts on the purity of the samples previously described. An interesting feature of Rh -oxalate chemistry is the assertion that K3[Rh(ox)3],4 H20 actually exists as the partly unidentate K6[Rh(ox)3][Rh(ox)2(C204H)(OH)],8H20. This has now... 

Banks and Barnum (18) have found that the visible spectra of a series of these nickel and palladium ric-dioxime complexes always show a band in... 

The theory needed to explain why normally diamagnetic compounds should develop singlet and triplet states of very nearly equal energy has been developed by Maki (139-161) Ballhausen and Liehr have come to similar conclusions on much simpler grounds (11). Maki (159) has used purely electrostatic models to determine the splittings of the states of a nickel(II) ion in different symmetries. The results obtained have been tested by attempting to assign the near infrared and visible spectra of suitable complexes with them (160, 161). 

Fig. 7. Visible spectra of the Cu complex of poly(4-vinylpyridine) (a) and of pyridine (b)42,43 and ESR spectra of the Cu complex of poly(4-vinylpyridine) (c) and of pyridine (d)44,4S)...

Figure 7 Ultraviolet-visible absorption spectra of complexes 22 and 37 in ethanol solution at room temperature.

The products of reduction of Fe(NCS)2+ by Cr2+ in aqueous solution containing thiocyanate ions (equation 36), include the isomers of [Cr(NCS)(SCN)(H20)4]+, which contains both bland S-bonded thiocyanate ligands.641 These isomers undergo spontaneous decomposition by parallel aquation (loss of the S-thiocyanato ligand) and isomerization (Cr—SCN— Cr—NCS) reactions. Details of the solution visible spectra of these isomers as well as those of similar chromium(III) complexes for comparison are listed in Table 68. From the compiled data it is apparent that the S-bonded thiocyanate ligand lies very close to Br- in the spectrochemical series while the N-bonded form lies between Nj and NO. 

Table 68 Visible Spectra of Isomeric Thiocyanato and other Chromium(III) Complexes ...

Eu—N distances were 2.57-2.62 A, while the Pr—N distances were 2.63-2.64 A, with Pr—Cl at 2.88 A and Pr—O at 2.48-2.54 A. The visible spectra of the monoterpyridyl complexes have been used to investigate the nephelauxetic effect arising from the M—N bonds.148... 

---