Solutions, IR spectra

The cis-structure (like [Rh(CO)2Cl]2 folded, with an angle of 123°) has been confirmed for PMe2Ph (X-ray) whereas the P(NMe2)3 analogue is trans (IR). Comparison of solid-state and solution IR spectra indicates that both isomers are present in solution (PR3 = PMe3, PMe2Ph, P(NMe2)3) [64],... 

Y3Fe50i2 [7], These complexes have been obtained at 110-120°C, isolated, and studied in the crystalline form and in an aqueous solution. IR spectra suggest that these are monodentate coordinated to the metal ions. NMR data are in accord with an assumption that hydroxy and carboxylate groups attached to the central carbon atom of the citric acid anion are coordinated to the metal cations forming a stable five-membered ring. However, these important data are obtained at conditions that do not correspond to the conditions of the synthesis of precursors. 

Table 1 Solid-state and solution IR spectra of Co(CO)4 salts."...

In order to know the structure in solution, IR spectra were compared both in solution (benzene solution) and in the solid (Nujol mull). The close similarity between these spectra indicates that the structure in solution is identical to that in crystal. 

Prototropy in hydroxybenzopyranones has been investigated. The hydroxychromone (241) does not undergo tautomerism to the dione (242 equation 7). The NMR spectrum of a CDC13 solution shows the methyl signal at S 2.50 and since this appears as a singlet, it would seem that the contribution of (242) is not significant. Solid state and chloroform solution IR spectra also support this conclusion (71MI22201). 

Solution IR spectra recorded on a Perkin Elmer 597 spectrophotometer. 

Solution IR spectra from CHCI3 solutions were obtained with a Nicolet 20 DX-B spectrometer. 6NMR spectra were obtained with a home-built 250-MHz NMR spectrometer. c Chemical shifts are parts per million downfield from 85% phosphoric acid. 

Other reports confirm similar reaction of C02 with metal alkoxide compounds. Benzene solutions of the alkoxide compounds Ti(OBu")4, Zr(OBu")4, Zr(OEt)4, Nb(OEt)5, and Fe(OEt)3 were found to absorb carbon dioxide in various amounts (151). Only Zr(OBu")4 reacted with an amount approaching one equivalent per metal complex. The solution ir spectra indicate formation of coordinated organic carbonates. From this evidence, equilibrium formation of the species M(0R) 1(02C0R) under 1 atm of C02 is inferred. 

Take solution IR spectra of VO(acac)2 in methylene chloride (CH2CI2), acetonitrile (CH3CN), and pyridine using 0.2 mm NaCl solution cells. 

Note. Weak peaks at higher frequency may not appear in solution IR spectra due to limited solubility. 

Solution IR spectra recorded on a Perkin Elmer S97 spectrophotometer, k sipjiH mmR spectra were recorded on a Broker WM 250 at 101.26 MHz in CDjCOCDs at 263 K. Chemical shifts are in parts per million downfield from external 85% H3PO4 in DjO. 

Solution IR spectra from CHCI3 solutions were obtained with a Nicolet 20 DX-B spectrometer. 

The polymer structures were verified by infrared and proton NMR analysis. Films for infrared (IR) analysis were cast onto KBr discs from THF/CHCI3 solutions. IR spectra were recorded on a Nicolet FT-IR. Proton NMR were recorded on an EM 360 60 MHz spectrometer. 

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