Carbonyl mode

Ligand exchange at the metal, while the Si-M bonds remains intact. Two important types of ligand, hydrogen (mode 4b) and carbonyl (mode 4a) are differentiated from the rest (mode 4c). 

The INS spectra of metal carbonyl hydrides [My(CO)zHJ (x,y,z > 1) are dominated by the hydrogen motion. However, this motion is coupled more or less strongly to the carbonyl modes and the result is a rainbow at... 

The spectral series depicted in Fig. 4.18(a) were measured during the hetero-Diels-Alder reaction of the phthalimidobutenone 1 with propenyl methyl ether 2 to yield the diastereomeric dihydropyrans 3 and 4. The transformation is monitored via the carbonyl modes of the phthalimido moiety. It should be noted, however, that the two diastereomers, 3 and 4, cannot be distinguished by the i.r. absorption of these vibrations. The reaction in Scheme... 

All three carbonyls behave similarly towards thoroughly outgassed MgO. Ni(CO)4 and Fe(CO)s show vide infra) similar behaviour. The interaction takes place with ionic pairs Mg O" in low co-ordination giving species of the type (1). The lowering of the symmetry in both the M(C0)6 structures formed on AI2O3 and MgO causes the appearance of new carbonylic modes as expected. Between ambient temperature and 200 °C, dimeric and trimeric species are also formed above 250°C irreversible and complete decarbonylation occurs as also monitored by the... 

In attempts to investigate further the differences in the local environment of BPhL versus BPhj, we have also conducted preliminary RR studies on RCs from Rb. capsulatus wild-type and the (L)E104L mutant. Oxidation-induced frequency shifts of the carbonyl modes are also observed for these RCs. Comparison of the data for RCs from the wild-type and the (L)E104L mutant indicate that hydrogen bond to the (C9=0) group of BPhL partially responsible for the fact that the frequency of the v(C9=0) vibration of BPhL is substantially lower than that of BPhj. In particular, this frequency difference is 25 cm ... 

The observed frequencies of the other acetyl carbonyl and two other keto carbonyl modes in the Rc. gelatinosus P spectrum indicate that no other H-bonds are associated with these carbonyls (see Table I). Thus, the assymetric H-bonding pattern of the C2 acetyl and C9 keto carbonyls of P in Rc. gelatinosus is the same as that of P in Rb. sphaeroides. 

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