Carbonyls chalcogenides

Most of the chalcogenide studies have involved binary, ternary, and pseudo ternary metal clusters. The ternary Chevrel-phases can be represented by MxMo6X8 (M = transition metal, X = chalcogen atom), where the transition metal fills the cavities in the Mo6X8 crystal structure. The pseudo-ternary (or pseudo-binary) Chevrel-phase clusters can be represented by MxMo6 xX8, where the Mo atoms are substituted by transition metal atoms.185 The crystal structure of ternary and pseudo ternary Chevrel phases are shown in Fig. 4. The carbonyl-chalcogenide clusters189 192 will be discussed in the next section. 

Pentacarbonyliron(O) is obtained by carbonylation of anhydrous FeE under drastic conditions (200 °C, 200 atm of CO pressure) in the presence of copper as halogen acceptor. This is consistent with the observation that iodo-carbonyls of group 11 metals (Cu, Ag, Au) are unstable with respect to the corresponding metal iodides, and no contamination from other carbonyl products can occur from the use of copper. The yields of Fe(CO)s are essentially quantitative considerably lower yields are obtained with FeCls (1%) or FeBrs (20%). Pentacarbonyliron(O) can also be obtained from finely divided iron at 200 °C under pressure (200 atm) of CO, especially in the presence of chalcogens (sulfur or selenium) as promoters. In the presence of sulfur (0.3at.%), an excellent yield of Fe(CO)s (94%) is obtained selenium (0.3at.% 93% yield) and tellurium (1 at.% 89% yield) are equally good under comparable conditions. Probably iron-carbonyl chalcogenides are formed as intermediates. Some compounds of this type have been reported by independent syntheses and have also been structurally characterized. 

Carbonyls. Related to the chalcogenide and metal cluster studies are the carbonyl studies for ORR.189 I92-198-201 The majority of the carbonyl work has been reported by several Mexican research groups. This body of work appears to have developed from studies on ruthenium-containing chalcogenide catalysts in the mid-1990 s. The precursors used for these catalysts involved Ru-carbonyls.202... 

NMR spectra, 20 347 structural parameters, 20 297, 299 structure of, 20 300 chalcogenide halides, 23 381-382 structure, 23 382 complexes, 6 2 anation reactions, 34 225 with bipy and phen, 12 185-187 5-coordinate, 34 229, 234, 236-238 with divalent tin, 11 119 with germanium, 11 107-108, 112 homoleptic, 2,2 -bipyridine, 34 28-30 with olefins, 12 311-316 sulfoxides, 24 166 carbonylation reactions, 24 143 and catalyzed decomposition of H2O2, 24 150-151... 

FTIR has been mainly used to obtain structural details of films and to monitor intercalation of metal ions into the film structure and the subsequent reactions of the films with dihydrogen chalcogenides. Both transmission (FTIR-T) and reflection-absorbance (FTIR-RA) modes have been utilized. For the most part these studies have involved films of fatty acids with divalent metal ions. The key features of the FTIR spectra of these films include the asymmetric and symmetric stretching modes of the carboxylate group vs(C02-) and va(C02 ), associated with the M2+/carboxylate complex, and the carbonyl stretching mode v(C=0) of the proton-ated fatty acid. The disappearance of the v(C02 ) (1500-1600 cm-1) and appearance of the v(C=0) bands (—1700 cm-1), concurrent with the formation of the metal chalcogenide and regeneration of the fatty acid, have been used to evaluate... 

Heterometal alkoxide precursors, for ceramics, 12, 60-61 Heterometal chalcogenides, synthesis, 12, 62 Heterometal cubanes, as metal-organic precursor, 12, 39 Heterometallic alkenes, with platinum, 8, 639 Heterometallic alkynes, with platinum, models, 8, 650 Heterometallic clusters as heterogeneous catalyst precursors, 12, 767 in homogeneous catalysis, 12, 761 with Ni—M and Ni-C cr-bonded complexes, 8, 115 Heterometallic complexes with arene chromium carbonyls, 5, 259 bridged chromium isonitriles, 5, 274 with cyclopentadienyl hydride niobium moieties, 5, 72 with ruthenium—osmium, overview, 6, 1045—1116 with tungsten carbonyls, 5, 702 Heterometallic dimers, palladium complexes, 8, 210 Heterometallic iron-containing compounds cluster compounds, 6, 331 dinuclear compounds, 6, 319 overview, 6, 319-352... 

Metal carbonyl monoanions, with trivalent Group 13 element halides, 3, 347, 3, 357 Metal carbynes, Fe-containing, 6, 325 Metal-catalyzed cycloadditions, alkenyl- and alkynylboron compounds, 9, 180 Metal cation receptors characteristics, 12, 466 ferrocene-based, 12, 466 Pt- and Au-based receptors, 12, 471 types, 12, 473 Metal chalcogenides... 

---