Tris carbonyl

Fig. 7. Representive stmctures for compounds of molybdenum(0) (a) Mo(CO)g (b) tris(acetonitrile)tris(carbonyl)molybdenum(0) (c) bis(l,2-diphenylphosphinoethane) bis (dinitrogen) molybdenum(0), [R2PCH2CH2PR2]2Mo(N2)2, where R = CgH, also known as Mo(dppe)2(N2)2, where dppe = 1,2 — diphenylphosphinoethane (d) cyclopentadienyl tricarbonyl molybdenum(0) anion, CpMo(CO)3, where Cp = cyclopentadienyl (e)...

Among the many syntheses of caspanospermine, worthy of note is that reported in Fig. 46, in which the insertion of the nitrogen and the formation of both cycles occurs one-pot by reductive amination of a tri-carbonyl... 

Abb. 1. Newnian-Projektionsiormeln fiir Athan (A), Fcrroccn (B), Cyclo-pentadienyl-Mangan-tiicarbonyl (Cymantren) (C) und Benzol-Chrom-tri-carbonyl (D). Bei den Metallocenen wurde auf die VViedcrgabe des Metalls... 

Cyclopeniadienyl-dimethoxy-ferryl)-lelrafluoro-l-trimethyl-silyl- Xlll/9a, 376 [4-SiR3 —C6F + (OC)jFe —R] 3(or 4)-(t)5-Cyclopentadicny]-tri-carbonyl-wolfro)-1 -fluoro-XIII/7, 513 [Ar2l" + R-W(CO),] (t 5-Cyclopentadicnyl-triplicnylphos-phan-nickclo)-pcntafluoro-XIII/9b. 670 (LL NiCl + Ar-MgX)... 

As already mentioned, no [6 + 4] cycloaddition is observed when tri-carbonyl-i 6-l,3,5-cycloheptatrienemolybdenum(0) is irradiated in presence of conjugated dienes. So an explanation of these experimental results has to be provided. One reason might be an unfavorable fit of the CuH14 n(CH3 ) and C, 4H18 - (CH3) hydrocarbons into the coordination sphere of molybdenum, arising from the increased Mo—C bond lengths. The other reason concerns the possible different stabilities of the intermediates of the photochemical [6 + 4] cycloaddition with molybdenum as the central metal. 

When they are sufficiently low, the pAa (pA p values of carbonyl compounds (corresponding to enolate formation) in water can be obtained directly from pH measurements of partly neutralised compounds or by spectroscopic determination of the ratio of the ionised and unionised forms in weakly basic media. Indeed, most of the acidity constants of di- or tri-carbonyl compounds have been determined by these methods. However, such direct determinations are not valid for monocarbonyl compounds for which the pA values are known to be usually higher than that of water. For these very weak acids the competitive and acidity function approaches have been used, although both have serious limitations. 

Fig. 4. IR spectra of CO dosed, at liquid-nitrogen temperature, onto Cu -ZSM-5 (bottom dotted lines), Cu -mordenite (bottom full lines), Cu -P (top dotted lines), and Cu -Y (top full lines) zeolites. Parts (a), (b), and (c) report low, medium, and high Pco spectra, respectively, approximately corresponding to mono-, di- and tri-carbonyl complexes. (Adapted with permission from Bordiga et al. (P5).)...

The presence of cations in the less accessible side pocket sites of mordenite implies the co-presence of mono-, di-, and tri-carbonyl adducts even at the higher values of Pco (94), resulting in a broader and rather unresolved IR spectrum (Fig. 4c, bottom full line). In zeolite Y, notwithstanding the presence of two cationic sites in the supercage, the IR spectrum obtained at high Pco indicates the presence of only one family of Cu -(CO)3 adducts. This observation is explained by the strong solvating power of the CO molecules, which are able to extract the Cu ions from the more shielded position (site IP), as demonstrated by both EXAFS (76,77,97) and XRPD data (93). The experiments reported in Fig. 4 indicates that... 

Tetracarbonyl cations [Cr(CO)4(L2)]+, where L2 represents arylphosphines, alkyl, or aryl phosphites, or a bidentate ligand with phosphorus or arsenic donor atoms, have been produced by both chemical and electrochemical means. However, oifly one of these complexes, namely, tra i -[Cr(CO)4(PPh3)2]+, is stable enough to be isolated as the perchlorate salt. Exposure to light and moisture produces tra i -Cr(CO)4(PPh3)2 via disproportionation. Just as easily isolated, but somewhat less sensitive, are the [Cr(CO)3(PR3)3]+ cations. " Oxidation with a silver ion or NO+ converts the /uc-(R3 = Me2Ph, (OMe)3) and mer-(R3 = (OMe)3, (OMe)2Ph, (OPh)3) complexes into Cr products with mer structures. Light and heat promote the formation of reduced wer-Cr(CO)3 (PR3)3. These tetra(carbonyl) and tri(carbonyl) cations have been the subject of ESR spectroscopy and theoretical study. 

Wolfram ( )5-Cyclopentadienyl)-(dichlor-methyl-silyl)-tri-carbonyl- XIII/5, 286... 

Ruthenium (3-5-if3-2-Deuterio-5-dehydro-cycloheptenyl)-tri-carbonyl- XIII/9a, 555... 

Wolfram (> 5-Cyclopentadienyl)-(heptafluor-butanoyl)-tri-carbonyl- XIII/7, 505 f. 

Chrom (i/6-4,5-Diethyl-l, 2,3,6-tetra-methyl-l,2,3,6-diazadiborin)-tri-carbonyl- XIII/3c, 75... 

Other studies of considerable interest have been performed on such systems 33, 57). Pettit et al. (30) had first suggested that the chromium tri-carbonyl-complexed benzyl cation was extraordinarily stable. Trahanovsky and Wells (80) have quantitatively estimated the difference of pK + for... 

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