Mossbauer data complex

Table 3. Mossbauer data of iron silylene complexes (Fe as standard)...

Acetyl migration occurs in the reaction of Tl(MeCOCHCOMe) with Pms Pd(PhCN)2Cl2, which yields an A-acetyl-jS-ketoimine chelate (17).471 Mossbauer data indicate that Sn(MeCOCHCOMe)2 has a trigonal pyramidal geometry with one oxygen atom from each acetylacetonate ligand in an axial position.472 The equatorial lone electron pair is both stereochemically and chemically active. Complexes in which the metal acts as the donor rather than the acceptor are formed by photolysis of Sn(MeCOCHCOMe)2 and Group VI metal hexacarbonyls in THF. The products, Sn(MeCOCHCOMe)2M(CO)5 (M = Cr, Mo, W), evidently contain tin-metal bonds. The low... 

In the case of Fe(OEC)Py susceptibility measurements indicated a S = 3/2 ground state for the metal atom (p = 3.80 BM) but this characterization is not in agreement with Mossbauer data (8Fe = — 0.09 mms 1, AEq = 3.88 mms"1) which correspond rather to those observed for the Fe4+ complexes. The hypothesis has been considered that the complex would be an Fe4+ corrole anion radical the magnetic properties (S = 3/2) of which would result from ferromagnetic spin coupling of Fe4+ (S = 1) with a macrocycle anion radical (S = 1/2) [27]. Theoretical studies are necessary to completely characterize the electron distribution in the complex. 

The preceding results for the trimethyltin chloride-pyridine complex (68) fit well with IR (8, 9) and Mossbauer data (1,101). The rs(Sn—C) ras(Sn—C) intensities ratio (Table XII) suggests a planar arrangement of the methyl groups, whereas r(Sn—Cl) suggests that the bond polarity is markedly higher than in uncomplexed Me3SnCl. 

Tin Mossbauer. 119Sn Mossbauer data also provide a bulk diagnostic and this method has been utilized in a number of studies (for example, 7,26-39). Direct evidence for PtSn alloy formation was obtained from Mossbauer studies (for example, 7,34,35,38,39) however, many of these studies were at high metal loadings and even then a complex spectrum was obtained so that there was some uncertainty in assigning Sn(0) to the exclusion of tin oxide phases. 

Tin-119 Mossbauer data have been reported for a number of stannylene complexes and are collected in Table VI. The IS (isomer shift) of the stan-nocene complexes is much lower than that of stannocene, while the QS (quadrupole splitting) is much higher. This has been interpreted as indicating synergistic cr- plus 7r-bonding of the stannylene to the transition metal (52). 

Iron-57 Mossbauer data have been reported for the complexes [Cp2SnFe(CO)4]2 and Cp2Sn(py)Fe(CO)4. The IS values are similar to those for the LFe(CO)4 complexes, L = Co, PPh3, P(OEt)3, and on this... 

Tin-119 Mossbauer Data for Transition Metal Stannylene Complexes... 

Table 16 Mossbauer Data for Complexes of the Type [Fe(LL) X, ] (LL = phen, bipy) Displaying Anomalous Temperature...

Thus, x-ray powder diffraction, electron paramagnetic resonance, luminescence and Mossbauer data suggest that a complex of Sn, V0+ and oxygen forms that leads to the passivation of vanadium when deposited on the zeolite, and on zeolite/gel mixtures. This complex may be a compound like VpSnO, or similar higher molecular weight species. Evidence of Sn/V all oy formation has not been found from Mossbauer spectroscopy. 

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