Carbonyl halides of the Group VI transition metals. XXVII. Carbon-13 N.M.R. studies on molybdenum compounds

1982 ◽  
Vol 35 (5) ◽  
pp. 895 ◽  
Author(s):  
R Colton ◽  
J Kevekordes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Transition Metals ◽  
Carbonyl Group ◽  
High Frequency ◽  
Circumstantial Evidence ◽  
Large Shift ◽  
Group Vi ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

Carbon-13 nuclear magnetic resonance studies have been carried out on a number of molybdenum(II) carbonyl halide species. It has been found that for these seven-coordinate capped octahedral complexes there is a very large shift to high frequency for a carbonyl group in the capping position. Thus carbon-13 n.m.r. provides a useful tool to distinguish between possible isomers. Trends in stability and isomer formation previously suspected from circumstantial evidence can now be rationalized.

13C Nuclear Magnetic Resonance Studies. 47. 13C Spectra of some exo-Methylenecycloalkanes and -norbornanes

1975 ◽  
Vol 53 (4) ◽  
pp. 589-595 ◽  
Author(s):  
S. H. Grover ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Carbonyl Group ◽  
Ring System ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Methylene Group ◽  
Shielding Effects ◽  
Nuclear Magnetic

The shielding effects of the exo-methylene group on neighboring carbons in several cycloalkanes, methylcyclohexanes, and in the norbornane ring system have been characterized by 13C n. m. r. examination of 28 compounds. The results are compared with those for the carbonyl group and the utility of these data for structural elucidations is discussed. The more distinctive trends exhibited by the methyl carbons in these systems are compared with those for cyclohexanes, cyclohexanones, norbornanes, and norcamphors.

scholarly journals Further Nuclear Magnetic Resonance Studies of Flavone

1994 ◽  
Vol 12 (2) ◽  
pp. 85-89 ◽  
Author(s):  
Cirilo García-Martínez ◽  
Martha S. Morales-Rios ◽  
Pedro Joseph-Nathan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Carbonyl Group ◽  
Isotope Shift ◽  
Coupling Constants ◽  
Magnetic Resonance Studies ◽  
Isotope Shifts ◽  
Nuclear Magnetic

The incorporation of 92.7% of13C at the carbonyl group of flavone allowed to measure two- and three-bond carbon-carbon coupling constants which range from 1.4 to 3.5 Hz, and to measure two-, three- and four-bond carbon-hydrogen coupling constants which range from 0.3 to 3.8 Hz. A mixture of unlabelled flavone1with its 4-13C labelled analogue2further allowed to measure one-bond induced isotope shifts of -15.5 and -16.2 ppb for C-3 and C-4a, respectively, and a three bond induced isotope shift of +3.7 ppb for C-I'.

Carbonyl halides of the Group VI transition metals. XIX. Iodocarbonyl complexes of molybdenum and tungsten with Bis(diphenylarsino)methane

1970 ◽  
Vol 23 (3) ◽  
pp. 441 ◽  
Author(s):  
R Colton ◽  
CJ Rix
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carbon Monoxide ◽  
Magnetic Resonance ◽  
Transition Metals ◽  
Direct Interaction ◽  
Acetone Solution ◽  
Group Vi ◽  
First Time ◽  
And Tungsten ◽  
Nuclear Magnetic

Complexes of the general formulae M(CO)3(dam)I2, M(CO)3(dam)2I2, and M(CO)2(dam)2I2 have been prepared and characterized [M = Mo, W; dam = bis(diphenylarsino)methane]. All of the compounds are diamagnetic and non-electrolytes in acetone solution. The tungsten derivatives were prepared by direct interaction of dam with diiodotetracarbonyltungsten(11), but the molybdenum analogues were obtained by iodine oxidation of the zero-valent complex Mo(CO)4(dam)2 whose preparation is reported for the first time in this paper. The bis(dam)tricarbonyl complexes, M(C0)3(dam)2I2, are unstable in solution giving M(CO)2(dam)I2 and free dam in equilibrium with undissociated complex. The bis(dam)tricarbonyl complexes also readily lose carbon monoxide, especially in the case of molybdenum, to give M(CO)z(dam)2I2. These dicarbonyl complexes readily absorb carbon monoxide to re-form the tricarbonyl complexes to give a reversible carbon monoxide carrying system. Overall, these systems may be represented by the general equations : M(CO)3(dam)I2 + dam ↔ M(CO)3(dam)2I2 + CO These equilibria have been studied using both infrared and nuclear magnetic resonance techniques.

Substituted carbonyl derivatives of the Group VI transition metals. V. Complexes with tolyl-substituted Bis(diphenylarsino)methane ligands

1974 ◽  
Vol 27 (2) ◽  
pp. 401 ◽  
Author(s):  
JA Bowden ◽  
R Colton ◽  
Z Sztajer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Transition Metals ◽  
Steric Effects ◽  
Group Vi ◽  
Carbonyl Derivatives ◽  
Derivatives Of ◽  
Nuclear Magnetic

Ligands of the type bis(ditoly1arsino)methane have been synthesized and their derivatives with hexacarbonylmolybdenum(0) prepared. Nuclear magnetic resonance and infrared spectroscopy have been used to determine the stereochemistry of the complexes and also to study steric effects within the molecules.

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