The Transmission of Substituent Effects in Transition Metal Complexes

1971 ◽  
Vol 49 (1) ◽  
pp. 56-66 ◽  
Author(s):  
D. R. Eaton ◽  
K. L. Chua
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Charge Transfer ◽  
Magnetic Resonance ◽  
Transition Metal ◽  
Transition Metal Complexes ◽  
Opposite Effect ◽  
Substituent Effects ◽  
Ligand Substitution ◽  
Simple Interpretation ◽  
Ligand Charge Transfer

The effect of ligand substitution on bonding to other ligands has been investigated in a series of V(III) complexes. Nuclear magnetic resonance (n.m.r.) contact shifts have been utilized for this purpose. These shifts are interpreted as arising from metal to ligand charge transfer. The results obtained are contrary to those expected from simple considerations of the electron withdrawing or donating abilities of the substituents. Electron withdrawing substituents decrease the charge transfer to the substituted ligand and increase the charge transfer to the remaining ligands. Electron donating substituents have the opposite effect. A simple interpretation is proposed to account for these results. An electron withdrawing substituent on a ligand in the xy plane increases the occupancy of dxy which cannot interact with the π system of the ligand in the xy plane but which is available for π bonding with the remaining ligands. Effects of this type are to be anticipated whenever the filling of the t2g orbitals is not symmetrical.

Transition metal complexes of substituted alkynes. II. Pentafluorophenylacetylene complexes of iron and cobalt

1968 ◽  
Vol 21 (1) ◽  
pp. 97 ◽  
Author(s):  
RS Dickson ◽  
DBW Yawney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Cobalt Complexes ◽  
Spectroscopic Properties ◽  
Stable Complex ◽  
Structural Isomers ◽  
Nuclear Magnetic Resonance Spectra

Treatment of pentacarbonyliron with pentafluorophenylacetylene has given the stable complex tricarbonyl-2,5-bis(pentafluorophenyl)cyclopentadienoneiron. There is no evidence of the formation of other structural isomers. The complex is also formed from pentafluorophenylaoetylene and nonacarbonyldiiron or dodecacarbonyltriiron. Two alkyne-cobalt complexes have been isolated from the interaction of octacarbonyldicobalt and pentafluorophenylacetylene. One of these is a bridging alkyne complex of molecular stoicheiometry Co2(CO)6(C6F6CCH); the second is a complex of formula Co3(CO)9(CCH2C6F5). The infrared and nuclear magnetic resonance spectra of the complexes are given, and the probable structures of the compounds are deduced from these spectroscopic properties.

Transition metal complexes of substituted alkynes. IV. Some bridging alkynecobalt complexes

1969 ◽  
Vol 22 (3) ◽  
pp. 533 ◽  
Author(s):  
RS Dickson ◽  
DBW Yawney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Spectroscopic Properties ◽  
Terminal Alkynes ◽  
Nuclear Magnetic Resonance Spectra ◽  
Direct Formation ◽  
Formation Of Complexes

Two new organocobalt complexes, Co2(CO)4(CF3C2CF3)3 and Co2(CO)4(CF3C3H)2- CF3C2CF3, have been isolated from the appropriate reactions of hexafluorobut-2-yne with octacarbonyldicobalt and of 3,3,3- trifluoropropyne with μ-hexafluorobut-2-yne-hexacarbonyldicobalt. The probable structures of these compounds are discussed in light of their infrared and nuclear magnetic resonance spectra. ��� The direct formation of complexes of the type Co3(CO)9CCH2R has been established in the reactions of several terminal alkynes, RC2H (R = H, CF3, C6H5), with octacarbonyldicobalt. The spectroscopic properties of the products so obtained are given.

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