CHEMICAL EXCHANGE IN VIRTUALLY COUPLED SYSTEMS . METAL-ION-INDUCED RELAXATION OF METHYL-PHOSPHORUS COUPLING IN PHOSPHINE COMPLEXES

Theoretical evidence is presented to show that AX coupling may be relaxed by chemical exchange in A′AX systems if A and A′ are strongly coupled. Analysis shows that one might expect to find chemical situations for methylphosphine complexes where the proton nmr pattern is a doublet, a “virtual-coupled” triplet, or a singlet depending on phosphorus-phosphorus coupling and ligand exchange. We present here some examples of phosphine complexes where A-X decoupling occurs and discuss the various causal mechanisms. © 1969, American Chemical Society. All rights reserved.