Acetylene diamagnetic anisotropy

Going one step further, we might ask about the influence that a phosphorus multiple bond may have on the chemical shift. From C-NMR, we know that an olefin resonates downfield from an alkane, and an acetylene is found in between, but closer to the alkane. This is explained by diamagnetic anisotropy and the behaviour of P—C, P=C, and I C bonds should be analogous. 

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