Vanadyl geochemistry

Treibs isolated the first porphyrin coordination complex from a Swiss marl,265 and showed that it (or at least a structurally related derivative) occurred in a wide variety of sedimentary rocks and asphalts. He showed it to contain vanadium and subsequently the involvement of the vanadyl ion was proved.266 Treibs also described a second chelate from the same original source, which he proposed to be an iron complex. Somewhat later it was shown that the complex contained the Ni" ion. It is thus appropriate, and in view of much of the foregoing discussion, to focus attention on the detailed structure of the few fully characterized geoporphyrin complexes recently reported, since their elucidation crowns some five decades of intense activity in this area of coordination geochemistry. 

Yen, T. F. "Electron Spin Resoncince of Vanadyl Porphyrins and other Chelates," Gordon Research Conferences on Geochemistry, Plymouth, New Hampshire, Aug, 31, 1970. 

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