| http://www.w3.org/ns/prov#value | - The precursor may be a chemical compound of the formula: AR1R2X wherein A is selected from phosphorous or boron, X is a halogen or halogen containing compound and R1 is selected from halogens, alkyl groups having from 1 to 20 carbons, alkoxy groups containing 1 to 20 carbons, or aromatic groups having from 1 to 20 carbons, R2 is selected from halogens, alkyl groups having from 1 to 20 carbons, alk
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