a sulfur-carbon bond and a phosphorus-halide bond. Such a compound could act as an acetylcholinesterase inhibitor in insects, but in order to make a better insecticide it would be best to convert the halide to another leaving group which would form a less water sensitive product. For instance the reaction of para-nitrophenolate would form a compound similar to parathion. Lawesson's reagent has been used as a starting material for a herbicide by reaction with a 1-alkoxy-2,3-dihydroxy propane. This formed a compound which could be used to kill plants. This reaction of a 1,2-diol with lawesson's reagent results in a symmetric breaking of the PS ring, both halves of the lawesson's reagent end up being converted to the same product. A different type of ring breaking reaction can occur when Lawesson's reagent is reacted with a metal compounds such as a platinum dichloride bis-phosphine complex, in this case one molecule of MeOCHP(S)Cl is formed as a side product to the platinum complex ([Pt(SP(S)CHOMe)(PR)]). Lawesson's reagent can be used as a dehydrating reagent, for example it has been used to convert a β-aminoamide into an imidazoline. Another useful reaction of Lawesson's reagent is the conversion of a 1,4-diketone into a thiophene ring, this reaction can be done with PS but a much higher temperature would be required to make it work with PS. It was claimed in a German patent that the reaction of 1,3,2,4-dithiadiphosphetane 2,4-disulfides with dialkyl cyanamides formed plant protection agents which contained six-membered (P-N=C-N=C-S-) rings. It has been proven in recent times by the reaction of diferrocenyl 1,3,2,4-dithiadiphosphetane 2,4-disulfide (and Lawesson's reagent) with dimethyl cyanamide that in fact a mixture of several different phosphorus containing compounds is formed. Depending on the concentration of the dimethyl cyanamide in the reaction mixture either a different six membered ring compound (P-N=C-S-C=N-) or a non-heterocylic compound (FcP(S)(NR)(NCS)) is formed as the major product, the other compound is formed as a minor product. In addition small traces of other compounds are also formed in the reaction. It is unlikely that the ring compound (P-N=C-S-C=N-) {or its isomer} would act as a plant protection agent, but (FcP(S)(NR)(NCS)) compounds can act as nerve poisons in insects. These compounds bearing terminal sulfur atoms on the phosphorus atom are much less toxic than the compounds (such as sarin, VX and tetraethyl pyrophosphate) which have an oxygen in place of this terminal sulfur. This is because the P=S compound