PHOSPHORUS-SUBSTITUTED N,N'-DIMETHYLTHIOUREA COMPOUNDS .2. SYMMETRICALLY BISPHOSPHORYLATED DERIVATIVES

The symmetrical N,N'-diphosphorus(III)-substituted derivatives 2-4 were obtained in the reaction of N,N'-dimethyl thiourea, 1 with the appropriate phosphorus(III) chlorine compound in the presence of an HCl acceptor, An X-ray structure analysis of compound 2 [C2/c, a = 1646.1 pm, b = 948.1 pm, c = 1731.4 pm, beta = 115.86-degrees, R = 0.0361 shows that the molecule possesses crystallographic twofold symmetry along the C-S bond. The nonbonding phosphorus-phosphorus distance is 290 pm. In the reaction of the mono-(i)Pr2P(III)-substituted derivative of thiourea, 5 with further diisopropyl-chlorophosphine, the S-substituted isomer, 6 (see part I of this series) was formed initially. Subsequently, in a second step, compound 6, at -20-degrees-C, underwent transformation into N,N'-bis(di-isopropylamino)-N,N'-dimethyl thiourea, 7. An attempt at the synthesis of the bis(di-tert.-butylphosphino)-derivative, 9 was unsuccessful.