Stannylene and germylene as powerful dechlorinated reagents : new route to diphosphene

Dichlorophosphines RPCl2 [R=Cl ( ), Ph ( ) and 2,4,6-But3C6H2 ( ] are reduced to the corresponding phosphorus-I compounds by the stannylene Me2Si (NBut)2Sn: ( ) or by the germylene GeI2 ( ) ; in the case of the reaction of ( ) with ( , bis(2,4,6-tri-tert-butylphenyl)-diphosphene ( ) is obtained with a 65 % yield