Formation and Rearrangement of Sn II Phosphanediide Cages

The room‐temperature reactions of Sn(NMe 2 ) 2 with less sterically demanding primary phosphines (RPH 2 ) give the homoleptic phosphanediide compounds [SnPR] n in high yields (R= t Bu ( 1 a ), cyclohexyl ( 1 b ), 1‐adamantyl ( 1 c )). However, the room‐temperature reaction of Mes*PH 2 (Mes*=2,4,6‐ t Bu 3 C 6 H 2 ) with Sn(NMe 2 ) 2 gives the model intermediate [{SnPMes*} 2 (μ‐NMe 2 )SnP(H)Mes*] ( 3 ), together with the product of complete deprotonation [SnPMes*] 3 ( 4 ). Phosphorusphosphorus bonded products are produced in these reactions at elevated temperatures. If the reaction producing 1 a is heated to reflux then [ t BuP(H)P(H) t Bu] is produced as the major product (together with tin metal). The novel octanuclear cage [{SnP t Bu} 7 Sn(P t Bu) 3 ] ( 2 ) can also be isolated in low yield, resulting from formal addition of the heterocyclic stannylene [( t BuP) 3 Sn] to a SnP single bond of the intact structure of 1 a . Prolonged heating of the reaction producing 3 and 4 leads to the formation of the diphosphene [PMes*] 2 ( 5 ) and tin metal. The X‐ray structures of the heptamer 1 a ( n =7), octanuclear 2 and trinuclear 3 are reported.