Phosphine-Stabilized Pnictinidenes.

The reaction of the intramolecular germylene-phosphine Lewis pair (o-PPh2 )C6 H4 GeAr* (1) with Group 15 element trichlorides ECl3 (E=P, As, Sb) was investigated. After oxidative addition, the resulting compounds (o-PPh2 )C6 H4 (Ar*)Ge(Cl)ECl2 (2: E=P, 3: E=As, 4: E=Sb) were reduced by using sodium metal or LiHBEt3 . The molecular structures of the phosphine-stabilized phosphinidene (o-PPh2 )C6 H4 (Ar*)Ge(Cl)P (5), arsinidene (o-PPh2 )C6 H4 (Ar*)Ge(Cl)As (6) and stibinidene (o-PPh2 )C6 H4 (Ar*)Ge(Cl)Sb (7) are presented; they feature a two-coordinate low-valent Group 15 element. After chloride abstraction, a cyclic germaphosphene [(o-PPh2 )C6 H4 (Ar*)GeP] [B(C6 H3 (CF3 )2 )4 ] (8) was isolated. The 31 P NMR data of the germaphosphene were compared with literature examples and analyzed by quantum chemical calculations. The phosphinidene was treated with [iBu2 AlH]2 , and the product of an Al-H addition to the low-valent phosphorus atom (o-PPh2 )C6 H4 (Ar*)Ge(H)P(H)Al(C4 H9 )2 (9) was characterized.