Phosphine-Stabilized Pnictinidenes

Abstract

The reaction of the intramolecular germylene-phosphine Lewis pair (o-PPh2)C6H4GeAr* (1) with Group 15 element trichlorides ECl3 (E=P, As, Sb) was investigated. After oxidative addition, the resulting compounds (o-PPh2)C6H4(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)C6H4(Ar*)Ge(Cl)P (5), arsinidene (o-PPh2)C6H4(Ar*)Ge(Cl)As (6) and stibinidene (o-PPh2)C6H4(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)C6H4(Ar*)GeP] [B(C6H3(CF3)2)4] (8) was isolated. The 31P NMR data of the germaphosphene were compared with literature examples and analyzed by quantum chemical calculations. The phosphinidene was treated with [iBu2AlH]2, and the product of an Al−H addition to the low-valent phosphorus atom (o-PPh2)C6H4(Ar*)Ge(H)P(H)Al(C4H9)2 (9) was characterized.