Substituent Effects on the Structures of Alkali Metal Phosphido‐Borane Complexes

Abstract

Metalation of tBu 2 PH(BH 3 ) (1H), iPr 2 PH(BH 3 ) (2H), iPrPhPH(BH 3 ) (3H), Ph 2 PH(BH 3 ) (4H) or (Mes) 2 PH(BH 3 ) (5H) with one equivalent of nBuLi in either diethyl ether or THF gave the corresponding phosphido-borane complexes, which were obtained as single crystals of the solvates [{tBu 2 P(BH 3 )}Li, and [{(Mes) 2 P(BH 3 )}Li(THF) 2 ] 2 (5Li) after crystallization from diethyl ether; the alternative adduct [{Ph 2 P(BH 3 )} Li(TMEDA)] ∞ (4Li(TMEDA)) was isolated from the reaction of 4Li with TMEDA. Similar metalation reactions between 1H, 2H or 4H and PhCH 2 Na gave the complexes [{tBu 2 P(BH 3 )}Na(THF)] ∞ (1Na) and [{iPr 2 P(BH 3 )}Na(THF)] ∞ (2Na), and [{Ph 2 P(BH 3 )}Na-(TMEDA)(THF)] ∞ (4Na(TMEDA)). Compounds 1Li, 2Li, 3Li, 4Li and 4Li(TMEDA) crystallize as zig-zag polymers, while 5Li crystallizes as a centrosymmetric dimer; compounds 1Na and 2Na crystallize as ribbon polymers, although these differ significantly in structure, while 4Na(TMEDA) crystallizes as a zig-zag polymer.

Phosphido-borane-supported stannates

“…1,2 However, in spite of this, and the relatively simple synthesis of phosphido-borane ligands, they have received only limited attention. 3 While the majority of reported phosphido-borane complexes are of the hard alkali or alkaline earth metals, 4,5 a small number of late transition metal complexes have been isolated; 6 only a very few complexes of these ligands with p-block elements are known. 4 a ,7,8…”