Phosphido-borane-supported stannates

The reactions between SnCl2 and three equivalents of the alkali metal phosphido-borane complexes [R2P(BH3)]M yield the corresponding tris(phosphido-borane)stannate complexes [LnM{R2P(BH3)}(3)Sn] [R-2 = iPr(2), LnM = (THF)(3)Li (2Li), (Et2O)Na (2Na), (Et2O)K (2K); R-2 = Ph-2, LnM = (THF)Li (3Li), (THF)(Et2O)Na (3Na), (THF)(Et2O)K (3K); R-2 = iPrPh, LnM = (THF)(4)Li (4Li)]. In each case X-ray crystallography reveals an anion consisting of a trigonal pyramidal tin centre coordinated by the P atoms of the phosphido-borane ligands. These tris(phosphido-borane)stannate anions coordinate to the alkali metal cations via their BH3 hydrogen atoms in a variety of modes to give monomers, dimers, and polymers, depending on the alkali metal and the substituents at the phosphorus centres. In contrast, reactions between SnCl2 and three equivalents of [tBu(2)P(BH3)]M (M = Li, Na) gave the known hydride [M{tBu(2)P(BH3)}(2)SnH], according to multinuclear NMR spectroscopy.

Automated summary

The reactions between SnCl2 and alkali metal phosphido-borane complexes produce tris(phosphido-borane)stannate complexes. Crystallography confirms an anion with a trigonal pyramidal tin center coordinated by the P atoms of the ligands. These anions coordinate to alkali metal cations via their BH3 hydrogen atoms, forming monomers, dimers, and polymers depending on the alkali metal and phosphorus substituents. In contrast, reactions with [tBu(2)P(BH3)]M (M = Li, Na) yield the known hydride [M{tBu(2)P(BH3)}(2)SnH] according to NMR spectroscopy.