Phosphido-borane-supported stannates.

The reactions between SnCl and three equivalents of the alkali metal phosphido-borane complexes [RP(BH)]M yield the corresponding tris(phosphido-borane)stannate complexes [LM{RP(BH)}Sn] [R = iPr, LM = (THF)Li (2Li), (EtO)Na (2Na), (EtO)K (2K); R = Ph, LM = (THF)Li (3Li), (THF)(EtO)Na (3Na), (THF)(EtO)K (3K); R = iPrPh, LM = (THF)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 their BH 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.