Sodium Aminodiboranates Na(H 3 BNR 2 BH 3 ): Structural and Spectroscopic Studies of Steric and Electronic Substituent Effects.

We describe the syntheses of a series of sodium aminodiboranate salts, Na(H 3 B-NR 2 -BH 3 ), with different substituents on nitrogen, including sodium salts of the unsubstituted aminodiboranate, H 3 B-NH 2 -BH 3 - , and of the N-substituted anions H 3 B-NRR'-BH 3 - , where NRR' = NHMe, NHEt, NH(SiMe 3 ), NEt 2 , N( i -Pr) 2 , N(SiMe 3 ) 2 , NMe( i -Pr), NMe( t -Bu), NMe(SiMe 3 ), and the pyrrolidide and piperidide derivatives NC 4 H 8 , NC 5 H 10 , and NC 5 H 8 - cis -2,6-Me 2 . The compounds have been characterized by 1 H and 11 B NMR spectroscopy and IR spectroscopy; crystallographic studies have been carried out for the unsolvated N , N -dimethylaminodiboranate salt Na(H 3 B-NMe 2 -BH 3 ) and several sodium aminodiboranate salts in which the sodium ions are solvated with ethers (dioxane, diglyme, tetrahydrofuran, and 12-crown-4) or amines ( N , N , N ', N '-tetramethylethylenediamine). One of the structures contains a rare example of an ether ligand in which one oxygen atom bridges between two metal ions. General structural and spectroscopic trends as a function of the substituents on nitrogen are discussed.