Syntheses and structures of dimeric sodium and potassium complexes of 2,6-diisopropyl-Anilidophosphine borane ligand

We report here the syntheses and structural studies of dimeric sodium and potassium complexes of composition [Na(THF)2{Ph2P(BH3)N(2,6- i Pr2C6H6)}]2 (2) and [K(THF)2{Ph2P(BH3)N(2,6- i Pr2C6H6)}]2 (3). The sodium complex 2 was readily prepared by the reaction of sodium bis(trimethylsilyl)amide with 2,6-diisopropylanilidophosphine-borane ligand [2,6- i Pr2C6H3NHP(BH3)Ph2] (1-H) at ambient temperature. The potassium complex 3 was prepared by two synthetic routes: in the first method, the ligand 1-H was made to react with potassium hydride at room temperature to afford the corresponding potassium complex. The potassium bis(trimethylsilyl)amides were made to react with protic ligand 1-H in the second method to eliminate the volatile bis(trimethyl)silyl amine. Solid-state structures of both the new complexes were established by single crystal X-ray diffraction analysis. In the molecular structures of complexes 2, the sodium metal is coordinated by the anilido nitrogen (η 1) and borane group (η 1) attached to the phosphorus atom of ligand 1. In contrast, for compound 2, ligand 1 displays η 6 π-arene interaction from 2,6-diisopopylphenyl ring with potassium atom along with η 3 interaction of BH3 group due to larger ionic radius of potassium ion