Boron Hydride Fragments as Coordinating Ligands

Abstract

The diammoniate of borane carbonyl was first prepared by BURG and SCHLESINGER in 1937 (1). Using chemical and spectroscopic methods CARTER and PARRY (2) showed that the closely related bis -methylamine adduct of borane carbonyl is a methyl ammonium salt of a new N -methyl borano -carb — am ate anion:

NORDMAN (3) confirmed the above structure by a single crystal X-ray diffraction study. All atoms in the anion are essentially planar. The key distances are C-N 1, 45 Å; C=O 1,28 Å; C-B 1, 60 Å; the angle C-N-C in the anion is 125, 5°. If one considers that the oxyacids are coordination compounds in which oxygen atoms serve as ligands coordinated around a central atom, then the boranocarbamate anion represents a carbamate ion in which one coordinated oxygen atom is replaced by a BH₃ group. Using this model, a series of new oxyacid analogues can be visualized. Several members of the series have been prepared. The carbonate analogue is of interest.