A new class of binuclear gallium hydrides:: Synthesis and properties of [{GaCl(hpp)H}2] (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidate)

Herein we report on the synthesis and characterization of the first representative of a new class of gallium hydrides, namely [{GaCl(hpp)H}(2)] (hpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidate). Our X-ray diffraction data suggest the presence of weak H-H contacts between adjacent [{GaCl(hpp)H}(2)] molecules in the crystal. With the aid of quantum-chemical calculations, the pathway of its formation starting with the adduct (H2ClGaNMe3)-N-. and the pyrimidine hppH were analyzed. [{GaCl(hpp)H}(2)] slowly decomposes at 25 degrees C, a process which presumably leads under H-2 elimination to [{GaCl(hpp)}(2)]. Although we were not yet able to characterize [{GaCl(hpp)}(2)] experimentally, DFT calculations provide information about its likely structure. According to these calculations, the molecule features a Ga-Ga single bond.