Single crystals of lithium tetra-amidogallate, Li[Ga(NH2)(4)], were obtained from the reaction of Ga metal and LiNH2 in supercritical ammonia at a pressure of 250 MPa and temperature of 400 degrees C. Two structural modifications were characterized by single crystal X-ray diffraction: a=5.849(1) angstrom, b=12.640(3) angstrom, c=6.858(1) angstrom, beta=92.56(3)degrees, Z=4, space group P2(1)/n; a=6.005(1) angstrom, b=7.394(2) angstrom, c=6.005(1) angstrom, beta=103.51(3)degrees, Z=2, space group P2(1). Disodium tetra-amidogallate amide, Na-2[Ga(NH2)(4)]NH2 (a=11.748(2)angstrom, b=6.681(1) angstrom, c=9.665(2) angstrom, Z=4, space group Pnma), was grown ammonothermally (p=130 MPa, T=580 degrees C) as single crystals in the course of synthesizing wurzite GaN employing NaNH2 as an ammono-basic mineralizer. Like known Na[Ga(NH2)(4)], all three novel compounds contain isolated tetra-amidogallate ions [Ga(NH2)4](-) as constituents and likely candidates for dominant dissolved gallium-containing species in ammonothermal GaN synthesis and crystal growth under ammonobasic conditions, accomplishing the material transport. Raman spectroscopy data for Li[Ga(NH2)(4)] in both modifications as well as Na-2[Ga(NH2)(4)]NH2 are provided and discussed. (C) 2014 Elsevier B.V. All rights reserved.