In the present report mixed cubic clusters [(HAl)(x)(HGa)(y)(HIn)(z)(YH)(4)] (Y = N, P, As, x + y + z = 4) and [(HM)(4)(NH)(k)(PH)(1) (AsH)(m)] (M = Al, Ga, In, k + I + m = 4) are theoretically investigated for the first time. Structural parameters, vibrational frequencies and thermodynamic properties have been obtained at B3LYP/LANL2DZ(d,p) level of theory. At high temperatures, mixed clusters are predicted to be thermodynamically more stable compared to mixture of homoatomic cubanes. Nitrogen-containing clusters have higher stability toward dissociation and are formed more exothermically compared to P, As analogs. Thus, mixed nitrogen clusters are expected to serve as advanced single-source precursors for CVD of mixed alloys, such as AlxGayIn1-x-y N. Variation of the Al:Ga:In ratio is possible by using higher oligomers [HMYH](n) (n = 6-12). (C) 2002 Elsevier Science Ltd. All rights reserved.