Reaction of t-BuP(O)(OSiMe3)(OH) with Me3Al leads to the formation of [Me2Al(mu -O)(2)P(OSiMe3)(t-Bu)](2) (1) whereas Me2AlCl reacts with Ph2P(O)(OH) to yield [(Cl)(Me)Al(mu -O)(2)PPh2](2) (2). These compounds represent the first examples of functionalized dimeric four-ring type aluminophosphonate systems. The double four-ring type gallophosphonate, namely, [t-BuPO3GaMe](4), reacts with n-Bu4NHF2 under ambient conditions, resulting in the formation of a monomeric gallophosphonate [n-Bu4N][MeGa(t-BuPO2(OH))(3)] (3) These derivatives have been adequately characterized using various spectroscopic techniques and X-ray diffraction studies.