Lanthanide-containing film forming compositions comprising Lanthanide precursors having the general formulae: wherein Ln is a Lanthanide; A is independently N, Si, B, P or O; each E is independently C, Si, B or P; m and n are independently 0, 1 or 2; m+n>1; each R is independently an H or a C1-C4 hydrocarbyl group; L is a −1 anionic ligand selected from the group consisting of NR′2, OR′, Cp, amidinate, β-diketonate, or keto-iminate, wherein R′ is an H or a C1-C4 hydrocarbon group; and L′ is NR″ or O, wherein R″ is an H or a C1-C4 hydrocarbon group. Also disclosed are methods of synthesizing and using the disclosed precursors to deposit Lanthanide-containing films on one or more substrates via vapor deposition processes.