A series of four tripodal phosphine oxide ligands, (OPR2)(2)CHCH2POR2 (1a-1d), and four mixed phosphine-phosphine oxide ligands, (OPR2)(2)CHCH2PR2 (3a-3d), were synthesized and coordinated to yttrium to produce Y(NO3)(3)[(OPR2)(2)CHCH2POR2] (2a-2d) and Y(NO3)(3)[(OPR2)(2)CHCH2PR2](OPPh3) (4a-4d) complexes. The previously. reported ligand la and unknown phosphine oxide ligands 1b-1d were generated in an unprecedented trisubstitution reaction of bromoacetaldehyde diethyl acetal, while the novel partially reduced ligands 3a-3d were synthesized from 1a-1d according.. to a known literature protocol for the selective monoreduction of bisphosphine oxides. The neutral yttrium complexes 2a-2d are nine coordinate and display a tricapped trigonal-prismatic geometry. Complexes 4a-4d are also neutral, nine-coordinate species and have a pendant phosphine functionality, which provides the potential to form bimetallic early-late transition-metal complexes. Additionally, yttrium complexes 2a-2d were activated with base and tested for the ring-opening polymerization of epsilon-caprolactone, but the results showed that base by itself was significantly more effective than the yttrium species investigated.