| # | Species | Formula |
| 4546 | Yttrium, atom | Y | |
| 4547 | Trimethyl yttrium(III) (Geo) | C3H9Y | |
| 4548 | Bicyclopentadienyl yttrium(II) (Geo) | C10H10Y | |
| 4549 | Tricyclopentadienyl yttrium(III) | C15H15Y | |
| 4550 | Y(Cp)2CN (CIGZEX) (Geo) | C19H22NY | |
| 4551 | Y(Cp)2CN (CIGZEX) | C19H22NY | |
| 4552 | Y(III)N3 (FAMVEV) (Geo) | C27H54N3Y | |
| 4553 | Y(III)N3 (FAMVEV) | C27H54N3Y | |
| 4554 | Y(II)(NH3)6 | H18N6Y | |
| 4555 | Y(II)(NH3)6 (Geo) | H18N6Y | |
| 4556 | Y(III)N8(3+) (ROGRUA) (Geo) | C8H32N8Y | |
| 4557 | Y(III)N8(3+) (ROGRUA) | C8H32N8Y | |
| 4558 | Y(III)N9(3+) (XAWXIC) (Geo) | C45H33N9Y | |
| 4559 | Y(III)N9(3+) (XAWXIC) | C45H33N9Y | |
| 4560 | Yttrium(II) oxide (Geo) | OY | |
| 4561 | Yttrium(II) oxide | OY | |
| 4562 | Yttrium oxide, anion | OY | |
| 4563 | Y(Cp)3O (BACZOU) (Geo) | C19H23OY | |
| 4564 | Y(Cp)3O (BACZOU) | C19H23OY | |
| 4565 | Y(III)(Cp)2O2(+) (PEZDAZ) (Geo) | C16H22O2Y | |
| 4566 | Y(III)(Cp)2O2(+) (PEZDAZ) | C16H22O2Y | |