Binary 4f-3d and ternary 4f-3d-X intermetallic compounds, involving 4f (rare-earth, RE) and paramagnetic 3d (transition metal, T) elements, form a class of technologically important materials with various applications like high performant permanent magnets, magnetostrictive based sensing devices, magneto-optical recording, and magnetocaloric devices. The ternary 4f-3d-E phases (with E = main group element) belong to the larger family of polar intermetallic compounds (PICs) which are characterized by significant charge transfer from the electropositive RE to the {TyEx} substructure. Owing to strong relativistic effects in the noble metals, which is strongest for the heaviest 6 th period noble metals like Au and Pt, they can often substitute p-block semimetal elements like triel (Al, Ga, In) and tetrel (Si, Ge, Sn) in polar intermetallic structures without significant structural alteration to form the d-metal rich 4f-3d-(4d)5d systems. This is often referred to as pseudo main-group behaviour, and it allows to stabilise PICs in which the noble metals are negatively polarised. Ternary equiatomic systems with rareearth and noble metal of the platinum group (M = Ru, Rh, Pd, Os, Ir, and Pt) provide interesting platforms to study the peculiarities of the noble metal's intermetallic crystal chemistry because of the abundance of representative phases with relatively simple crystal structures. Overall, the large majority of the reported REMX ternary equiatomic phases are found to crystallize in the prominent orthorhombic TiNiSi (or PbCl2) type or the hexagonal ZrNiAl (ordered Fe2P) type structures, depending on the rare-earth size and valence state, as well as total valence electron count. Nevertheless, the prediction of the structure preference within the classes of ternary equiatomic phases remains very challenging, particularly for the phases with the noble metals involved. Thus, a significant number of these ternary equiatomic phases with noble metal of the platinum group and earliest rare-earth are found to adopt rather the alternative LaNiAl type structure (orthorhombic Pnma-c 6 ) and, so far, the vast majority of the phases adopting this structure type are based on platinum group metals, as exemplified by the electron correlated system CeRuAl with unusually short Ce-Ru distance. The Rh-based ternary equiatomic phases with aluminium, LaRhAl and CeRhAl adopt the LaNiAl type, while other LnRhAl (Ln = Pr, Nd, and Gd) phases crystallize in the TiNiSi type (orthorhombic Pnma-c 3 ). When the trivalent Al is replaced by divalent Zn, all four reported LnRhZn (Ln = La-Nd) phases are found in the LaNiAl type. With another divalent but larger Mg atom, only LaRhMg is found in the La-NiAl type, and CeRhMg is reported in the ZrNiAl type; however, significant Mg/Rh mixing is observed in the letter, yielding the refined composition CeRh1.26(1)Mg0.74(1). The other LnRhMg phases (Ln = Pr-Nd, Sm, Gd-Tm) crystallize in the the TiNiSi type. Furthermore, for the Ir-based phases, LaIrMg and CeIrMg adopt the LaNiAl type, whereas the other LnIrMg (Ln = Pr-Nd, Sm, Gd-Tm) phases crystallize in the TiNiSi type. Only two Pd phases, LaPdAl and ZrPdGa, are known with the LaNiAl type and, previous to our work, there were no reported Os and Pt phases with the LaNiAl type, to the best of our knowledge.