Merging the AuCu3- and BaAl4-based structure motifs: flux-assisted synthesis, crystal, and electronic structure of Ca2Pt7XP4−δ phosphide platinides (X = Al, Ti, and Zn)

• Published in: Dalton transactions : an international journal of inorganic chemistry 2022-12, Vol.51 (48), p.18583-18592
• Main Authors: Anastasiya Yu Makhaneva, Elena Yu Zakharova, Nesterenko, Sergey N, Lyssenko, Konstantin A, Kuznetsov, Alexey N
• Format: Article
• Language: English
• Subjects: Aluminum; Charge distribution; Chemical bonds; Electronic structure; Europium; Europium compounds; Fragments; High temperature; Intermetallic compounds; Ionic interactions; Phosphides; Single crystals; Titanium; Topology
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d2dt03367d

Three quaternary phosphide platinides, Ca2Pt7AlP3.00(4), Ca2Pt7TiP3.24(4), and Ca2Pt7ZnP2.78(2), were synthesized by a high-temperature technique using lead as a flux. According to the single-crystal diffraction data, they are isotypic and crystallize in the tetragonal space group I4/mmm with Z = 2 (Ca2Pt7AlP3.00(4): a = 3.9893(6) Å, c = 26.832(5) Å; Ca2Pt7TiP3.24(4): a = 3.99610(10) Å, c = 26.9074(17) Å; Ca2Pt7ZnP2.78(2): a = 4.0020(2) Å, c = 26.5549(17) Å) and thus represent first europium-free compounds of the Eu2Pt7AlP2.95 structure type. Their structures can be described as an intergrowth of the AuCu3- and CaBe2Ge2-type blocks. DFT calculations predict metallic conductivity and non-magnetic state for all three compounds. Bonding analysis based on the Bader charge distribution and ELF topology reveals a combination of localized covalent and ionic interactions in the CaBe2Ge2-type fragments and complex pattern of pairwise, multi-center, and ionic interactions in the AuCu3-type fragments that closely reproduces bonding in the parent Pt3X (X = Al, Ti, Zn) binary intermetallics.