DOE OSTI2020
Nb5Ir7 crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. there are three inequivalent Nb sites. In the first Nb site, Nb is bonded in a 12-coordinate geometry to nine Ir atoms. There are a spread of Nb–Ir bond distances ranging from 2.72–2.88 Å. In the second Nb site, Nb is bonded in a 12-coordinate geometry to eight Ir atoms. There are a spread of Nb–Ir bond distances ranging from 2.77–2.84 Å. In the third Nb site, Nb is bonded to eight Ir atoms to form distorted NbIr8 cuboctahedra that share corners with four equivalent NbIr8 cuboctahedra, corners with four equivalent IrNb6Ir6 cuboctahedra, edges with two equivalent NbIr8 cuboctahedra, and faces with two equivalent NbIr8 cuboctahedra. There are a spread of Nb–Ir bond distances ranging from 2.78–2.86 Å. There are five inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to eight Nb atoms. In the second Ir site, Ir is bonded to four equivalent Nb and two equivalent Ir atoms to form a mixture of distorted edge and corner-sharing IrNb4Ir2 cuboctahedra. Both Ir–Ir bond lengths are 2.78 Å. In the third Ir site, Ir is bonded to six Nb and six Ir atoms to form distorted IrNb6Ir6 cuboctahedra that share corners with two equivalent NbIr8 cuboctahedra, corners with ten IrNb4Ir2 cuboctahedra, edges with eight IrNb4Ir2 cuboctahedra, and faces with seven IrNb8Ir cuboctahedra. There are two shorter (2.78 Å) and three longer (2.85 Å) Ir–Ir bond lengths. In the fourth Ir site, Ir is bonded to eight Nb and one Ir atom to form distorted IrNb8Ir cuboctahedra that share corners with nine IrNb8Ir cuboctahedra, edges with six IrNb4Ir2 cuboctahedra, and faces with six IrNb8Ir cuboctahedra. In the fifth Ir site, Ir is bonded in a distorted water-like geometry to two equivalent Nb and four equivalent Ir atoms.