DOE OSTI2020
Cr12CAs5 crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. there are eight inequivalent Cr sites. In the first Cr site, Cr is bonded in a 4-coordinate geometry to two equivalent C and two equivalent As atoms. Both Cr–C bond lengths are 2.16 Å. Both Cr–As bond lengths are 2.50 Å. In the second Cr site, Cr is bonded to four As atoms to form a mixture of distorted edge and corner-sharing CrAs4 tetrahedra. There are two shorter (2.36 Å) and two longer (2.47 Å) Cr–As bond lengths. In the third Cr site, Cr is bonded in a 2-coordinate geometry to two equivalent C and two As atoms. Both Cr–C bond lengths are 2.17 Å. There are one shorter (2.53 Å) and one longer (2.56 Å) Cr–As bond lengths. In the fourth Cr site, Cr is bonded to four As atoms to form a mixture of distorted edge and corner-sharing CrAs4 tetrahedra. There are a spread of Cr–As bond distances ranging from 2.37–2.42 Å. In the fifth Cr site, Cr is bonded in a 5-coordinate geometry to one C and four equivalent As atoms. The Cr–C bond length is 2.41 Å. All Cr–As bond lengths are 2.55 Å. In the sixth Cr site, Cr is bonded in a 5-coordinate geometry to five As atoms. There are one shorter (2.57 Å) and four longer (2.60 Å) Cr–As bond lengths. In the seventh Cr site, Cr is bonded in a 5-coordinate geometry to five As atoms. There are a spread of Cr–As bond distances ranging from 2.53–2.66 Å. In the eighth Cr site, Cr is bonded in a 1-coordinate geometry to one C and four As atoms. The Cr–C bond length is 2.29 Å. There are two shorter (2.58 Å) and two longer (2.62 Å) Cr–As bond lengths. C is bonded in a 9-coordinate geometry to nine Cr atoms. There are three inequivalent As sites. In the first As site, As is bonded in a 9-coordinate geometry to nine Cr atoms. In the second As site, As is bonded in a 9-coordinate geometry to nine Cr atoms. In the third As site, As is bonded in a 9-coordinate geometry to nine Cr atoms.