Crystal and electronic structure of the novel layered rare earth metal boride carbide Gd[sub 2]B[sub 3]C[sub 2]

Journal Article · Wed Mar 30 04:00:00 EST 1994 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00085a015· OSTI ID:7197783

Wiitkar, F; Halet, J F; Saillard, J Y ^[1]; Rogl, P ^[2]; Bauer, J ^[3]

---

1. Universite de Rennes I (France)
2. Universitaet Wien (Austria)
3. Institut National des Science Appliquees, Rennes (France)

The crystal structure of Gd[sub 2]B[sub 3]C[sub 2] has been determined from single-crystal X-ray counter data. Gd[sub 2]B[sub 3]C[sub 2] crystallizes in a unique structure type with the orthorhombic space group Cmmm-D[sub 2h[sup 19]], No. 65, Z = 2. Boron atoms in triangular metal coordination are at a distance d(B1-C) = 0.1597 nm from the B-B chain under bond angles of [var phi][sub B1-B1-B1] = 127.6[degrees]. Branched carbon atoms in 4-fold rectangular metal coordination are at a distance d(B1-C) = 0.1597 nm from the B-B chain under bond angles [var phi][sub C-B2-C] = 180[degrees]. With respect to the structural chemical building blocks and near neighbors, the crystal structure of Gd[sub 2]B[sub 2][sup [6Gd+C,2]]B[sup [2C,[minus]]]C[sub 2][sup [4Gd+2B,[minus]]] is related to the structure type of YB[sup [6Y+C,2]]C[sup [4Y+B,[minus]]], which lacks the nonmetal atom linking the carbon-branched boron zigzag chains. The electronic structure and bonding properties of Gd[sub 2]B[sub 3]C[sub 2] are the metallic and the boron-carbon sublattices is a good starting point to explain the arrangement observed in the nonmetal framework. Thus, a formal charge of 5- per B[sub 3]C[sub 2] unit accounts for the boron-carbon structural arrangement of the B-C net in Gd[sub 2]B[sub 3]C[sub 2]. The electronic structure of the anionic two-dimensional boron-carbon layers is found to be strongly related to that of the boron-carbon layers encountered in ThB[sub 2]C and [alpha]-UB[sub 2]C structures. The possibility of B-B bond alternation is discussed. In the three-dimensional material, the metal-nonmetal bonding occurs primarily through electron donation from the anionic sublattice toward the metallic elements, leading to a metallic behavior.

• OSTI ID: 7197783
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 33:7; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ANIONS
BORIDES
BORON COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CHARGED PARTICLES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRONIC STRUCTURE
GADOLINIUM BORIDES
GADOLINIUM CARBIDES
GADOLINIUM COMPOUNDS
IONS
ORTHORHOMBIC LATTICES
RARE EARTH COMPOUNDS