Lanthanide/actinide boride nanoclusters and nanomaterials based on boron frameworks consisting of conjoined Bn rings (n=7-9)

Extensive global minimum searches augmented with first-principles theory calculations performed in this work indicate that the experimentally observed perfect inverse sandwich lanthanide boride complexes D-7h La2B7- (1), D-8h La2B8 (3), D-9h La2B9- (7) can be extended to their actinide counterparts C-2v AC(2)B(7)(-) (1'), D-8h Ac2B8 (3'), D-9h AC(2)B(9)(-) (7') with a B-n monocyclic ring (n = 7-9) sandwiched by two Ac dopants. Such M2Bn-/0 inverse sandwiches (1/1', 3/3', 7/7') can be used as building blocks to generate the ground-state C-2 La4B13- (2)/Ac4B13- (2'), D-2 La4B15- (4)/Ac4B15- (4'), C-3v/C-3 La4B18 (5)/Ac4B18 (5'), O-h AC(7)B(24)(+) (6'), O-h Ac7B24, T-d Ac4B24 (8'), C-1 La5B24+ (9)/Ac5B24+ (9'), and T-d AC(4)B(2)(9)(-) (10') which are based on boron frameworks consisting of multiple conjoined B-n rings (n = 7-9). Detailed bonding analyses show that effective (d-p)sigma, (d-p)pi and (d-p)delta coordination bonds are formed between the B-n rings and metal doping centers, conferring three-dimensional aromaticity and extra stability to the systems. In particular, the perfect body-centered cubic O-h AC(7)B(24)(+) (6') and O-h Ac7B24 with six conjoined B-8 rings can be extended in x, y, and z dimensions to form one-dimensional Ac10B32 (11'), two-dimensional Ac3B10 (12'), and three-dimensional AcB6 (13') nanomaterials, presenting a B-8-based bottom-up approach from metal boride nanoclusters to their low-dimensional nanomaterials.

Automated summary

In this study, extensive global minimum searches and first-principles theory calculations were used to explore the extended structures of observed lanthanide and actinide boride complexes. The bonding properties and stability of these complexes were also investigated. These findings are of great significance for the design and synthesis of novel boron-based nanomaterials.