Lanthanide/actinide boride nanoclusters and nanomaterials based on boron frameworks consisting of conjoined B n 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 La 2 B 7 - (1), D 8h La 2 B 8 (3), D 9h La 2 B 9 - (7) can be extended to their actinide counterparts C 2v Ac 2 B 7 - (1'), D 8h Ac 2 B 8 (3'), D 9h Ac 2 B 9 - (7') with a B n monocyclic ring ( n = 7-9) sandwiched by two Ac dopants. Such M 2 B n -/0 inverse sandwiches (1/1', 3/3', 7/7') can be used as building blocks to generate the ground-state C 2 La 4 B 13 - (2)/Ac 4 B 13 - (2'), D 2 La 4 B 15 - (4)/Ac 4 B 15 - (4'), C 3v / C 3 La 4 B 18 (5)/Ac 4 B 18 (5'), O h Ac 7 B 24 + (6'), O h Ac 7 B 24 , T d Ac 4 B 24 (8'), C 1 La 5 B 24 + (9)/Ac 5 B 24 + (9'), and T d Ac 4 B 29 - (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)σ, (d-p)π and (d-p)δ 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 Ac 7 B 24 with six conjoined B 8 rings can be extended in x , y , and z dimensions to form one-dimensional Ac 10 B 32 (11'), two-dimensional Ac 3 B 10 (12'), and three-dimensional AcB 6 (13') nanomaterials, presenting a B 8 -based bottom-up approach from metal boride nanoclusters to their low-dimensional nanomaterials.