The reactions of MCl3 with Li-2[PhB((NBu)-Bu-t)(2)] in 1:1, 1:1.5, and 1:2 molar ratios in diethyl ether produced the monoboraamidinates ClM[PhB((NBu)-Bu-t)(2)] (1a, M = As; 1b, M = Sb; 1c, M = Bi), the novel 2:3 boraamidinate complexes [PhB((NBu)-Bu-t)(2)]M-mu-N(Bu-t)B(Ph)N(Bu-t)M[PhB((NBu)-Bu-t)(2)] (2b, M = Sb; 2c, M = Bi), and the bisboraamidinates LiM[PhB((NBu)-Bu-t)(2)](2) (3a, 3a center dot OEt2, M = As; 3b, M = Sb; 3c center dot OEt2, M = Bi), respectively. The 2:3 complexes 2b and 2c were also observed in the reactions carried out in a 1:2 molar ratio at room temperature. All complexes have been characterized by multinuclear NMR spectroscopy (H-1, Li-7, B-11, and C-13) and by single-crystal X-ray structural determinations. The molecular units of the mono-boraamidinates 1a-c are isostructural, but their crystal packing is distinct as a result of stronger intermolecular close contacts going from 1a to 1c. In the novel 2:3 bam complexes 2b and 2c, each metal center is N,N'-chelated by a bam ligand and these two [M(bam)](+) units are bridged by the third [bam](2-) ligand. The structures of the unsolvated bis-boraaminidate complexes 3a and 3b consist of [Li(bam)](-) and [M(bam)](+) monomeric units linked by Li-N and M-N bonds to give a tricyclic structure. Solvation of the Li+ ion by diethyl ether results in a bicyclic structure composed of four-membered BN2As and six-membered BN3AsLi rings in 3a center dot OEt2. In contrast, the analogous bismuth complex 3c center dot OEt2 exhibits a tetracyclic structure. Variable-temperature NMR studies reveal that the nature of the fluxional behavior of 3a-c in solution is dependent on the group 15 center.