Figure 3.
Molecular structure of 4a with 50% thermal ellipsoids. All hydrogen atoms are omitted for clarity. Selected bond distances (Å) and angle (deg) for 4a: Ta–N1, 1.782(9); Ta–N3, 2.232(8); Ta–N4, 2.368(3); N2⋯C6, 3.289; Ta–N1–C1, 173.9(7). The structure of 4b is given in the Supporting Information. Selected bond distances (Å) and angle (deg) for 4b: Nb–N1, 1.774(2); Nb–N3, 2.259(2); Nb–N4, 2.370(2); N2⋯C6, 3.296; Nb–N1–C1, 174.2(2).