SYNTHESIS AND STRUCTURES OF (MONOORGANYL)AMIDES AND (MONOORGANYL)IMIDES OF ZIRCONIUM AND HAFNIUM

The tetrahalides MCl4 (M = Zr 1a, Hf 1b) react with LiNHtBu with elimination of LiCl to yield [(tBuNH)2MNtBu]2 (3) (M = Zr 3a, Hf 3b). Compounds 3 are thermally instable and oligomerise above 100-degrees-C with elimination of H2NtBu. The reactions of (eta(5)-C5Me5)MCl3 (M = Zr 1c, Hf 1d) with LiNHR (R = tBu 2a, 2,4,6-Me3C6H2 2b, 2,6-iPr2C6H3 2c) lead to (eta(5)-C5Me5)M(NHR)3 (4) (R = tBu, M = Zr 4a, Hf 4b; R = 2,4,6-Me3C6H2, M = Zr 4c, Hf 4d; R = 2,6-iPr2C6H3, M = Zr 4e, Hf 4f). Compounds 4 are thermally very stable and melt without decomposition. When 1c and 1d react with LiNHPh (2d), dimers of composition [(eta(5)-C5Me5)M(NHPh)NPh]2 (M = Zr 5a, Hf 5b) are obtained. The complexes (eta(5)-C5Me5)2MCl2 (M = Zr 1e, Hf 1f) react with 2b to form (eta(5)-C5Me5)2M(NHR)2 (6) (M = Zr 6a, Hf 6b). Pyridine reacts with 4e at 85-degrees-C and replaces one molecule of 2,6-iPr2C6H3NH2 to give (eta(5)-C5Me5)Zr(NHR)NR. Py (7). The single crystal X-ray structures of 4a, 4f, 5b and 7 are described.