Yuko Kani, Tsutomu TakayamaTsutomuSekine and Hiroshi Kudo
Structures of nitridotechnetium(V) amine oxime complexes, [TcN(pnao)(H2O)][BPh4] 1, [TcN(bnao)(H2O)][BPh4] 2 and [TcN(pentao)(H2O)][BPh4] 3 [Hpnao = HON
CMeCMe2NH(CH2)3NHCMe2CMe
NOH; Hbnao = HON
CMeCMe2NH(CH2)4NHCMe2CMe
NOH; Hpentao = HON
CMeCMe2NH(CH2)5NHCMe2CMe
NOH], differing in carbon chain length of the amine oxime ligands, were characterized by X-ray crystallography. These complexes are six-co-ordinated and distorted octahedral. Four nitrogen atoms of the amine oxime ligands are in the equatorial plane and both the nitrido and H2O ligands in the apical positions. These complexes have an asymmetrical intramolecular hydrogen bond between the two oxime oxygen atoms. Their intramolecular O![[hair space]](https://www.rsc.org/images/entities/char_200a.gif)
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O distances are 2.720 Å in 1, 2.512 Å in 2 and 2.531 Å in 3. The longest O![[hair space]](https://www.rsc.org/images/entities/char_200a.gif)
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O distance in 1 is ascribed to a steric effect of the carbon chain length between the amine nitrogens. Namely, the shorter carbon chain of the pnao ligand causes strain on the co-ordinated pnao moiety, and the O![[hair space]](https://www.rsc.org/images/entities/char_200a.gif)
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O distance in 1 is longer than that in 2 and 3 with longer carbon chains.