Five coordinate nickel(II) isothiocyanato and chloro complexes of triazacycloalkanes

✍ Scribed by M. Nonoyama

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 496 KB
• Volume: 20
• Category: Article
• ISSN: 0020-1693
• DOI: 10.1016/s0020-1693(00)94090-8

✦ Synopsis

The new nickel(U) complexes [Ni(pqr-cy)(NCSj2J [Ni(pqr-cy)Cl]CIOb and N&(pqr-cy),(C10J4.nHz0 (n = 4 or 5) have been prepared, where pqr-cy is a

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triazacycloalkane, NH(CH&NH(CHJ,NH(CH,), (p,q = 2,3; r = 2-6). The isothiocyanato complexes are six-coordinate, NCS-bridged octahedral when t (= p + q+r) is small (t Z9), but they are five-coordinate when t is large (tZ9). The five-coordination is peculiar and its origin is attributable to blocking of a coordination site by the backbone polymethylene groups of the pqr-cy ligands. Only the ligands with t=9 and 10 form the chloro complexes, which are Cl-bridged dimers and are also five-coordinate because of the same steric hindrance. It is worth noting that these five-coordinate nickel(U) complexes are isolated from aqueous solutions. The 2:3 perchlorate complexes are octahedral and available only for the ligands with t=9.