COMPLEXATION OF 2,4,6-TRI-TERT-BUTYLPYRIDINE-1,3,5-TRIAZINE LIGAND (L) WITH THE CERIUM(IV) NITRATE ANION - ENCAPSULATION OF PROTONATED [LH(N)](N- FORMATION AND CRYSTAL-STRUCTURES OF CE(NO3)(4)L, (5)(OH2)](-)[CE(NO3)(5)(ETO)](2-)2[NO3](-)[OH](-), 2[LH(2)](2+)[PF6](-)1.5[BF4](-)0.5[PO4](3-) AND [LH(4)](4+)[3NO(3)](-)[PF6](-)() WITH THE HEXAFLUOROPHOSPHATE, NITRATE AND HYDROXIDE ANIONS )

The versatile nature of the ligand 2,4,6-tri-tert-butylpyridyl-1,3,5-t riazine (L) has been established through the preparation and structure determination of four complexes, one containing the cerium(IV) cation and three in which the protonated ligand forms salts with a variety o f anions. Complex 1, Ce(NO3)(4)L, crystallizes in the monoclinic space group P2(1)/c with Z = 4. The cerium atom is 11-coordinate, bonded to L in a tridentate fashion and to four bidentate nitrate anions. The t hree Ce-N bond lengths are 2.720(8), 2.673(7) and 2.734(7) Angstrom. T he Ce-O distances range between 2.522(7) and 2.699(9) Angstrom. In com plexes 2, 3 and 4, protonated cations of the type [LH(n)](n+) are show n to encapsulate simple anions such as PF6-, NO3- and OH- via strong h ydrogen-bond formation. Complex 2, 2[LH(3)](3+) [Ce(NO3)(5)(OH2)](-) [ Ce(NO3)(5)(OEt)](2-), 2NO(3)(-), OH-, is monoclinic, space group P2(1) /n with Z = 4. The structure contains two independent [LH(3)](3+) cati ons, each of which participates in three strong hydrogen bonds. All th ree pyridine ring nitrogen atoms are protonated and both cations form two strong hydrogen bonds to an oxygen atom, from a nitrate and a hydr oxide anion, respectively. In addition, a second nitrate anion forms t wo hydrogen bonds in which two of its oxygen atoms link both cations. In both metal complex anions, the cerium atom is 11-coordinate with Ce -O bond lengths ranging between 2.528(6) and 2.633(6) Angstrom in [Ce( NO3)(5)(OH2)](-) and 2.494(11) and 2.86(2) Angstrom in [Ce(NO3)(5)(OEt )](2-). Complex 3, 2[LH(2)](2+) PF(6)(-)1.5BF(4)(-)0.5PO(4)(3-), belon gs to the triclinic space group <P(1)over bar> with Z = 2. The structu re contains two independent [LH(2)](2+) cations that are linked togeth er via a [PF6](-) anion which forms four strong hydrogen bonds, with t wo fluorine atoms each forming hydrogen bonds to two protonated pyridi ne ring nitrogen atoms in each cation. Complex 4, [LH(4)](4+)3 NO3-PF6 -, is monoclinic, space group P2(1)/c with Z = 4. The [LH(4)](4+) cati on forms two strong hydrogen bonds from two protonated pyridine ring n itrogen atoms to one oxygen atom of a nitrate anion and two weaker hyd rogen bonds from the third protonated pyridine ring nitrogen atom and a protonated nitrogen atom in the central triazine ring. In all struct ures the ligand L remains approximately planar. Copyright (C) 1996 Els evier Science Ltd.