A cyclic tetranuclear Ni(2)Gd(2) complex bridged by amino acidato ligands, with an S = 9 ground state, derived from ferromagnetic spin-coupling between nickel(ii) and gadolinium(iii) ions.

Synthesis and structure of a cyclic tetranuclear Ni(2)Gd(2) complex bridged by amino acidato ligands, with an S = 9 spin ground state, derived from ferromagnetic spin-coupling between S(Gd) = 7/2 and S(Ni) = 1 are reported.

Preparation of platinum(IV) complexes with dipeptide and diimine. X-ray crystal structure and 195Pt NMR spectra.

We prepared platinum(IV) complexes containing dipeptide and diimine or diamine, the [PtCl(dipeptide-N,N,O)(diimine or diamine)]Cl complex, where -N,N,O means dipeptide coordinated as a tridentate chelate, dipeptide=glycylglycine (NH(2)CH(2)CON(-)CH(2)COO(-), digly, where two protons of dipeptide are detached when the dipeptide coordinates to metal ion as a tridentate chelate), glycyl-L-alanine (NH(2)CH(2)CON(-)CHCH(3)COO(-), gly-L-ala), L-alanylglycine (NH(2)CH CH(3)CON(-)CH(2)COO(-), L-alagly), or L-alanyl-L-alanine (NH(2)CHCH(3)CON(-)CHCH(3)COO(-), dil-ala), and diimine or diamine=bipyridine (bpy), ethylenediamine (en), N-methylethylenediamine (N-Me-en), or N,N'-dimethylethylenediamine (N,N'-diMe-en). In the complexes containing gly-L-ala or dil-ala, two separate peaks of the (195)Pt NMR spectra of the [PtCl(dipeptide-N,N,O)(diimine or diamine)]Cl complexes appeared in, but in the complexes containing digly or L-alagly, one peak which contained two overlapped signals appeared. One of the two complexes containing gly-L-ala and bpy, [PtCl(gly-L-ala-N,N,O)(bpy)]NO(3), crystallized and was analyzed. This complex has the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions of a=9.7906(3)A, b=11.1847(2)A, c=16.6796(2)A, Z=4. The crystal data revealed that this [PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex has the near- (Cl, CH(3)) configuration of two possible isomers. Based on elemental analysis, the other complex must have the near- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) configuration. The (195)Pt NMR chemical shifts of the near- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex and the far- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex are 0 ppm and -19 ppm, respectively (0 ppm for the Na(2)[PtCl(6)] signal). The additive property of the (195)Pt NMR chemical shift is discussed. The (195)Pt NMR chemical shifts of [PtCl(dipeptide-N,N,O)(bpy)]Cl appeared at a higher field when the H attached to the dipeptide carbon atom was replaced with a methyl group. On the other hand, the (195)Pt NMR chemicals shifts of [PtCl(dipeptide-N,N,O)(diamine)] appeared at a lower field when the H attached to the diamine nitrogen atom was replaced with a methyl group, in the order of [PtCl(digly-N,N,O)(en)]Cl, [PtCl(digly-N,N,O)(N-Me-en)]Cl, and [PtCl(digly-N,N,O)(N,N'-diMe-en)]Cl.

An FeIII wheel with a zwitterionic ligand: the structure and magnetic properties of [Fe(OMe)2(proline)]12[ClO4]12.

The structure and magnetic properties of a dodecanuclear iron(III) wheel are reported, featuring a bridging zwitterionic ligand.

Boundary Structures in a Series of Lanthanoid Hexacyanocobaltate(III) n-Hydrates and Their Raman Spectra.

Studies on Ln[Co(CN)(6)].nH(2)O (Ln = lanthanoid ions; n = 5, 4) by means of thermal analysis, Raman spectroscopy, and X-ray crystallography were carried out, in order to establish the boundary structures in the series. From the thermal analyses, it was confirmed that the complexes include Ln'[Co(CN)(6)].5H(2)O (Ln' = La to Nd) or Ln"[Co(CN)(6)].4H(2)O (Ln = Sm to Lu). Raman spectra of the complexes suggested a different classification. The complexes having five H(2)O molecules displayed two single bands associated with nu(C-N) at around 2170 cm(-1). The complexes having four H(2)O molecules showed two distinct sets of bands of nu(C-N): one was a singlet, and the other was split. Nevertheless, the complex with Nd, which has five H(2)O molecules, exhibited single and split bands. This implies that the symmetry around Nd is lower than that of other complexes having five H(2)O molecules. According to the X-ray crystal analysis, the Pr complex is Pr[Co(CN)(6)].5H(2)O, hexagonal, P6(3)/m, with a = 7.473(1) Å, c = 14.212(1) Å, and Z = 2. On the other hand, the Nd complex is Nd[Co(CN)(6)].5H(2)O, orthorhombic, C222(1), with a = 7.458(4) Å, b = 12.918(3) Å, c = 14.172(2) Å, and Z = 4. Although the Nd complex has five H(2)O molecules, the crystals are orthorhombic and belong to the space group C222(1). Therefore, the structure of Nd[Co(CN)(6)].5H(2)O is regarded as the boundary structure: one of the coordinated water molecules is disordered, although the structure is essentially the same as that of Pr[Co(CN)(6)].5H(2)O. As Pr in Pr[Co(CN)(6)].5H(2)O changes into Nd, the symmetry around the metal atom is lowered and thus the bands associated with nu(CN) in Nd[Co(CN)(6)].5H(2)O and Sm[Co(CN)(6)].4H(2)O outnumber those of Pr[Co(CN)(6)].5H(2)O. The 5H(2)O complex with Nd loses one water molecule by thermal dissociation and changes into the more stable 4H(2)O complex, whose crystals are orthorhombic and belong to the space group Cmcm. Pr[Co(CN)(6)].5H(2)O also changes into the 4H(2)O complex, orthorhombic and Cmcm, when it dehydrates.