Variable modes of nickel(II) coordination with macrocyclic ligands based on 1,5-bis(2-mercaptoethyl)-1,5-diazacyclooctane (BME-DACO)

The synthesis, structural characterization, and spectroscopic and magnetic properties of the Ni(II) complexes containing macrocyclic ligands derived from 1,5-bis(2-mercaptoethyl)-1,5-diazacyclooctane are described. The cis orientation of thiolate sulfurs rigidly held in (BME-DACO)Ni(II) (1) permits...

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Bibliographic Details
Published in:Inorganic chemistry 1992-11, Vol.31 (24), p.4965-4971
Main Authors: Darensbourg, Marcetta Y, Font, Ivan, Mills, Daniel K, Pala, Magdalena, Reibenspies, Joseph H
Format: Article
Language:English
Subjects:
CHEMICAL PREPARATION
Chemistry
Chemistry, Inorganic & Nuclear
COHERENT SCATTERING
COMPLEXES
Condensed matter: structure, mechanical and thermal properties
Coordination compounds
CRYSTAL STRUCTURE
DATA
DIFFRACTION
Exact sciences and technology
EXPERIMENTAL DATA
INFORMATION
Inorganic chemistry and origins of life
Inorganic compounds
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
LATTICE PARAMETERS
LIGANDS
Metal complexes
MOLECULAR STRUCTURE
NICKEL COMPLEXES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
Physical Sciences
Physics
Preparations and properties
SCATTERING
Science & Technology
Structure of solids and liquids
crystallography
Structure of specific crystalline solids
SYNTHESIS
TRANSITION ELEMENT COMPLEXES 400201 > Chemical & Physicochemical Properties
VOLTAMETRY
X-RAY DIFFRACTION
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Description
Summary:The synthesis, structural characterization, and spectroscopic and magnetic properties of the Ni(II) complexes containing macrocyclic ligands derived from 1,5-bis(2-mercaptoethyl)-1,5-diazacyclooctane are described. The cis orientation of thiolate sulfurs rigidly held in (BME-DACO)Ni(II) (1) permits high-yield template syntheses of macrocycle ligands. Thus reaction of l with 1,3-dibromopropane gives a four-coordinate N2S2Ni complex, (4,8-dithia-1,11-diazabicyclo-[9.3.3]heptadecane)nickel(II) bromide, [Ni(bicycle)]Br2 (3a). Alkylation of 1 with bis(2-iodoethyl) ether results in a six-coordinate complex, containing a pentadentate. N2S2O donor macrocyclic ligand, (7-oxa-4, 10-dithia- 1, 1 3-diazabicyclo[11.3.3]nonadecane)iodonickel(II)iodide, [(Ni(ether)I]I(4a). Complex 3a crystallizes in the monoclinic P2(1)/c (No. 14) space group with a = 17.384 (7) angstrom, b = 15.529 (6) angstrom, c = 15.153 (4) angstrom, beta = 104.42 (3)-degrees, V = 3962 angstrom3, and Z = 8. Complex 4b [Ni(ether)I]BPh4, Crystallizes in the orthorhombic P2(1)2(1)2(1) (No. 18) space group with a = 10.016 (2) angstrom, b = 11.834 (3) angstrom, c = 30.127 (8) angstrom, V = 3570 (1) angstrom3, and Z = 4. In pseudo-square-planar 3a (a 2.947 (2) angstrom bromide interaction with Ni(II) creates a virtual square pyramid), the metalladiazacyclohexane rings are in the chair/boat configurations. However,in pseudooctahedral 4b, the folding back of the eight-membered NiS2C4O ring to accommodate Ni-O bonding and the presence of an iodide ligand trans to the oxygen enforce the uncommon chair/chair configuration of the fused metalla rings. The larger macrocycle of 4 creates a larger N2S2 cavity, with Ni-S distances in 4b of 2.405 (2) and 2.362 (2) angstrom and in 3a of 2.188 (3) and 2.201 (3) angstrom. The relative accessibility of the Ni(I) oxidation state determined by cyclic voltammetry reflects this cavity size, with the larger yielding more positive values of the Ni(II/I) couple. Electrochemical studies of the ion-exchanged derivatives of 4 found the following dependence of the Ni(II/I) redox couple on the nature of the nickel-bound halide ligand: E1/2(I-) > E1/2(Br-) > E1/2(Cl-). Factors which influence the interconversion between four- and six-coordination of 3 and 4 are explored.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic00050a012