Synthesis and structure of di-μ-bromo-bis[(1,5-dimethyl-6-oxo-3-(2-pyridyl)verdazyl)copper(I)] †

The complexes [(mu-bmtz(*-))[Cu(PPh(3))(2)](2)](BF(4)) (1) and [(mu-H(2)bmtz)[Cu(PPh(3))(2)](2)](BF(4))(2) (2) (bmtz = 3,6-bis(2'-pyrimidyl)-1,2,4,5-tetrazine and H(2)bmtz = 1,4-dihydro-3,6-bis(2'-pyrimidyl)-1,2,4,5-tetrazine) were obtained as stable materials that could be crystallized for structure determination. 1.2 CH(2)Cl(2): C(84)H(70)BCl(4)Cu(2)F(4)N(8)P(4); monoclinic, C2/c; a = 26.215(7) A, b = 22.122(6) A, c = 18.114(5) A, beta = 133.51(1) degrees; Z = 4. 2.CH(2)Cl(2): C(83)H(70)B(2)Cl(2)Cu(2)F(8)N(8)P(4); triclinic, P1; a = 10.948(2) A, b = 12.067(2) A, c = 30.287(6) A, alpha = 93.82(3) degrees, beta = 94.46(3) degrees, gamma = 101.60(3) degrees; Z = 2. Bmtz itself was also structurally characterized (C(10)H(6)N(8); monoclinic, P2(1)/c; a = 3.8234(8) A, b = 10.147(2) A, c = 13.195(3) A, beta = 94.92(3) degrees; Z = 2). Whereas the radical complex ion contains a planar tetrazine ring in the center, the 1,4-dihydrotetrazine heterocycle in the corresponding complex of H(2)bmtz is considerably folded. Both systems exhibit slight twists between the tetrazine and the pyrimidine rings. The intra-tetrazine distances are characteristically affected by the electron transfer, as is also evident from a comparison with the new structure of free bmtz; the bonding to copper(I) changes accordingly. Spectroscopy including X- and W-band EPR of the radical species confirms that the electron addition is mainly to the tetrazine ring.

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“…For instance, several metal complexes with the tetrazine-containing verdazyl radical function have been described very recently. [42][43][44] …”

mentioning

confidence: 99%

Dicopper(I) Complexes with Reduced States of 3,6-Bis(2‘-pyrimidyl)-1,2,4,5-tetrazine: Crystal Structures and Spectroscopic Properties of the Free Ligand, a Radical Species, and a Complex of the 1,4-Dihydro Form

et al. 2001

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“…Following up on our work with the bisverdazyl bvd, one of our first products with the pyvd ligand was a bromide bridged dimeric copper complex [13] ( Figure 6). This complex, while magnetically rather uninteresting, provides important evidence supporting our earlier assumption that magnetic exchange across the halogen bridge was weak.…”

Section: Copper(i) Complexesmentioning

confidence: 96%

“…In some cases, the metal ion also served as a catalyst for atmospheric oxidation of the tetrazane. [4,13] The Hicks group took an alternative approach, finding that oxidation of the tetrazane with benzoquinone gave a stable co-crystal with hydroquinone. The radical could be separated from this material by chromatography immediately before coordination experiments.…”

Section: Copper(i) Complexesmentioning

confidence: 99%

Coordination Chemistry of Verdazyl Radicals

Brook

2014

Comments on Inorganic Chemistry

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The past 17 years have seen the growth of the coordination chemistry of verdazylsstable free radicals first reported in 1963. Though verdazyls are weakly basic ligands, the ability to synthesize derivatives with chelating substituents, along with the steric similarity of verdazyls to aromatic azine ligands, has resulted in a variety of coordination compounds. Coordination compounds have been reported with Mn 2þ , Co 2þ , Ni 2þ , Cu þ , Cu 2þ , Zn 2þ , Ru 2þ , Ag þ , Cd 2þ , Tb 3þ , Dy 3þ , Gd 3þ and Hg 2þ . These studies have resulted in observations of strong ferromagnetic exchange (up to 400 cm À1 ), ligand-based redox processes, and non-innocent behavior. On the whole, verdazyls are weakly basic ligands in which the half-filled pi orbital can act as either an electron acceptor or an electron donor. The richness of the metal-verdazyl interaction, along with the structural diversity of verdazyls, provides many further opportunities for novel chemistry, as well as fertile ground for the introduction of undergraduates to research.

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“…In the former case, the formation of adducts may increase the stability of the radical [42]. Finally the solvent itself or dissolved dioxygen can be used for in situ oxidation [41,[44][45][46]. This strategy can be useful to favour crystallisation upon precipitation.…”

Section: Synthesis Of the Organic Radicalsmentioning

confidence: 99%

“…[44]). compared to the benzene analogues was their lowered geometric demands, making the bridging cores nearly planar.…”

Section: Figmentioning

confidence: 99%

Organic radicals, a promising route towards original molecule-based magnetic materials

Train

Norel

Baumgarten

2009

Coordination Chemistry Reviews

144

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Synthesis and structure of di-μ-bromo-bis[(1,5-dimethyl-6-oxo-3-(2-pyridyl)verdazyl)copper(I)] †

Cited by 34 publications

References 16 publications

Dicopper(I) Complexes with Reduced States of 3,6-Bis(2‘-pyrimidyl)-1,2,4,5-tetrazine: Crystal Structures and Spectroscopic Properties of the Free Ligand, a Radical Species, and a Complex of the 1,4-Dihydro Form

Dicopper(I) Complexes with Reduced States of 3,6-Bis(2‘-pyrimidyl)-1,2,4,5-tetrazine: Crystal Structures and Spectroscopic Properties of the Free Ligand, a Radical Species, and a Complex of the 1,4-Dihydro Form

Coordination Chemistry of Verdazyl Radicals

Organic radicals, a promising route towards original molecule-based magnetic materials

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