Bisazines in the Coordination Sphere of Early Transition Metals

Beckhaus, Rüdiger

doi:10.1002/9783527625468.ch11

Cited by 2 publications

(1 citation statement)

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“…Some remarkable examples are arynes and aryne complexes, vinylidenes and vinylidene complexes, and cyclobutadiene and its complexes . In the course of our investigations concerning the self-assembled formation of multinuclear highly ordered complexes, employing low-valent early transition-metal complexes and aromatic bis-azines as bridging ligands, different reaction patterns have been found . In these investigations, the formation of well-defined molecular squares or rectangles, dehydrogenative , as well as C−C coupling reactions induced by the primary formation of radical anions have been observed (Scheme ) …”

Section: Introductionmentioning

confidence: 95%

Unexpected Trimerization of Pyrazine in the Coordination Sphere of Low-Valent Titanocene Fragments

Jung

Beckhaus

Klüner

et al. 2009

J. Chem. Theory Comput.

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The titanium mediated trimerization of pyrazine leads to the formation of a tris-chelate complex employing a 4a,4b,8a,8b,12a,12b-hexahydrodiyprazino[2,3-f:2',3'-h]quinoxaline ligand (HATH6, 3). The driving force in the formation of the (Cp*2Ti)3(HATH6) complex 2 is attributed to the formation of six Ti-N bonds. We show that density functional theory (DFT) fails to predict quantitatively correct results. Therefore, post-Hartree-Fock methods, such as second-order Møller-Plesset perturbation theory (MP2), in combination with coupled-cluster (CC) methods must be used. Both MP2 and CCSD(T) levels of theory provide endothermic trimerization energies, showing that the plain pyrazine trimer is not stable with respect to decomposition into its monomers. Complete basis set (CBS) results for the MP2 level of theory were computed using explicitly correlated wave functions. With these, we estimate the CCSD(T) CBS limit of the hypothetical trimerization energy to be +0.78 eV. Thus, the trimerization is facilitated by the formation of six Ti-N bonds with a calculated formation energy of -1.32 eV per bond.

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