Crystal structures of 5,12-dimethyl-1,4,8,11-tetraazacyclotetradecane cobalt(III) mono-phenylacetylide and bis-phenylacetylide

Abstract

The crystal structures presented herein consist of two positively charged CoIII(DMC) acetyl­ide complexes that take on a pseudo-octa­hedral symmetry and can be synthesized under weak-base conditions.

New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl Complexes Based on Cobalt(III)(cyclam)(C2NAPMes)

“…The Co centers of 1a , 1c and 3b assume pseudo‐octahedral geometries with the alkynyl and Cl/alkynyl trans ‐ to each other. Consistent with previous studies, the Co–C1 bond length is significantly longer in the bis‐NAP Mes species, 3b [1.933(4) Å], compared to the mono‐NAP Mes , 1a [1.859(3) Å], which can be attributed to the trans ‐influence as the increased donor strength provided by the alkynyl compared to the Cl in the axial position results in a weaker bond , , , . The influence of the electron withdrawing/donating character of the alkynyl ligand on the Co–C1 bond length can be observed across the literature with [Co(cyclam)(C 2 CF 3 ) 2 ] + (1.917) < [Co(cyclam)(C 2 C 6 F 5 ) 2 ] + (1.926) < 3b (1.933) < [Co(cyclam)(C 2 C 6 H 4 ‐4‐NMe 2 ) 2 ] + (1.942) < [Co(cyclam)(C 2 Ph) 2 ] + (2.001) .…”

“…Consistent with previous studies, the Co-C1 bond length is significantly longer in the bis-NAP Mes species, 3b [1.933(4) Å], compared to the mono-NAP Mes , 1a [1.859(3) Å], which can be attributed to the trans-influence as the increased donor strength provided by the alkynyl compared to the Cl in the axial position results in a weaker bond. [19,21,22,[31][32][33] The influence of the electron withdrawing/donating character of the alkynyl ligand on the Co-C1 bond length can be observed across the literature with [Co(cyclam)(C 2 CF 3 ) 2 ] + (1.917) [34] < [Co(cyclam)(C 2 C 6 F 5 ) 2 ] + (1.926) [22] < 3b (1.933) < [Co(cyclam)(C 2 C 6 H 4 -4-NMe 2 ) 2 ] + (1.942) [21] < [Co(cyclam)(C 2 Ph) 2 ] + (2.001). [35] The electron withdrawing species (-CF 3 , C 6 F 5 , and -NAP Mes ) have notably shortened bond lengths (Co-C) compared to the electron donating groups [-NMe 2 and -N(Ph-4-OMe) 2 ] due to reduced antibonding contribution from the π(C≡C) to the Co dπ.…”

“…ESI-MS: [M] + , 630.2; 1 H NMR (300 MHz, [D]methanol) δ = 9.08 (d, J = 9.0 Hz, 1H), 8.65 (d, J = 7.4 Hz, 1H), 8.54 (d, J = 7.9 Hz, 1H), 8.04 (d, J = 7.9 Hz, 1H), 8.00-7.90 (m, 1H), 7.06 (s, 2H), 5.38 (s, 4H), 3.10-2.90 (m, 4H), 2.89-2.64 (m, 14H), 2.57 (d, J = 13.3 Hz, 2H), 2.37 (s, 3H), 2.04 (s, 6H). Visible spectrum, λ max (nm, ε (M -1 cm -1 )): 396 (33,400), 480 (534); IR (cm -1 ): ν ˜= O: 1652 (s), 1700 (s); C≡C: 2103 (s). Elem.…”