Bis(N-xylyl-imino)phenyl “NCN” Iridium Pincer Complexes. Thermodynamics of Ligand Binding and C-C Bond Cleavage ChemRxiv 11/02/2023 10529799 10.26434/chemrxiv-2023-r4jt6 Soumyadipa DasSouvik MandalSantanu MalakarThomas J EmgeAlan S Goldman Iridium dibromide complexes of the phenyldiimine ligand 2,6-bis(1-((2,6-dimethylphenyl)imino)ethyl)phenyl, trans-(XyPhDI)IrBr2L, have been synthesized, and relative Ir-L BDFEs have been experimentally determined for a wide range of corresponding adducts of ligands L. An estimate of the absolute enthalpy of Ir-L binding has been obtained from dynamic NMR measurements. The results of DFT calculations are in very good agreement with the relative and absolute experimental values. Computational studies were extended to the formation of adducts of (XyPhDI)IrH2 and (XyPhDI)Ir(I), as well as other (pincer)Ir(I) fragments, (Phebox)Ir(I) and (PCP)Ir(I), to enable a comparison of electronic and steric effects with these archetypal pincer ligands. Attempts to reduce (XyPhDI)IrBr2(MeCN) to a hydride or an Ir(I) complex yielded a dinuclear CN-bridged complex with a methyl ligand on the cyanide-C-bound Ir center (characterized by scXRD), indicating that C-CN bond cleavage took place at that Ir center. DFT calculations indicate that the C-CN bond cleavage occurs at one Ir center with strong assistance by coordination of the CN nitrogen to the other Ir center.

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org/10.26434/chemrxiv-2023-r4jt6 ORCID: https://orcid.org/0009-0008-4667-930X Content not peer-reviewed by ChemRxiv. License: CC BY-NC-ND 4.0    ‡ -N C CH 3 H 3 C C N 33.1 CH 2 C N 1.504 2.50 2 .2 2 1.183 H 2.073 1.123 2.14 7.7 CH 2 C N H 1.104 2. 27 1.942 1.175 2.17 1.989 2.421 18.1 CH 3 C N 2.06 2.096 1.171 2.16 0.8 [0.0] 13.9 ‡ N N Ir = N N Ir = CH 3 H 3 C + H H CH 2 C N H 1.104 2. 27 1 .9 5 6 1.180 1.969 2.399 ‡ 2.13 2.068 1.172 2.12 1.161 1.447 https://doi.org/10.26434/chemrxiv-2023-r4jt6 ORCID: https://orcid.org/0009-0008-4667-930X Content not peer-reviewed by ChemRxiv. License: CC BY-NC-ND 4.0 . Transition state (c) and product (d) of <unassisted= C

https://doi.org/10.26434/chemrxiv-2023-r4jt6 ORCID: https://orcid.org/0009-0008-4667-930X Content not peer-reviewed by ChemRxiv. License: CC BY-NC-ND 4.0