10.1021/ic990870l.s001 Douglas B. Grotjahn Douglas B. Grotjahn H. Christine Lo H. Christine Lo Jason Dinoso Jason Dinoso Charles D. Adkins Charles D. Adkins Chunbang Li Chunbang Li Steven P. Nolan Steven P. Nolan John L. Hubbard John L. Hubbard Studies of the Synthesis and Thermochemistry of Coordinatively Unsaturated Chelate Complexes (η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)IrL<sub>2</sub> (L<sub>2</sub> = TsNCH<sub>2</sub>CH<sub>2</sub>NTs, TsNCH<sub>2</sub>CO<sub>2</sub>, CO<sub>2</sub>CO<sub>2</sub>) American Chemical Society 2000 ligand C 2 O 4 CH 3 CN TsNCH 2 CO 2 TsNCH 2 CH 2 NTs Ir C 5 CO 2 CO 2 2000-05-20 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Studies_of_the_Synthesis_and_Thermochemistry_of_Coordinatively_Unsaturated_Chelate_Complexes_sup_5_sup_-C_sub_5_sub_Me_sub_5_sub_IrL_sub_2_sub_L_sub_2_sub_TsNCH_sub_2_sub_CH_sub_2_sub_NTs_TsNCH_sub_2_sub_CO_sub_2_sub_CO_sub_2_sub_CO_sub_2_sub_/3626136 A comparative synthetic, structural, and thermochemical study on a series of chelate complexes containing the fragment (η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Ir [(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Ir(TsNCH<sub>2</sub>CH<sub>2</sub>NTs) (<b>1</b>), (η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Ir(TsNCH<sub>2</sub>CO<sub>2</sub>) (<b>2</b>), (η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Ir(CO<sub>2</sub>CO<sub>2</sub>) (<b>3</b>)] was performed to clarify the roles of carboxylato and sulfonamido ligands. Whereas <b>1</b> and <b>2</b> are monomeric in solution and in the solid state, <b>3</b> appears to exist as an oligomer or polymer, (<b>3</b>)<i><sub>n</sub></i>, which can be broken up by addition of a ligand L such as a phosphine, CO, or 2-methoxypyridine to form (η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Ir(L)(CO<sub>2</sub>CO<sub>2</sub>) (<b>6</b>). The synthesis of (<b>3</b>)<i><sub>n</sub></i> from [(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)IrCl(μ-Cl)]<sub>2</sub> required the use of silver oxalate in CH<sub>3</sub>CN, but if other solvents were used, the bridging oxalato complex (η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)IrCl(μ-η<sup>2</sup>-η<sup>2</sup>-C<sub>2</sub>O<sub>4</sub>)ClIr(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>) (<b>7</b>) was obtained and identified by X-ray diffraction. Enthalpies for reaction of THF-soluble monomers <b>1</b> and <b>2</b> with PMe<sub>3</sub> were determined to be −28.7(0.5) and −28.5(0.4) kcal mol<sup>-1</sup>, respectively. The oligomerization behavior of <b>3</b> may be a result of reduced σ- or π-donation of carboxylato ligands compared to <i>N</i>-tosylamido ligands, because the values for ν<sub>CO</sub> in oxalato and bissulfonamido complexes <b>6</b>−CO and (η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Ir(CO)(TsNCH<sub>2</sub>CH<sub>2</sub>NTs) (<b>4</b>−CO) were 2064 and 2042 cm<sup>-1</sup>, respectively.