Reactivity of [M 2 (μ‐Cl) 2 (cod) 2 ] (M=Ir, Rh) and [Ru(Cl) 2 (cod)(CH 3 CN) 2 ] with Na[H 2 B(bt) 2 ]: Formation of Agostic versus Borate Complexes

Treatment of [M 2 (μ‐Cl) 2 (cod) 2 ] (M=Ir and Rh) with Na[H 2 B(bt) 2 ] (cod=1,5‐cyclooctadiene and bt=2‐mercaptobenzothiazolyl) at low temperature led to the formation of dimetallaheterocycles [(Mcod) 2 (bt) 2 ], 1 and 2 ( 1 : M=Ir and 2 : M=Rh) and a borate complex [Rh(cod){κ 2 ‐S,S′‐H 2 B(bt) 2 }], 3 . Compounds 1 and 2 are structurally characterized metal analogues of 1,5‐cyclooctadiene. Metal–metal bond distances of 3.6195(9) Å in 1 and 3.6749(9) Å in 2 are too long to consider as bonding. In an attempt to generate the Ru analogue of 1 and 2 , that is [(Rucod) 2 (bt) 2 ], we have carried out the reaction of [Ru(Cl) 2 (cod)(CH 3 CN) 2 ] with Na[H 2 B(bt) 2 ]. Interestingly, the reaction yielded agostic complexes [Ru(cod)L{κ 3 ‐H,S,S′‐H 2 B(bt) 2 }], 4 and 5 ( 4 : L=Cl; 5 : L=C 7 H 4 NS 2 ). One of the key differences between 4 and 5 is the presence of different ancillary ligands at the metal center. The natural bond orbital (NBO) analysis of 1 and 2 shows that there is four lone pairs of electrons on each metal center with a significant amount of d character. Furthermore, the electronic structures and the bonding of these complexes have been established on the ground of quantum‐chemical calculations. All of the new compounds were characterized by IR, 1 H, 11 B, 13 C NMR spectroscopy, and X‐ray crystallographic analysis.