Borole Derivatives. 24. Synthesis of Cationic (Arene)(phenylborole)rhodium Complexes. Structures of the Trinuclear Complex (η5-C4H4BPh)Rh(μ3-I)3-Rh(μ,η56-C4H4BPh)Rh(η5-C4H4BMe)·CH2Cl2 and of the Polymeric catena-(μ,η56-1-Phenylborole)rhodium Tetrafluoroborate

The heterocubane [Rh(μ3-I)(C4H4BPh)]4 (1) reacts with Ag+ salts in acetonitrile to give the labile salt [Rh(NCMe)3(C4H4BPh)]BF4 (2). This salt 2 reacts with hexamethylbenzene (hmb) to give the arene complex [Rh(C4H4BPh)(hmb)]BF4 (3), and with mesitylene [Rh(1,3,5-C6H3Me3)(C4H4BPh)]BF4 (4) is obtained. Complex 2 loses acetonitrile under vacuum to produce the polymeric salt catena-[{Rh(μ,η56-C4H4BPh)}BF4]x (5). Insight into the essential structural features of this polymer provided its radial distribution function obtained from a wide-angle X-ray scattering experiment. When treated with acetonitrile, complex 5 regenerates 2 and with pyridine affords [Rh(py)3((C4H4BPh)]BF4 (6). Crystallization from a solution of [Rh(μ3-I)(C4H4BPh)]4 (1) and the corresponding methylborole complex [Rh(μ3-I)(C4H4BMe)]4 (1/1) in CH2Cl2 produces the trinuclear complex (η5-C4H4BPh)Rh(μ3-I)3Rh(μ,η56-C4H4BPh)Rh(η5-C4H4BMe)·CH2Cl2 (7) with a bridging μ,η56-C4H4BPh ligand; complex 7 was characterized by an X-ray structure determination. The resulting molecular structure was used to create a structure model for the monomeric building block of polymer 5.