Synthesis of dicationic μ-diborolyl triple-decker complexes [CpCo(μ-1,3-C3B2Me5)M(C6H6)]2+ (M = Rh, Ir)

Abstract

Dicationic triple decker complexes [CpCo(μ 1,3 C 3 B 2 Me 5 )M(C 6 H 6 )] 2+ (M = Rh (3), Ir (4)) were synthesized by the reaction of [CpCo(μ C 3 B 2 Me 5 )MBr 2 ] 2 (M = Rh, Ir) with benzene in the presence of AgBF 4 . The structure of 3(BF 4 ) 2 was determined by X ray diffraction analysis.We have earlier synthesized 1 the bromide complexes [CpCo(μ C 3 B 2 Me 5 )MBr 2 ] 2 (M = Rh (1), Ir (2)), which can be used as synthones for triple decker fragments CpCo(C 3 B 2 Me 5 )M. In particular, it was shown that their reactions with TlCp afford the cationic triple decker com plexes [CpCo(μ C 3 B 2 Me 5 )MCp] + , 1 whereas those with Tl[TlC 2 B 9 H 11 ] give the metallacarborane derivatives CpCo(μ 1,3 C 3 B 2 Me 5 )M(η 7,8 C 2 B 9 H 11 ). 2 In the present study, we report the use of compounds 1 and 2 for the synthesis of dicationic triple decker complexes. Results and DiscussionWe found that the reactions of compounds 1 and 2 with AgBF 4 in nitromethane followed by the addition of benzene yields the 30 electron triple decker complexes [CpCo(1,3 C 3 B 2 Me 5 )M(C 6 H 6 )] 2+ (3, 4) in 80-85% yields (Scheme 1).* It is assumed that the reaction pro ceeds through the intermediate formation of labile solvate complexes [CpCo(μ 1,3 C 3 B 2 Me 5 )M(MeNO 2 ) 3 ] 2+ . We have recently isolated and characterized by X ray diffrac tion analysis considerably more stable analog with aceto nitrile ligands. A similar reaction of [Cp*M(Me 2 CO) 3 ] 2+ with arenes is used for the synthesis of the arene com plexes [Cp*M(arene)] 2+ . 3 The presence of the terminal benzene ligand in dications 3 and 4 makes it possible to consider them as arene triple decker complexes. We recently 4 described the synthesis of similar monocations [CpCo(1,3 C 3 B 2 Me 5 )Ru(C 6 H 6 )] + . * The obtained cationic complexes were isolated as salts with the anion BF 4 -. Scheme 1M = Rh (1, 3), Ir (2, 4) Borofluorides of cations 3 and 4 are dark red solid substances stable in air. They are highly soluble in polar organic solvents, such as acetone and nitromethane. Their structures were confirmed by the data of 1 H and 11 B NMR spectra and high resolution mass spectra. The structure of 3(BF 4 ) 2 was solved by X ray diffraction analysis (Fig. 1).

Dicationic μ‐Diborolyl Arene Triple‐Decker Complexes [CpCo(μ‐1,3‐C3B2Me5)M(arene)]2+ (M = Rh, Ir; Cp = Cyclopentadienyl): Synthesis, Structures, Electrochemistry and Bonding

“…With the aid of computational studies it has been shown that the described complexes and related systems are of interest for molecular electronics16 and for hydrogen storage 17. Herein we describe the synthesis of the first dicationic μ‐diborolyl triple‐decker complexes using bromides [CpCo(μ‐1,3‐C 3 B 2 Me 5 )MBr 2 ] 2 (M = Rh, Ir) as starting materials 18. This methodology is entirely new and is based on the use of specially prepared synthons of triple‐decker complexes, which can be further converted into a wide range of new objects.…”