Synthesis, Characterization, and Electrochemical Properties of Bisosmabenzenes Bridged by Diisocyanides

Treatment of osmabenzene [Os(CHC(PPh 3 )CHC(PPh 3 )CH)Cl 2 (PPh 3 ) 2 ]OH ( 3 ) with various diisocyanides in the presence of NH 4 PF 6 afforded a series of diisocyanide-bridged bisosmabenzenes [(μ-CN−R−NC){Os(CHC(PPh 3 )CHC(PPh 3 )CH)Cl 2 (PPh 3 )} 2 ][PF 6 ] 2 (R = 4,4′-C 6 H 4 -C 6 H 4 ( 5a ), 4,4′-C 6 H 4 CH 2 C 6 H 4 ( 5b ), 4,4′-C 6 H 4 OC 6 H 4 ( 5c ), 1,4-C 6 H 4 ( 5d )) in good yields through ligand substitution reactions. Similarly, reaction of osmafuran [Os(CHC(PPh 3 )C(OEt)O)Cl 2 (PPh 3 ) 2 ] ( 6 ) with 1,4-phenylenediisocyanide produced the diisocynide-bridged bisosmafuran [μ-(1,4-phenylenediisocyanide){Os(CHC(PPh 3 )C(OEt)O)Cl(PPh 3 ) 2 } 2 ]Cl 2 ( 7 ). Bisosmabenzenes containing a chloro and a phosphonium substituent on each metallacycle [(μ-CN−R−NC){Os(CHC(PPh 3 )CHCClCH)Cl(PPh 3 ) 2 } 2 ]Cl 2 (R = 4,4′-C 6 H 4 -C 6 H 4 ( 9a ), 4,4′-C 6 H 4 CH 2 C 6 H 4 ( 9b ), 4,4′-C 6 H 4 OC 6 H 4 ( 9c ), 1,4-C 6 H 4 ( 9d )) could be obtained in modest yields from the reactions of the osmacycle [Os(CH═C(PPh 3 )CH(OH)-η 2 -C≡CH)Cl 2 (PPh 3 ) 2 ] ( 8 ) with corresponding diisocyanides in the presence of NH 4 PF 6 and NaCl via nucleophilic addition reactions. All of these complexes have been fully characterized by 1 H, 31 P{ 1 H}, and 13 C{ 1 H} NMR spectrometry, IR spectrometry, and elemental analyses. Moreover, the structure of 9d has been established by X-ray crystallography. The electrochemical properties of stable bisosmabenzenes 9a − d have been investigated, which revealed that the two metal centers in 9c and 9d can interact with each other through a diisocyanide bridge.