Carbonylation of Hydrido–Phosphanido‐Bridged Dinuclear Platinum Complexes

The carbonylation of the solvento species [(PHCy 2 )(L)Pt(μ‐PCy 2 )(μ‐H)Pt(PHCy 2 ){ κ P ‐P(OH)Cy 2 }][BF 4 ] 2 ( Pt–Pt ) ([ 1 ‐L] 2+ , L = CH 2 Cl 2 , thf, CH 3 CN) led to the formation of a singly bridged dicarbonyl Pt I compound syn ‐[(PHCy 2 )(CO)Pt(μ‐PCy 2 )Pt{ κ P ‐P(OH)Cy 2 }(CO)] + ( Pt–Pt ) ( 2 + ). The reaction proceeded in two steps: 1) Substitution of L by CO to give the intermediate syn ‐[(PHCy 2 )(CO)Pt(μ‐PCy 2 )(μ‐H)Pt(PHCy 2 ){ κ P ‐P(OH)Cy 2 }] 2+ ( Pt–Pt ) ([ 1 ‐CO] 2+ ) and 2) uptake of a second molecule of CO and elimination of [PH 2 Cy 2 ] + (as the BF 4 – salt) to give 2 + . The dicarbonyl complex [ 2 ][BF 4 ] was also synthesized starting from the dicyclohexylphosphanido‐bridged complex [(PHCy 2 )Pt(μ‐PCy 2 ){ κ 2 P , O ‐μ‐P(O)Cy 2 }Pt(PHCy 2 )]( Pt–Pt ) ( 5 ). In this case the first step consisted of the carbonylation of 5 to give [(PHCy 2 ) 2 Pt(μ‐PCy 2 )Pt{ κ P ‐P(O)Cy 2 }(CO)]( Pt–Pt ) ( 6 ), which was transformed into 2 + by protonation with HBF 4 under an atmosphere of CO. Prolonged reaction times for the carbonylation of [ 1 ‐L] 2+ in halogenated solvents resulted in the formation of the symmetrical dicarbonyl compound syn ‐[(CO)(PHCy 2 )Pt(μ‐PCy 2 )Pt(PHCy 2 )(CO)] + ( Pt–Pt ) ( 3 + ) along with Cy 2 P(H)OBF 3 . Complexes 6 and [ 1 ‐L][BF 4 ] 2 were also formed by the carbonylation of 5 and [ 1 ‐OMe 2 ][BF 4 ] 2 in the solid state.