Preparation and some reactions of [Os 5 (CO) 19 ]; the molecular structures of [Os 5 (CO) 19 ] and [Os 5 (CO) 16 {P(OMe) 3 } 3 ]

The reaction of [Os6(CO)18] with carbon monoxide at 160 °C and 90 atm leads to the formation of [Os5(CO)19](1) in high yields. This complex crystallises in the triclinic space group P with a= 8.880(4), b= 10.244(5), c= 16.529(7)Å, α= 99.98(2), β= 93.44(2), γ= 110.37(3)°, and Z= 2. The structure was solved by a combination of direct methods and Fourier-difference techniques and refined by blocked-cascade least squares to R= 0.040 for 2 616 …