Enthalpies, ΔH(1) ?94.8 ± 6.0 and ΔH(6) ?57.1 ± 5.1 kJ mol?1, of the following reactions have been measured calorimetrically [Pt(trans-stilbene)(PPh3)2](s) + dpcp(g) → (PPh3)2Pt(dpcb)(s) + trans-stilbene(g) (1) [Pt(trans-stilbene)(PPh3)2](s) + bcbd(g) → (PPh3)2Pt(bcpd)(s) + trans-stilbene (g) (6) where dpcp is diphenylcyclopropenone, (PPh3)2Pt(dpcb) is (1,1-bistriphenylphosphine)platinadiphenylcyclobutenone, (PPh3)2O, bcbd is benzocyclobutene-1,2-dione and (PPh3)2Pt(bcpd) is (1,1-bistriphenylphosphine)platinabenzocyclopentanedione, . It is concluded that the five-membered platinacyclo ring system in (PPh3)2Pt(dpcb) is not heavily strained. 相似文献