Trans alkenylpyridine and alkenylamine complexes of platinum

Addition of cis-cyclooctene (coe) to K²PtCl₄ gives trans- [PtCl₂(coe)]₂ (1), which reacts with excess coe to give trans- PtCl₂(coe)₂ (2). Compound 2 was characterized by an X-ray diffraction study and crystals were found to be triclinic, a = 5.7838(5), b = 7.4347(6), c = 9.9972(9) A, α = 83.924(1), β = 87.844(2), γ = 73.546(1)°, Z = 1, with space group P1. Addition of 4-vinylpyridine (4vp) to 1 gave trans-PtCl₂(4vp)₂ (5) which was also characterized by an X-ray diffraction study. Crystals of 5 were monoclinic, a = 8.2255(6), b = 12.8254(10), c = 6.9624(5) A, β = 98.8230(10)°, Z = 2, with space group P2₁/c. Although alkenylamines react with 1 to give a mixture of products, addition of one equivalent of apve (H₂NCH₂CH₂CH₂OCH=CH₂) to 1 cleanly afforded the organometallic product trans- PtCl₂(coe)(thmo) (thmo = tetrahydro-2-methyl-1,3-oxazine) arising from a metal-catalyzed intramolecular hydroamination of the starting alkenylamine. Initial investigations into the functionalization of metal complexes containing pendant alkene groups have shown that catecholborane can be added in some cases, using a rhodium catalyst, to give the corresponding organoboronate ester platinum compounds.