Platinum(II) 1,5-COD Oxo Complexes

Three new types of platinum(II) oxo complexes[(1,5-COD)Pt(μ3-O)(AuL)]2(BF4)2 [1, L = PPh3, PPh2Et, PPh2-i-Pr, P(o-tol)3, P(p-tol)3, P(p-MeOC6H4)3, P(p-CF3C6H4)3], [(1,5-COD)Pt{μ3-O(AuL)2}2](BF4)2 (2), and [(1,5-COD)4Pt4(μ3-O)2Cl2]X 2 (3, X = BF4; 3a, X = CF3SO3)are obtained from oxo/chloro exchange reactions between
(1,5-COD)PtCl2 and [(LAu)3(μ3-O)]BF4. Crystals of 1 (L = PPh3) from CDCl3 are triclinic, P1̄, with (−100 °C)
a = 9.187(4) Å, b = 12.149(3) Å, c = 17.680(6) Å, α = 99.58(2)°, β = 102.86(2)°, γ = 111.63(2)°, V =
1720(1) Å3, and Z = 1. Crystals of 3a from CH2Cl2/toluene are trigonal, P3121, with a = 11.8878(4) Å, c =
29.3193(15) Å, V = 3588.3(3) Å3, and Z = 3. The structure of the cationic portion of 1 shows a planar (COD)Pt(μ-O)2Pt(COD) unit with slightly out-of-plane LAu+ groups linearly coordinated to the oxo ligands. The structure
of the cationic portion of 3a is similar and shows a slightly folded (COD)Pt(μ-O)2Pt(COD) unit with out-of-plane
[(COD)PtCl]+ groups coordinated to the oxo ligands. Solutions of 3 in untreated CH2Cl2 or CD2Cl2 deposit
crystals of [(1,5-COD)4Pt4(μ3-O)2(μ2-OH)](BF4)3 (4) which are monoclinic, P21/n, with a = 18.624(4) Å, b =
14.760(2) Å, c = 15.584(5) Å, β = 95.538(12)°, V = 4264(2) Å3, and Z = 4. The core structure of the cationic
portion of 4 shows a tetranuclear platinum cation in which the metal atoms occupy the corners of a distorted
tetrahedron and two μ3-oxo ligands and one μ2-hydroxo ligand bridge the four platinum atoms. Reaction of 1 (L
= PPh3) with PPh3 gives OPPh3 and [(Ph3P)3PtAuPPh3]BF4 (5) which is also obtained from (Ph3P)4Pt and Ph3PAuBF4. Crystals of 5 from THF are monoclinic, P21/c, with a = 20.426(6) Å, b = 13.4980(11) Å, c = 24.703(9) Å, β = 97.166(15)°, V = 6758(3) Å3, and Z = 4. The structure of 5 consists of an L3Pt−AuL cation where
the Au atom is linear 2-coordinate and the Pt atom is distorted square-planar 4-coordinate.