A platinum-cyclobutene complex: preparation and structure of bis(triphenylphosphine)-(1,2-dicyanocyclobutene)platinum(0)

The reaction of Pt(C₂H₄)(PPh₃)₂ with 1,2-dicyanocyclobutene affords the new complex bis(triphenylphosphine)(1,2-dicyanocyclobutene)platinum(0), Pt((NC) CC(CN)CH₂CH₂)(PPh₃)₂. The complex has been characterized spectroscopically and by means of a low-temperature X-ray diffraction study. The ³¹P NMR spectrum displays a singlet at 24.34 ppm downfield from external 85% H₃PO₄ with ¹⁹⁵Pt satellites (¹J(¹⁹⁵Pt³¹P) 3561 Hz), consistent with the equivalence of the two PPh₃ groups in the complex. The material crystallizes in space group {A figure is presented} P2₁/n of the monoclinic system with four formula units in a cell at -150°C of a 14.525(3), b 11.981(3),c 19.721(6) Å, β 98.22(1)°. Based on a total of 14108 observations and 173 variables the structure has been refined to values of R and R_w on F_o² of 0.044 and 0.073, respectively. The cyclobutene is attached to the P₂Pt moiety through interaction with the double bond. The resultant P₂PtC₂ portion of the molecule is essentially planar. The PtP distances are 2.284(1) and 2.301(1) Å and the PtC distances are 2.091(3) and 2.077(3) Å. The 1,2-dicyanocyclobutene portion of the complex is essentially planar, with the angle between this plane and that of the P₂PtC₂ plane being 62.6°. The single bonds within the ring have lengths of 1.542(4), 1.546(5), and 1.541(5) Å, while the former double bond has on coordination lengthened to a value of 1.504(4) Å.