Binuclear platinum(I1) complexes of 1,1,4,7,10,10-hexaphenyl- 1,4,7,10-tetraphosphadecane (P4) containing various bridging ligands as spacers between the P4 coordination units

The former reported complex ci.r,;eso-[Pt,Cl,P4] (l), w h ere P4 is 1,1,4,7,10,10-hexaphenyl-1,4,7,lO-tetraphosphadecane and which contains a chloro bridge only in solution, is fully characterized by an X-ray structure analysis: triclinic, Pi; a = 8.395(2), b = 11.675(2), c = 13.717(3) A, (~=92.54(3), p= 98.93(3), y= 109.28(3)", R =0.059 for 2872 observed reflections (F> 6.0(F)). It shows an open-mode dimer with a Pt-Pt distance of 6.916(l) A and a cis P4 configuration. A comparison with the X-ray structure of cis,rac-[Pt,Cl,P4] (2) is given. 2 also contains a chloro bridge only in solution, and these chloro bridges of 1 or 2 are replaced by hydride in rut-[Pt,H&-H)P4](BF4) (3), by pyridine in rue-[Pt&l&-C5H5N)P4](BPh4)Z (4), by pyrazolate (Pz) in rat-[Pt,Cl&-Pz)P4](BPh,)) (5), and by imidazolate (Im) in meso-[Pt,Cl,(p-Im)P4](BPh,) (6) and rut-[Pt,Cl&- Im)P4](BPh,) (7). In rat-[Pt,C&-Cl)(p-dppa)P4](BPh,) (S), w h ere dppa is 1,2-bis(diphenylphosphino)acetylene, an additional dppa bridge occurs. The complexes have been characterized by isSPt{'H}, 3'P{1H} and 'H NMR spectroscopy, elemental analyses and melting points. 3, 4, 5, 7 and 8 show that rut-P4 is flexible enough to allow the reaction with bridging ligands of very different sizes, whereas in the case of meso-P4 only the incorporation of imidazolate (6) is possible. This different behavior of meso- and rut-P4 is discussed with respect to the X-ray structures of 1 and 2, showing that completely different rotation isomers could be responsible for the observed reactivity. In meso-[Pt,Cl(w-Cl)(SnCl,)P4](BPh,) (9) the oxidative addition of SnCl, is only possible at a terminal Pt-Cl bond.