Transformation of a trialkynylphosphine oxide to a 2-alkylidene-1,2-dihydro-3-phosphete P-oxide ligand by Pt-H addition and rearrangement reactions. Activation of molecular hydrogen by a platinum(II) complex

Abstract

1007anisotropic thermal parameters for all except 23 non-hydrogen atoms, due to the limitations of SHELXTL. The 23 atoms left as isotropic were normal carbon atoms. Hydrogen atoms were included at calculated positions by using a riding model, with C-H of 0.96 A and UH = 1.2U*c. The largest shift in the final cycle of refinement was 0.005 for y of C(57). There are no exceptionally short intermolecular contacts in the structure.The final difference map has 50 peaks with heights between 1.0 and 2.7 e A-3. Four of the largest fifteen appear to be hydride ligands. These were not well-behaved upon refinement, but contour maps drawn through and parallel to the Ir2CuC12(C0)2 (20) The absorption correction is made by using Program XABS, B.Moezzi, Ph.D. Dissertation, University of California, Davis. The program obtains an absorption tensor from F, -F, difference.plane reveal that these electron densities have radial symmetry and central maxima. Their presence can also be inferred from the vacant coordination sites at Ir. Acknowledgment. We thank t h e United States National Science Foundation (CHE-8519557) and NATO (86/0793) for support, Johnson Matthey Inc. for a loan of iridium salts, M. Cowie for useful discussion and permission to quote his results, a n d K. Caulton for comments. Supplementary Material Available:Complete tables of bond distances and angles, hydrogen atom positions, and anisotropic thermal parameters (7 pages); a listing of structure factor amplitudes (70 pages). Ordering information is given on any current masthead page. Addition of the Pt-H bond of [~~~~S-P~(H)(PE~~)~(THF)]+ to the CEC triple bond of the alkynylsubstituent of O=PPhz(CzCPh) occurs regioselectively to give a Pt,P p-alkenylidene complex. Similar addition of a Pt-H bond to the trialkynylphosphine oxide O = P ( C E C C M~~)~ presumably occurs also, but a facile insertion rearrangement takes place to form a novel 2-alkylidene-l,2-dihydro-3-phosphete P-oxide ligand. Complexes containing this heterocyclic alkenyl ligand react with molecular hydrogen a t -78 OC and at atmospheric pressure to give neutral monohydride complexes. The X-ray structure of one such complex has been determined (trans-Pt C=C(CMe3)P(OBF3) ( C 4 C M e 3 ) C = C ( CMe3) (H)] [P( PI-)^] 2( H)]; monoclinic; B1/c; 2 = 4; u = 11.006 (4) d , b = 21.435 (5) A, c = 19.518 (5) A; ( ? = 100.72 (3)'. Other reaction chemistry and a discussion of proposed mechanisms for the formation of these unusual complexes are reported.

Alkyl and hydrido phenoxo complexes of nickel(II), palladium(II), and platinum(II). Hydrido amido complexes of palladium

“…This deviation is also seen in írons-PtH(OPh) (PEt3)2168 but to a lesser extent. The nickel-oxygen distance of 1.949 (7) Á in 2 is shorter than the platinum-oxygen bond length in fr<zro-PtH(OPh)(PEt3)2'6a by approximately 0.1 Á. The Ni-O-C(l) angle of 123.0 (4)°s uggests sp2 hybridization for the phenoxide ligand.…”

“…Mp: 120-122 °C. NMR (C6D6): 6 -23.03 (tr, VpHícw = 72 Hz, 1 H, Ni-tf), 2.98 (s, 12 H, P-Ctf2), 7.07-7.23 (m, 30 H, CH2C6tf5). 31P|'H) NMR (C6D6): S 24.33 (s).…”

“…The solid was filtered out and redissolved in C6H6 (2 mL), and the solution layered with pentane in an attempt to crystallize 5, yielding an impure gray solid, 0.214 g (56%). Mp: 100-101 eC dec. NMR (C6H6): -13.99 (tr, VpH(cil) = 11 Hz, 1 H, Ni-JT), 3.17 (s, 12 H, P-CH2), 7.05 (m, 18 H, CH2C6//5) 7.19 (m, 12 H, CH2C6tf5). 3IP|'H| NMR (C6D6):…”

“…Complex 11 exhibits 'H NMR resonances similar to those for complex 10. For example, the aromatic and hydride resonances are 7.24 (t, J = 8 Hz, m-C6H¡), 6.74 (d, J = 8 Hz, 0-CtHs), 6.45 (t, J = 7 Hz, o-C6/f5), and -13.89 (s, Pd-H). The N-H resonance is obscured by the broad resonances from the cyclohexyl protons between 2.2 and 1.1 ppm.…”

Cobalt- or rhodium-catalyzed synthesis of 1,2-dihydrophosphete oxides via C–H activation and formal phosphoryl migration

“… 9 In 1989, Lukehart developed stoichiometric reactions of trialkynylphosphine oxide and platinum hydride that involve Pt–H addition and rearrangement reactions ( Scheme 1b1 ). 10 In 1997, Majoral reported synthesis of metallacycle-supported 1,2-dihydrophosphete via coupling of bis(alkynyl)phosphines with zirconocene-benzynes ( Scheme 1b2 ). 11 Very recently, Cummins realized phosphinidene transfer to cyclopropenones for synthesis of phosphet-2-ones( Scheme 1b3 ).…”