Browsing by Author "Doxsee, Daniel D."

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    Preparation and nuclear magnetic resonance characterization of N-bonded complexes of platinum(II) with phosphorus-nitrogen rings containing three-coordinate chalcogens: x-ray structure of [PtCl2(PEt3)]2(Ph4P2N4Se2Et2)
    (1993) Chivers, Tristram; Doxsee, Daniel D.; Hilts, Robert; Parvez, Masood
    The reaction of 1,5-Ph4P2N4S2Ph2 with [PtCl2CPEt3)]2 in chloroform at 60 °C produces the 1:1 adduct trans-PtCl2(PEt3)(Ph4P2N4S2Ph2) in which the platinum is attached to a nitrogen atom on the basis of 31P nmr spectroscopy. By contrast, the corresponding reactions of 1,5-Ph4P2N4Se2R2 (R = Me, Et, Ph) produce the 2:1 adducts [PtCl2(PEt3)]2(Ph4P2N4Se2R2) (7a, R = Me; 7b, R = Et; 7c, R = Ph) which have been characterized by 1H, 31P and 77Se nmr spectroscopy and, in the case of 7b, by X-ray crystallography. Crystals of 7b are monoclinic, space group C2/c, with a = 27.803(7) Å, b = 12.378(7) Å, c = 15.752(8) Å, β = 115.49(2)°, V = 4893(3) Å3, and Z = 4. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at R = 0.037 and Rw = 0.022. The platinum centres in 7b are attached to distal nitrogen atoms of the disordered P2N4Se2 ring. The reaction of the six-membered ring Ph4P2N3SPh with [PtCl2(PEt3)]2 in dichloromethane at 23 °C occurs in a regiospecific manner to give the 1:1 adduct PtCl2(PEt3)(Ph4P2N3SPh) in which, on the basis of 31P nmr spectroscopy, the platinum is coordinated to a nitrogen atom between phosphorus and sulfur.
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    Preparation and phosphorus-31 and selenium-77 NMR spectra of platinum and palladium complexes of a P2N4Se2 ring
    (1993) Chivers, Tristram; Doxsee, Daniel D.; Hilts, Robert; Parvez, Masood
    The reaction of 1,5-Ph4P2N4Se2 with Pt(PPh&(CH2=CH2) or Pd(PPh3)l in toluene at 0 OC produces the 92- Se,Se'-bonded complexes M(PPh3)2( 1,5-Ph4P~N4Sez) (2a, M = Pt; 2b, M = Pd) characterized by their 3IP and "Se NMR spectra. Simulation of the 77Se NMR spectra gave detailed coupling information for 2a and 2b. Heating 2a or 2b in boiling toluene produces the corresponding ~2-Se,N-p,r11-Se'-bonded dimers [M(PPh3)( 1,5-Ph&N4- Sez)12 (3a, M = Pt; 3b, M = Pd). Variable-temperature 31P NMR spectra of 3a reveal a fluxional process which is proposed to involve a [ 1,3]-metallotropic shift. The reaction of 1,5-Ph4P2N4Se2 with [PtC12(PEt3)]2 in CHzCl2 produces the #-N-bonded adducts [PtClZ(PEt3)],(1,5-Ph4PzN4Se2) (4a, n = 1; 5, n = 2). The two PtC12(PEt3) groups in 5 are attached to distal nitrogen atoms of the P2N4Se2 ring, which retains a folded structure with d(Se-Se) = 2.594 A. Treatment of 4a with Pt(PPh3)2(CHyCH2) produces the pZ,s3-Se,Se',N-bonded complex Pt(PPh3)z( 1,s- PhP2Nfie2) [PtC12(PEt3)] identified by "PNMR spectroscopy. Reaction of [Li[Ph&NBe2Ph](THF)]z, generated from the combination of 1,5-Ph4P~N4Sez and phenyllithium in THF, with cis-PtCl~(PEt3)~ yields the +Se-bonded complex trans-PtCl(PEt3)z(PhdP2N&e2Ph)(7a). Variable temperature 31P NMR spectra of 7a reveal a two-site exchange process involving the two PEt3 ligands, which is proposed to occur via rotation about the PtSe bond. Line-fitting analysis yielded the thermodynamic parameters for this process.
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    Preparation, spectroscopic and structural characterization of η1-N and η2-Se,Se′ complexes of a P2N4Se2 ring
    (1992) Chivers, Tristram; Doxsee, Daniel D.; Hilts, Robert; Meetsma, Auke; Parvez, Masood; Grampel, Johan C. van de
    The reaction of 1,5-Ph4P2N4Se2, 1, prepared by the treatment of Ph2PN2(SiMe3)3 with a mixture of SeCl4 and Se2Cl2 in acetonitrile, with [PtCl2(PEt3)]2 gives the adducts [PtCl2(PEt3)]n[η1-N-Ph4P2N4Se2](2, n- 1; 3, n- 2) in which the P2N4Se2 ring is shown by an X-ray structural determination of 3 to contain a transannular Se–Se interaction; the oxidative addition of 1 or 2 to Pt(C2H4)(PPh3)2 produces the corresponding η2-Se,Se′ complexes.