Sziinmary Interaction of the appropriate electron-rich WE have examined the possibility of preparing transitionolefin and chloride bridged RX1 dimer has yielded the metal carbene complexes using neutral precursors as sources unreactive hans-Pt.ll carbene complex (I) which is of the organic ligand. (For previous synthesis see ref. 1 believed to isomerise thermally to the cis-isomer; the and 2, and possible trapping experiments, ref. 3 and 4.) structure of the trans-coniplex is established inter alia by a Di-~-chlorodichlorobis(triethylphosphine)diplatinum( 11) is single crystal X-ray analysis.known to react readily with ligands, forming mononuclear
Treatment of [PtMe2(bu2bpy)]
(bu2bpy =
4,4‘-di-tert-butyl-2,2‘-bipyridine) with
B(C6F5)3
in the presence of the ligand L gives, under anhydrous conditions,
[PtMeL(bu2bpy)][MeB(C6F5)3] {L = CO
(1a), C2H4 (2a),
PPh3 (3a)}. Similar reactions performed
in the presence
of H2O afford
[PtMeL(bu2bpy)][HOB(C6F5)3]
{L = CO (1b), C2H4
(2b), PPh3 (3b)}. In
the
absence of L, the treatment of
[PtMe2(bu2bpy)] with
B(C6F5)3 and H2O
gives
[Pt{HOB(C6F5)3}Me(bu2bpy)]
(4), the first published example of a
hydroxytris(pentafluorophenyl)borate complex. All of the complexes are fully
characterized by NMR and IR
spectroscopy and, in the case of complex 4, by an X-ray
analysis which confirms the
attachment of the
[HOB(C6F5)3]-
ligand to the square-planar platinum atom via a
Pt−O
bond of 2.062(2) Å. We propose that, in the presence of
water, B(C6F5)3 forms an
adduct
[H2OB(C6F5)3]
(which acts as a strong acid
H[HOB(C6F5)3]) and this then
protonates a Pt−Me bond of [PtMe2(bu2bpy)] forming
CH4 and
[PtMe(bu2bpy)]+[HOB(C6F5)3]-.
This protonolysis methodology provides an alternative route to the
well-established electrophilic methyl-ligand abstraction by B(C6F5)3 for
the production of late transition-metal cations.
Complementary information on these compounds has been obtained from lH, 13C, and l g F n.m.r., including double and triple resonance experiments. The coupling constant, ,J(PNP), covers the range -23.9 to 731.9 Hz, and its magnitude and sign can be related to the proportion of molecules in which the local symmetry of the P-N-P skeleton is C,, rather than C,. Diphosphinoamine conformers of the latter type have been clearly identified for the first time both in solution (for R = Et or Pr', X = Ph, and R = But or CH,But, X = CI) and also in the solid phase.X-Ray analysis of Ph,PN(Pr') PPh,, based on 1 269 diffractometric intensities refined to R = 0.035, shows that the symmetry of the P-N-P skeleton is close to C, in the solid, with P-N = 1.706(4) and 1.71 l ( 4 ) A, and PNP = 122.8(3)".
140.8
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