195Pt, 119Sn and 31P NMR characteristics of the complexes trans-[Pt(SnCl3)(carbon ligand)(PEt3)2] (1a-1e) are reported, (carbon ligand = CH3 (1a), CH2Ph (1b), COPh (1c), C6Cl5 (1d), C6Cl4Y (e); Y = meta- and para-NO2, CF3, Br, H, CH3, OCH3, or Pt(SnCl3)(PEt3)2. The values of 1J(195Pt, 119Sn) vary from 2376 to 11895 Hz with the COPh ligand having the smallest and the C6Cl5 ligand the largest value, making a total range for this coupling constant, when the dimer syn-trans-[PtCl(SnCl3)(PEt3)]2 is included, of ca. 33000 Hz. In the meta- and para-substituted phenyl complexes 1J(195Pt, 119Sn) (a) is greater for electron-withdrawing substituents, (b) varies more for the meta-substituted derivatives (5634 to 7906 Hz) than for the para analogues (6088 to 7644 Hz) and (c) has the lowest values when the Pt(SnCl3)(PEt3)2 group is the meta- or para-substituent. The direction of the change in 1J(195Pt, 119Sn) is opposite to that found for 1J(195Pt, 119P). For the aryl complexes linear correlations are observed between δ(119Sn), 1J(195Pt, 119Sn), 1J(195Pt, 31P), 1J(119Sn, 31P) and the Hammett substituent constant σn. δ(119Sn) and 1J(195Pt, 119Sn) are related linearly to v(Pt-H) in the complexes trans-[PtH(C6H4Y)(PEt3)2]; δ(119Sn) and δ(1H) (hydride) are also linearly related. Based on 1J(195Pt, 119Sn), the acyl ligand is suggested to have a very large NMR trans influence. The differences in the NMR parameters for (1a-e) are rationalized in terms of differing σ- and π-bonding abilities of the carbon ligands. The structure of 1c has been determined by crystallographic methods. The complex has a slightly distorted square planar geometry with trans-PEt3 ligands. Relevant bond lengths (Å) and bond angles (°) are: PtSn, 2.634(1), PtP, 2.324(4) and 2.329(4), PtC, 2.05(1); PPtP, 170.7(6), SnPtC, 173.0(3), SnPtP, 92.1(1), 91.7(1), PPtC, 88.8(4) and 88.3(4). The PtSn bond separation is the longest yet observed for square-planar platinum trichlorostannate complexes, and would be consistent with a large crystallographic trans influence of the benzoyl ligand. The PtSn bond separation is shown to correlate with 1J(195Pt, 119Sn).
|Titolo:||195Pt, 119Sn and 31P NMR studies of alkyl, aryl and acyl trichlorostannate complexes of platinum(II): the crystal structure of trans-[Pt(SnCl3)(COC6H5)(PEt3)2]|
ALBINATI, ALBERTO (Primo)
|Settore Scientifico Disciplinare:||Settore CHIM/03 - Chimica Generale e Inorganica|
|Data di pubblicazione:||1985|
|Digital Object Identifier (DOI):||10.1016/0022-328X(85)80276-X|
|Appare nelle tipologie:||01 - Articolo su periodico|