ja511295h_si_003.cif (21.62 kB)
Pendant Alkyl and Aryl Groups on Tin Control Complex Geometry and Reactivity with H2/D2 in Pt(SnR3)2(CNBut)2 (R = But, Pri, Ph, Mesityl)
dataset
posted on 2015-01-14, 00:00 authored by Anjaneyulu Koppaka, Lei Zhu, Veeranna Yempally, Derek Isrow, Perry
J. Pellechia, Burjor CaptainThe
complex Pt(SnBut3)2(CNBut)2(H)2, 1, was obtained
from the reaction of Pt(COD)2 and But3SnH, followed by addition of CNBut. The two hydride ligands
in 1 can be eliminated, both in solution and in the solid
state, to yield Pt(SnBut3)2(CNBut)2, 2. Addition of hydrogen to 2 at room temperature in solution and in the solid state regenerates 1. Complex 2 catalyzes H2−D2 exchange in solution to give HD. The proposed mechanism of
exchange involves reductive elimination of But3SnH from 1 to afford vacant sites on the Pt center,
thus facilitating the exchange process. This is supported by isolation
and characterization of Pt(SnMes3)(SnBut3)(CNBut)2, 3, when the addition of H2 to 2 was carried
out in the presence of free ligand Mes3SnH (Mes = 2,4,6-Me3C6H2). Complex Pt(SnMes3)2(CNBut)2, 5, can
be prepared from the reaction of Pt(COD)2 with Mes3SnH and CNBut. The exchange reaction of 2 with Ph3SnH gave Pt(SnPh3)3(CNBut)2(H), 6, wherein both SnBut3 ligands are replaced by SnPh3. Complex 6 decomposes in air to form square planar Pt(SnPh3)2(CNBut)2, 7. The complex Pt(SnPri3)2(CNBut)2, 8, was also prepared. Out of the
four analogous complexes Pt(SnR3)2(CNBut)2 (R = But, Mes, Ph, or Pri), only the But analogue does both H2 activation
and H2−D2 exchange. This is due to steric
effects imparted by the bulky But groups that distort the
geometry of the complex considerably from planarity. The reaction
of Pt(COD)2 with But3SnH and CO gas
afforded trans-Pt(SnBut3)2(CO)2, 9. Compound 9 can be converted to 2 by replacement of the CO ligands
with CNBut via the intermediate Pt(SnBut3)2(CNBut)2(CO), 10.
