The chelating bis(phosphine)
3,5-bis((diphenylphosphino)methyl)pyridine (dppLH,
9) was synthesized from 3,5-lutidine by radical chlorination, followed by reaction with
LiPPh2. Compound 9 was used to prepare Rh
and Pd
complexes. The three complexes (dppL)RhL (L =
PiPr3 (11), PPh3
(12), and CO (13)) are obtained from
Rh2Cl2(COE)4 (COE = cyclooctene) and
HRh(PPh3)4. Compound 9
reacts with (PhCN)2PdCl2 to form the
Pd(II)
complex (dppL)PdCl (14). All complexes are fully
characterized. The X-ray crystal structure of 11 has
been
determined. It crystallizes in the triclinic space group
P1̄ (No. 2) with a = 12.242(3) Å,
b = 14.384(3) Å, c =
11.653(2) Å, α = 98.61(2)°, β = 96.88(2)°,
γ = 106.38(2)°, V = 2023.3(8)
Å3, Z = 2, R = 0.045, and
R
w =
0.052. The Rh(I) center is in a square-planar coordination
environment with the two phosphines of the dppL
ligand framework being trans to each other. The
pyridine nitrogen is unobstructed and available for binding
to
other metal centers. Compound 14 acts as a
metalloligand toward Pd(II) centers to form the trinuclear
complex
{(dppL)PdCl}2PdCl2
(16). N-coordination of a metal moiety and of a Lewis
acid influences the electronic properties
on the Pd center.
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