Tuning Reactivity of Platinum(II) Complexes

7.2.1 Synthesis of Pt(II) Compounds (EnPt up to DecPt)
The general synthetic pathway for the dinuclear Pt(II) complexes (EnPt to DecPt)
involved preparing in situ the precursor cation [{cis-PtCl(NH3)2(DMF)] + , 18,37 using
AgClO4 instead of AgNO3 as shown in Scheme 7.2. The DMF is selectively displaced by
involving slow dropwise addition of diaminoalkane to [{cis-PtCl(NH3)2(DMF)] + (1: 1.98
equiv), while stirring at room temperature (30-40 °C) for 24 h in the absence of light.
After removal of the AgCl precipitate, the filtrate was cooled and filtered again to remove
any undesirable impurities and rotary evaporated under low pressure to a volume of
approximately 2 mL and methanol (50 mL) was added. The resulting off-white
precipitate was filtered off and repeatedly recrystallized in minimum H2O/ethanol to
remove a brown sticky mass. The off-white solid of good purity was dried over KOH in a
desiccator, giving the desired dinuclear Pt(II) complexes: [{cis–PtCl(NH3)2}2–μ–
en](ClO4)2 (EnPt) (en = 1,2-diaminoethane), [{cis–PtCl(NH3)2}2–μ–prop](ClO4)2
(PropPt) (prop =1,3-diaminopropane), [{cis–PtCl(NH3)2}2–μ–but](ClO4)2 (ButPt) (but =
1,4-diaminobutane), [{cis–PtCl(NH3)2}2–μ–hex]Cl2 (HexPt) (hex = 1,6-diaminohexane),
[{cis–PtCl(NH3)2}2–μ–oct]Cl2 (OctPt) (oct = 1,8-diaminooctane), and [{cis–PtCl(NH3)2}2–
μ–dec]Cl2 (DecPt) (dec = 1,10-diaminodecane).
2 cis-[Pt(NH 3 ) 2 Cl 2 ] + 2 AgClO 4
DMF, room temp
where, n = 2, 3, 4, 6, 8, 10
2 AgCl (S)
5
2 cis-[Pt(NH 3 ) 2 Cl(DMF)] + + 2ClO 4 -
i. H2N(CH2 ) nNH2 ii. room temp
[cis-{Pt(NH 3 ) 2 Cl} 2 -mu-H 2 N(CH 2 ) n NH] 2+ + 2ClO 4 -
Scheme 7.2: Synthesis of [cis-{PtCl(NH3)2}2-μ-NH2(CH2)nNH2](ClO4)2 (EnPt to DecPt),
where µ = mu.
Their purity was confirmed by micro-elemental analysis, infrared (IR), 1H and 195Pt
NMR. The IR spectra of all the complexes exhibited common characteristic peaks in the