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The international journal for inorganic, organometallic and bioinorganic chemistry
Paper
Dalton Trans., 2004, 3669 - 3677, DOI: 10.1039/B408801H
Multinuclear platinum(II)–amine complexes containing bis(aminopropyl)dicarba-closo-dodecaborane(12) ligands
Susan L. Woodhouse and Louis M. Rendina
Treatment of the bridging bidentate 1,Z-bis(aminopropyl)-1,Z-dicarba-closo-dodecaborane(12)(1,Z-bis(aminopropyl)-1,Z-carborane) ligands of the type 1,Z-{H2N(CH2)3}2-1,Z-C2B10H10(L1, Z= 7, 5) or (L2, Z= 12, 6) with two equivalents of trans-[PtClI2(NH3)]–, followed by halogen ligand metathesis with AgOTf and HCl(aq) afforded the novel diplatinum(II)–amine species cis-[{PtCl2(NH3)}2Ln](7(n= 1) or 8(n= 2), respectively). Similarly, the reaction of L1 or L2 with the labile trans-[PtCl(dmf)(NH3)2]+ afforded trans-[{PtCl(NH3)2}2Ln](OTf)2(9(n= 1) or 10(n= 2), respectively) in good yield and purity. However, isolation of the analogous 1,2-carborane complexes was not possible owing to decomposition reactions that led to extensive degradation of the carborane cage and reduction of the metal centre. The mixed dinuclear complex [cis-{PtCl2(NH3)}–L1-trans-{PtCl(NH3)2}]OTf ( 19) was prepared by treatment of the Boc-protected amine ligand 1-{(Boc)2N(CH2)3}-7-{H2N(CH2)3}-1,7-C2B10H10(L3, 15) with trans-[PtCl(dmf)(NH3)2]+ to yield trans-[PtCl(NH3)2L3]OTf ( 16), followed by acid deprotection of the pendant amine group, complexation with trans-[PtClI2(NH3)]–, and halogen ligand metathesis using AgOTf and HCl(aq). A novel trinuclear species containing 5 was prepared by the addition of two equivalents of 15 to the labile precursor cis-[Pt(dmf)2(NH3)2]2+ followed by acid deprotection of the pendant amine groups. Further complexation with two equivalents of trans-[PtClI2(NH3)]– followed by halogen ligand metathesis using AgOTf and HCl(aq) afforded the triplatinum(II)–amine species [cis-{Pt(NH3)2(L1)2}-cis-{PtCl2(NH3)}2](OTf)2( 23). Complexes 7–10, 19 and 23 represent the first examples of multinuclear platinum(II)–amine derivatives containing carborane cages. Preliminary in vitro cytotoxicity studies for selected complexes are also reported.
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