Dinuclear platinum(II) complexes with bridging twofold deprotonated 2,2′:6′,2″-terpyridine. New molecules with a 3,5-diplatinated-pyridyl inner core: [Pt2(terpy-2H)(Me)
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- 作者：Sergio Stoccoro ; Antonio Zucca ; Giacomo Luigi Petretto ; Maria Agostina Cinellu ; Giovanni Minghetti and Mario Manassero
- 关键词：Platinum ; Cyclometallated compounds ; Nitrogen ligands ; Crystal structure
- 刊名：Journal of Organometallic Chemistry
- 出版年：2006
- 出版时间：15 September 2006
- 年：2006
- 卷：691
- 期：19
- 页码：4135-4146
- 全文大小：372 K
文摘
A series of dinuclear platinum complexes where the metal ions are linked by a twofold deprotonated 2,2′:6′,2″-terpyridine (terpy) has been synthesized. Reaction of cis-[Pt(Me)2(DMSO)2] with terpy in toluene at 90 °C (molar ratio Pt:terpy 2:1) results in activation of the C(3)- and C(5)–H bonds of the inner pyridinic ring to give the cyclometalated dinuclear derivative [Pt2(terpy-2H)(Me)2(DMSO)2] (1a), (trans Me–Pt–N). From complex 1a, substitution of DMSO with neutral two-electron donors, L, allows isolation of a number of new species [Pt2(terpy-2H)(Me)2(L)2] with the same N,CC,N bridging ligand. The “Pt2(terpy-2H)” fragment is very robust: it is not affected by alkylating reagents such as MeI or acids such as HPF6 or even HCl. Nevertheless the latter acid cleaves the Pt–Me bond affording another series of complexes having a chloride in place of a methyl, [Pt2(terpy-2H)(Cl)2(L)2], (trans-Cl–Pt–C). The structure of complex 7, [Pt2(terpy-2H)(Cl)2(PPh3)2], has been solved by X-ray analysis: the platinum atoms are in a tetrahedrally distorted square planar coordination. The inner framework of the molecule is not flat: the dihedral angle between the best planes of the metal ions is 37.2(1)°. The coordinated chlorides can be abstracted to give cationic solvento derivatives or exchanged with other anions such as iodides. Exchange with [BH4]− allows to obtain the corresponding hydrides, examples of very rare C,N cyclometalated platinum(II) hydrides. Finally a two step approach allows the synthesis of unsymmetric derivatives, [Pt2(terpy-2H)(Cl)2(L)(L′)], with different ligands around each platinum atom. The surprising deprotonation of terpy, typically a neutral ligand, points to the potential of the “Pt(Me)2” fragment in the intramolecular C–H bond activation.