Journal
CHEMISTRY-A EUROPEAN JOURNAL
Volume 17, Issue 47, Pages 13298-13307Publisher
WILEY-BLACKWELL
DOI: 10.1002/chem.201101638
Keywords
amidinate ligands; carboranes; iridium; polymerization; rhodium
Categories
Funding
- Shanghai Science and Technology Committee [08DZ2270500, 08J1400103]
- Shanghai Leading Academic Discipline Project [B108]
- National Basic Research Program of China [2009CB825300]
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Synthesis, structure, and reactivity of carboranylamidinate-based half-sandwich iridium and rhodium complexes are reported for the first time. Treatment of dimeric metal complexes [{Cp*M(mu-Cl)Cl}(2)] (M=Ir, Rh; Cp*=eta(5)-C(5)Me(5)) with a solution of one equivalent of nBuLi and a carboranylamidine produces 18-electron complexes [Cp*IrCl(Cab(N)-DIC)] (1a; Cab(N)-DIC=[iPrN=C(closo-1,2-C(2)B(10)H(10))(NHiPr)]), [Cp*RhCl(Cab(N)-DIC)] (1b), and [Cp*RhCl(Cab(N)-DCC)] (1c; Cab(N)-DCC=[CyN=C(closo-1,2-C(2)B(10)H(10))(NHCy)]). A series of 16-electron half-sandwich Ir and Rh complexes [Cp*Ir(Cab(N)-DIC)] (2a; Cab(N)-DIC=[iPrN=C(closo-1,2-C(2)B(10)H(10))(NiPr)]), [Cp*Ir(Cab(N)-DCC)] (2b, Cab(N)-DCC=[CyN=C(closo-1,2-C(2)B(10)H(10))(NCy)]), and [Cp*Rh(Cab(N)-DIC)] (2c) is also obtained when an excess of nBuLi is used. The unexpected products [Cp*M(Cab(N,S)-DIC)], [Cp*M(Cab(N,S)-DCC)] (M=Ir 3a, 3b; Rh 3c, 3d), formed through BH activation, are obtained by reaction of [{Cp*MCl(2)}(2)] with carboranylamidinate sulfides [RN=C(closo-1,2-C(2)B(10)H(10))(NHR)]S(-) (R=iPr, Cy), which can be prepared by inserting sulfur into the C-Li bond of lithium carboranylamidinates. Iridium complex 1a shows catalytic activities of up to 2.69x10(6) g(PNB) mo1(Ir)(-1) h(-1) for the polymerization of norbornene in the presence of methylaluminoxane (MAO) as cocatalyst. Catalytic activities and the molecular weight of polynorbornene (PNB) were investigated under various reaction conditions. All complexes were fully characterized by elemental analysis and IR and NMR spectroscopy; the structures of 1a-c, 2a, b; and 3a, b, d were further confirmed by single crystal X-ray diffraction.
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