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Issue 10, 1991
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closo-Monocarbaboranes as ligands for transition metals: synthesis and reactivity of exo-diphosphineplatinum-closo-monocarbaborane complexes; structure of [Pt{But2P(CH2)2PBut2}(closo-CB11H12)][CB11H12]

Abstract

Protonation of the complexes [PtR2(L–L)][R = Me, L–L =(C6H11)2P(CH2)3P(C6H11)21a; But2P(CH2)3PBut2, 1b; But2P(CH2)2PBut21c; or But2PCH2C6H4CH2PBut2, 1d; R = CH2But, L–L =(C6H11)2P(CH2)3P(C6H11)2, 2a; But2P(CH2)3PBut2, 2b; or But2P(CH2)2PBut2, 2c] with the monocarbaborane acid HCB11H12 in diethyl ether at 0 °C affords the exo-diphosphineplatinum-closo-monocarbaborane complexes [Pt(L–L)(closo-CB11H12)][CB11H12][L–L =(C6H11)2P(CH2)3P(C6H11)2, 3a, But2P(CH2)3PBut2, 3b; But2P(CH2)2PBut23c; or But2PCH2C6H4CH2PBut2, 3d] in which the co-ordinated closo-CB11H12 ligand is strongly bond to platinum via two exo-polyhedral three-centre two-electron (Pt ⋯ H ⋯ B) bridges. These complexes are fluxional in solution at room temperature. A single-crystal X-ray diffraction study of 3c confirmed the bonding mode of the dodecarboraneligand. Complex 3c crystallizes in the monoclinic space group C2/c, a= 16.199(4), b= 16.564(5), c= 14.896(3)Å, β= 93.64(2)° and Z= 4. The final discrepancy index was R= 0.043, R′= 0.050 for 2838 independent reflections. The geometry around the platinum centre is distorted square planar with µ-H–Pt 1.90(8), Pt–B 2.342(8) and B-µ–H 1.23(8)Å. In contrast when the solvent is changed from ether to tetrahydrofuran (thf), complex 1b on protonation is converted into [PtMe(thf){But2P-P(CH2)3PBut2}][CB11H12]5. Complexes 3b-3d react with acetonitrile to yield [Pt(NCMe)2(L–L)][CB11H12]2[L–L = But2P(CH2)3PBut2, 6b; But2P(CH2)2PBut2, 6c; or But2CH2C6H4CH2But2, 6d]. Likewise 3b reacts with pyridine affording [Pt(NC5H5)2{But2P(CH2)3PBut2}][CB11H12]27. However C2H4, CO and PPh3 do not react readily with these complexes. The thf complex 5 reacts with deuteriated acetonitrile to form [PtMe(NCCD3){But2P(CH2)3PBut2}][CB11H12]8. Spectroscopic data for the new complexes are presented and discussed.

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J. Chem. Soc., Dalton Trans., 1991, 2769-2776
Article type
Paper

closo-Monocarbaboranes as ligands for transition metals: synthesis and reactivity of exo-diphosphineplatinum-closo-monocarbaborane complexes; structure of [Pt{But2P(CH2)2PBut2}(closo-CB11H12)][CB11H12]

G. S. Mhinzi, S. A. Litster, A. D. Redhouse and J. L. Spencer, J. Chem. Soc., Dalton Trans., 1991, 2769
DOI: 10.1039/DT9910002769

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