Reactivity of cyclopalladated compounds: VIII. Synthesis of cyclometallated compounds with an oxygen as the donor atom. Crystal and molecular structure of (8-methylquinoline-C,N)-(1-methoxynaphthalene-8-C,O)palladium(II) |
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Authors: | J. Dehand A. Mauro H. Ossor M. Pfeffer R.H. de A. Santos J.R. Lechat |
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Affiliation: | Laboratoire de Chimie de Coordination ERA 670 du CNRS, Université Louis Pasteur, 4 rue Blaise Pascal, F-67070 Strasbourg Cedex France;Instituto de Quimica e Fisica de Sao Paulo, Universidade de Sao Paulo Brazil |
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Abstract: | Treatment of 1-methoxynaphthalene (MXNH) with n-butyllithium in a diethyl ether/n-hexane solution gives 1-methoxynaphthalene-8-lithium (MXNLi) in 30% yield as an insoluble material. This compound reacts with PdCl2(SEt2)2 to give bis(1-methoxynaphthalene-8-C,O)palladium(II) (I)_and with PtCl2(SEt2)2 to give cis- and trans-(1-methoxynaphthalene-8-C,O)(1-methoxynaphthalene-8-C)(diethylsulfide)platinum(II) (II), which are non-rigid molecules in solution. With the cyclopalladated dimers [{)Cl2}2], MXNLi gives the palladobicyclic compounds: () (III). An X-ray diffraction study of compound IIIa where N∩N = 8-methylquinoline-C,N reveals the planarity of the molecule, shows that it has a cis configuration with respect to the PdC bonds, and confirms that the oxygen atom of MXN is bonded to palladium: PdO 2.236(4) Å. The geometry of IIIa is maintained in solution, whereas the corresponding compounds IIIb and IIIc in which N∩C is benzo[h]quinoline-9-C,N and N,N-dimethyl-1-naphthylamine-8-C,N, respectively, appear to be mixtures of cis and trans isomers in solution. With PMe2Ph I and II give trans-Pd(MXN)2(PMe2Ph)2 and cis-Pt(MNX)2(PMe2Ph)2, respectively, in which the methoxynaphthalene is bound to the metals via the 8-carbon of the naphthalene ring. Only one phosphine ligand adds to compounds IIIb and IIIc with displacement of the O → Pd bond. One carbon monoxide ligand can be added to the platinum compound II to give Pt(MXN)2(SEt2)CO which in solution exists as two isomers in equilibrium. |
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Keywords: | To whom correspondence should be addressed. |
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