Chattopadhyay, Surajit ; Sinha, Chittaranjan ; Choudhury, Suranjan Bhanja ; Chakravorty, Animesh (1992) Synthesis and structure of binuclear thioazobenzene pallada-cycles and their reaction with m-chloroperbenzoic acid: formation and structure of dinuclear azophenolates Journal of Organometallic Chemistry, 427 (1). pp. 111-123. ISSN 0022-328X
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Official URL: http://linkinghub.elsevier.com/retrieve/pii/002232...
Related URL: http://dx.doi.org/10.1016/0022-328X(92)83210-9
Abstract
The cyclopalladation of 1,3-bis(2-thioazobenzene)propane (L1H2) and its methyl substituted derivative L2H2 affords complexes of the type LPd2Cl2 (where L represents L1 or L2 which have been characterised by spectroscopy and X-ray crystallography. The crystal structure of L1Pd2C2 has revealed that each azobenzene fragment along with its thioether sulphur acts in the tridentate (C,N,S) fashion and the fourth coordination position is occupied by a chloride ion. The complexes are thus of type [Pd(C,N,S)Cl]2, with a Pd Pd contact of 5.420(1) Å. The metallated carbon atom exerts a strong trans influence on the Pd---S bond. The reaction of LPd2Cl2 with am-chloroperbenzoic acid leads to smooth oxygen insertion into both the Pd---C bonds to give excellent yields of dinuclear azophenolato complexes o-LPd2Cl2 having the coordination sphere [Pd(O,N,S)Cl]2. The crystal structure of o-L1Pd2Cl2 is similar to that of L1Pd2Cl2 but with a somewhat longer Pd...Pd distance of 5.890(1) Å. The insertion reaction has a negative entropy of activation, in keeping with an associative transition state for the electrophilic incorporation of oxygen. Reduction of the azophenolato complexes with hydrazine hydrate affords the free azophenols (o-LH2) in high yields. Thus organometallic route to o-LH2 from LH2 is provided.
Item Type: | Article |
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Source: | Copyright of this article belongs to Elsevier Science. |
ID Code: | 6864 |
Deposited On: | 26 Oct 2010 05:19 |
Last Modified: | 31 Jan 2011 08:28 |
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