www.elsevier.nl/locate/jorganchem Journal of Organometallic Chemistry 598 (2000) 248 – 253 Synthesis, structure and coordination chemistry of mono- and bis-heterocyclic-ferrocenyl derivatives Christian J. Isaac a , Clayton Price a , Benjamin R. Horrocks a , Andrew Houlton a, *, Mark R.J. Elsegood b , William Clegg b a Department of Chemistry Uniersity of Newcastle upon Tyne, Newcastle upon Tyne NE17RU, UK b Department of Chemistry, Crystallography Laboratory, Uniersity of Newcastle upon Tyne, Newcastle upon Tyne NE17RU, UK Received 31 July 1999; received in revised form 21 November 1999 Abstract The heterocyclic-ferrocenyl derivatives, 1,1-bis(5-phenanthridine)ferrocene (1) and [Pd{( 5 -C 5 H 5 )Fe( 5 -C 5 H 3 (phenanthro- line))}Cl] (2), have been prepared and characterised by single-crystal X-ray analyses. These confirm that in 1 the substitution at the heterocycle is ortho to the nitrogen atom of the phenanthridine while for 2 ortho -metallation of the ferrocenyl group is observed in addition to chelation of the Pd(II) by the phenanthroline moiety. © 2000 Elsevier Science S.A. All rights reserved. Keywords: Ferrocenyl; Heterocyclic; Palladium 1. Introduction The attachment of aromatic heterocycles, such as bipyridyl or phenanthroline, to the ferrocenyl group has been one strategy for locating a metal binding site in close proximity to a redox-active moiety [1–3]. Com- plexation reactions with Pd [2] and Ru [2] have been reported for such derivatives with binding involving the nitrogen donor atoms, though additional binding can also occur, particularly in the former case, through cyclometallation. Such reactions have often been re- ported for dimethylaminomethyl-substituted ferrocenyl derivatives [4]. Alternative applications for heterocyclic-ferrocenyl derivatives include the design of redox-active com- pounds for probing DNA structure and uses for com- pounds that exhibit either covalent or non-covalent binding have been described [5–7]. We are interested in the synthesis of such compounds and here report the preparation, electrochemical behaviour and the molecu- lar and crystal structure of a novel bis-substitu- ted derivative 1,1-bis(5-phenanthridine)ferrocene and also a ferrocenyl analogue, [Pd{( 5 C 5 H 5 )Fe( 5 C 5 H 3 - (C 12 H 7 N 2 ))}Cl], of the DNA-nicking palladium com- plexes of general type [PdCl(2-phenyl-1,10-phenanthro- line)] [8,9]. 2. Results and discussion 2.1. Syntheses 1,1-Bis(5-phenanthridine)ferrocene was prepared by the method reported by Butler for 2-ferrocenyl-1,10- phenanthroline and other heterocyclic derivatives [1,2]. This involves the initial formation of a suspension of mono/dilithioferrocene, generated by reaction of fer- rocene with n -butyllithium, with subsequent addition of the appropriate heterocycle under N 2 . Subsequent work up is in air to achieve oxidation of the expected dihydro intermediates [10], after which the crude mixture is then separated by column chromatography on silica to af- ford the pure product(s) [1,2]. The reaction yielded a mixture of ferrocene and unreacted phenanthridine along with three additional products as determined by TLC. Compared with the cases of 1,10-phenanthroline and bipyridyls [1,2], the reaction with phenanthridine gave a poorer overall yield and the major product was the bis-substituted * Corresponding author. Fax: +44-191-222-6929. E-mail address: andrew.houlton@ncl.ac.uk (A. Houlton) 0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved. PII:S0022-328X(99)00717-2