Journal of Organometallic Chemistry 637 – 639 (2001) 691 – 697 www.elsevier.com/locate/jorganchem Synthesis, X-ray, spectroscopic and a preliminary Suzuki coupling screening studies of a complete series of dppfMX 2 (M = Pt, Pd; X = Cl, Br, I) Thomas J. Colacot a, *, Hu Qian a , Raymundo Cea-Olivares b , Simon Hernandez-Ortega b a Precious Metals Diision, Organometallic Chemicals and Catalysts Deelopment, Johnson Matthey, 2001 Nolte Drie, West Deptford, NJ 08066, USA b Instituto de Quı ´mica, Uniersidad Nacional Auto ´noma Me ´xico Circuito Exterior, Ciudad Uniersitaria, Mexico D.F. 04510, Mexico Received 9 April 2001; received in revised form 1 May 2001; accepted 2 May 2001 Abstract A complete series of dppfMX 2 (M=Pt, Pd; X =Cl, Br, I) compounds have been synthesized using different routes, and characterized fully. The synthesis of dppfPdI 2 has been achieved by reacting Pd(COD)Cl 2 with dppf in the presence of NaI. X-ray structures of dppfPdBr 2 and dppfPdI 2 have also been reported for the first time in this study. A preliminary Suzuki coupling screening study reveals that dppfPdX 2 compounds are superior to the conventional Ph 3 P-based catalysts and bidentate phosphine-based ligands. Reactions carried out under in situ conditions also gave a similar trend, but their respective activities were much lower than that of the fully formed catalysts. © 2001 Elsevier Science B.V. All rights reserved. Keywords: 1,1-Bis(diphenylphosphino)ferrocene; Suzuki coupling; NMR; X-ray; Pt and Pd complexes of dppf 1. Introduction The applications of 1,1-bis(diphenylphosphino)ferro- cene, dppf, and related ligands in C–C and C–het- eroatom coupling reactions have been reviewed very recently [1]. A couple of years ago, our laboratory had reported the syntheses and X-ray characterization of dppfPtI 2 and dppfPtPh 2 [2]. Interestingly, for both these complexes, the PPtP bite angles (Fig. 1) were larger than that of the reported structure of dppfPtCl 2 [3]. This was quite unexpected, as the steric bulk of the X 2 groups in (PP)PtX 2 (PP =bidentate phosphine) should theoretically decrease the PPtP bite angles. In Pd chemistry, about 15 years ago, Hayashi reported that dppfPdCl 2 behaved in a far superior manner than the conventional mono- and bidentate phosphines in their C – C coupling reactions involving a Grignard or zinc reagent [4]. The remarkable success of this catalyst was attributed to its larger PPdP bite angle (99.07°), and is referred to as ‘magic catalyst’ by Gan and Hor in the book, Ferrocenes [5]. However, a recent study from Hayashi’s laboratory suggested that smaller XPdX bond angles might be more important than the larger bite angles [6]. Since Pt is not a good system to study the C–C coupling reactions, we decided to synthesize a complete series of dppfMX 2 (M =Pt, Pd; X =Cl, Br, I) and systematically compare the catalytic activities of these complexes as a function of their bite angles and XPdX bond angles. This study also reports the X-ray crystal structures of dppfPdX 2 (X =Br, I), in order to obtain complete data on these series. Fig. 1. Bite angles of dppfPtX 2 (X =Cl, I, Ph) complexes, a compari- son. * Corresponding author. Tel.: +1-609-384-7185; fax: +1-609-384- 7035. E-mail address: colactj@jmusa.com (T.J. Colacot). 0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII: S0022-328X(01)00981-0