Reaction of tri(2-furyl)phosphine with triosmium clusters: CeH and PeC activation to afford furyne and phosphinidene ligands Mohammad A. Rahman a , Noorjahan Begum b , Shishir Ghosh a , Md. Kamal Hossain a , Graeme Hogarth c , Derek A. Tocher c , Ebbe Nordlander b , Shariff E. Kabir a, * a Department of Chemistry, Jahangirnagar University, Savar, Dhaka-1342, Bangladesh b Inorganic Chemistry Research Group, Chemical Physics, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100 Lund, Sweden c Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK article info Article history: Received 19 August 2010 Received in revised form 14 September 2010 Accepted 17 September 2010 Available online 27 September 2010 Keywords: Trisomium clusters Tri(2-furyl)phosphine Carbonehydrogen and carbonephosphorus bond activation Furyne cluster Heteroaromatic ring rearrangement abstract Addition of tri(2-furyl)phosphine, PFu 3 , to [Os 3 (CO) 10 (m-H) 2 ] at room temperature gives [HOs 3 (CO) 10 (PFu 3 ) (m-H)] (1), while in refluxing toluene the same reactants afford [Os 3 (CO) 9 {m 3 -PFu 2 (C 4 H 2 O)}(m-H)] (2) resulting from orthometallatation of a furyl ring. Reaction of PFu 3 with [Os 3 (CO) 10n (NCMe) n ](n ¼ 0, 1, 2) affords the substituted clusters [Os 3 (CO) 12n (PFu 3 ) n ](n ¼ 1e3) (3e5), the phosphine ligands occupying equatorial position in all cases. Heating [Os 3 (CO) 11 (PFu 3 )] (3) in refluxing octane gives [Os 3 (CO) 9 (m 3 -PFu)(m 3 - h 2 -C 4 H 2 O)] (6) which results from both carbonehydrogen and carbonephosphorus bond activation and contains both m 3 -h 2 -furyne and furylphosphinidene ligands. All new clusters have been characterized by spectroscopic methods together with single crystal X-ray diffraction for 2, 3 and 6. Ó 2010 Published by Elsevier B.V. 1. Introduction Tri(2-furyl)phosphine, PFu 3 , has recently attracted the attention of organometallic chemists due to its increasing importance in transition metal catalysis [1e 7] since catalysts employing this ligand are often more active than traditional PPh 3 based catalysts. This difference is believed to be a consequence of the different electronic properties of PFu 3 over PPh 3 , as their Tolman cone angles (PPh 3 e 145  ; PFu 3 e 133  ) are quite similar. Thus, the electron-withdrawing nature of the 2-furyl ring is considered to be greater than that of the phenyl ring which makes the phosphorus a poor s-donor in PFu 3 relative to that of PPh 3 [8]. The transition metal carbonyl chemistry of thienyl and pyrrolyl-substituted phosphines has been extensively studied due to their relevance to the important hydrodesulfurization and hydrodenitrogenation processes [9e33]. In comparison, the chemistry of phosphines bearing furyl substituents is relatively unexplored. We have recently documented the reactivity of PFu 3 with dirhenium complexes, [Re 2 (CO) 10n (NCMe) n ](n ¼ 0, 1, 2), and here its behaviour closely parallels that of PPh 3 [34]. In contrast, at a triruthenium centre the two behave quite differently. Thus, it is known that [Ru 3 (CO) 11 (PPh 3 )] rearranges upon heating to afford a benzyne complex resulting from phosphorusecarbon and car- bonehydrogen bond activation [35,36]. In contrast, heating [Ru 3 (CO) 12n (PFu 3 ) n ] (n ¼ 1,2) affords the furenyl complex, [Ru 2 (CO) 6 (m-PFu 2 )(m-h 1 ,h 2 -C 4 H 3 O)] [37,38], resulting from both rutheniumeruthenium and phosphorusecarbon bond scission, while a similar thermolysis of [Ru 3 (CO) 9 (PFu 3 ) 3 ] in the presence of Me 3 NO affords [Ru 2 (CO) 5 (PFu 3 )(m-PFu 2 )(m-h 1 ,h 2 -C 4 H 3 O)] [38]. The chemistry of these diruthenium complexes has been extensively studied [37e39]. In a similar manner, the thermal rearrangement of [Ru 3 (CO) 9 (PPh 3 )(m-dppm)] [40] is quite different from that of [Ru 3 (CO) 9 (PFu 3 )(m-dppm)], the latter leading to formation of the furyne cluster [Ru 3 (CO) 7 (m-PFu 2 )(m 3 -h 2 -C 4 H 2 O)(m-H)(m-dppm)] [41]. It is thus clear that while PPh 3 and PFu 3 can be easily compared in simple mononuclear complexes, they likely behave quite differ- ently at multimetallic centres. With this in mind, we have now investigated reactions of PFu 3 with triosmium clusters, the results of which are presented herein. 2. Experimental All reactions were carried out under a nitrogen atmosphere using standard Schlenk techniques. Reagent-grade solvents were * Corresponding author. Tel.: þ88 02 7791033; fax: þ88 02 7791052. E-mail address: skabir_ju@yahoo.com (S.E. Kabir). Contents lists available at ScienceDirect Journal of Organometallic Chemistry journal homepage: www.elsevier.com/locate/jorganchem 0022-328X/$ e see front matter Ó 2010 Published by Elsevier B.V. doi:10.1016/j.jorganchem.2010.09.046 Journal of Organometallic Chemistry 696 (2011) 607e612