The first water-soluble tetraphosphorus ruthenium complex. Synthesis, characterization and kinetic study of its hydrolysis Maria Caporali a , Luca Gonsalvi a , Rustam Kagirov b , Vincenzo Mirabello a , Maurizio Peruzzini a, * , Oleg Sinyashin b , Piero Stoppioni c , Dmitry Yakhvarov b, ** a Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy b A.E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences, Arbuzov str., 8, 420088 Kazan, Russian Federation c Dipartimento di Chimica, Università degli Studi di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy article info Article history: Received 1 February 2012 Accepted 15 March 2012 Keywords: White phosphorus Kinetics Ruthenium Water-soluble complexes abstract Reaction of the water-soluble complex [CpRu(TPPMS) 2 Cl] (1) [TPPMS ¼ sodium salt of m-monosulfonated triphenylphosphine, Ph 2 P(m-C 6 H 4 SO 3 Na)] with 1 equiv of white phosphorus in the presence of TlPF 6 or AgBF 4 as chloride scavengers, yielded the stable hydrosoluble complexes [CpRu(TPPMS) 2 (h 1 -P 4 )]X (2) (X ¼ PF 6 , BF 4 ). Addition of water to DMF solutions of 2 causes hydrolysis ovf coordinated P 4 giving as main products complexes [CpRu(TPPMS) 2 (PH 3 )]X (3) (X ¼ PF 6 , BF 4 ) together with hydrogen and phos- phorous acid, H 3 PO 3 . The new complexes have been characterized by 1 H and 31 P NMR spectroscopy in solution. Kinetic data and activation parameters of the hydrolysis process are reported. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction The reactivity of white phosphorus, P 4 , towards different tran- sition metal complexes has been widely developed during the last decades [1e3]. Coordination of white phosphorus to a transition metal crucially changes the reactivity of the PeP bonds of the P 4 tetrahedron resulting in its activation. The following opening of white phosphorus cage leads to a variety of P n units that may be stabilized in the coordination sphere of transition metal complexes. The understanding of the factors ruling the selective activation of the P n units is of high interest, mostly because it could help to develop a chlorine-free method for the preparation of useful phosphorus compounds directly from white phosphorus [4]. Recently, it was found that some 16-electron ruthenium complexes may coordinate the intact P 4 molecule forming mono- and bimetallic compounds in good yields [5e7]. The high stability and availability of these complexes have allowed investigating the reactivity of coordinated P 4 towards a variety of different organic and inorganic reagents. The obtained results are particularly intriguing and show that the P 4 molecule in the monometallic [CpRu(PPh 3 ) 2 (h 1 -P 4 )]X (X ¼ PF 6 , OTf) and [CpRu(dppe)(h 1 -P 4 )] PF 6 complexes readily undergoes disproportionation with water under mild conditions leading to the corresponding complex bearing phosphine as ligand and free oxygenated phosphorus compounds [6a,b]. On the other hand, working with a bimetallic ruthenium complex, [{CpRu(PPh 3 ) 2 } 2 (m,h 1:1 -P 4 )](CF 3 SO 3 ) 2 and varying the excess of water, formation of H 3 PO 3 and polyphosphorus compou nds containing PeH and P-OH groups bridging the two metal centres were observed [7]. However, only few examples are mentioned in the literature [6,7] concerning the investigation of the reactivity of white phos- phorus towards water-soluble ruthenium complexes. The use of such complexes would help for the extraction of white phosphorus residues from aqueous environments and decrease the danger of P 4 dispersed in water, as it would not be harmful once coordinated to a metal centre. A beautiful example comes from the group of Nitschke [8], who recently demonstrated that P 4 can be seques- tered by a self-assembled tetrahedral capsule, which is formed in water by organic hydrophilic linkers and iron(II) ions. Within this system, P 4 becomes water-soluble and air-stable for indefinite time. In addition, the cage has the advantage to release P 4 at will. On the other hand, water-soluble ruthenium complexes such as 1 have been already successfully used to trap highly unstable phosphorus species such as phosphine oxide, H 3 PO, generated by electro- chemical activation of white phosphorus carried out in water/ ethanol mixture [9]. Our interest in this field also resides in the possibility to extract P 4 from an organic solvent (immiscible with water) to an aqueous phase as a possible way to clean organic waste from phosphorus * Corresponding author. Tel.: þ39 055 5225289; fax: þ39 055 5225203. ** Corresponding author. Fax: þ7 843 2732253. E-mail addresses: mperuzzini@iccom.cnr.it (M. Peruzzini), yakhvar@iopc.ru (D. Yakhvarov). Contents lists available at SciVerse ScienceDirect Journal of Organometallic Chemistry journal homepage: www.elsevier.com/locate/jorganchem 0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2012.03.019 Journal of Organometallic Chemistry 714 (2012) 67e73