Investigating the reactivity of neutral water-soluble Ru(ii)–PTA carbonyls towards the model imine ligands pyridine and 2,2′-bipyridine

Abstract

The reactivity of selected Ru(ii)-PTA carbonyls with potentially labile ligands (i.e. H2O, dmso and/or Cl) towards the model imine ligands pyridine and 2,2′-bipyridine was investigated, yielding several neutral and cationic water-soluble derivatives.

Stereoisomeric Control in [RuCl2(PTA)2(2L)] Complexes (2L=2py or bpy): From Theoretical Calculations to a 2+2 Metallacycle of Pyridylporphyrins

“…[70] The relative position of Cl and py in this ranking is somehow controversial, where the RuÀ P bond trans to Cl in 2 is slightly shorter than those trans to py in 6 and 7 (Table 1 and Table 2), but the 1 c values of the same RuÀ P bonds follow the opposite order, suggesting that PTA prefers to bind trans to py than to Cl. Since thus far in none of the four neutral Ru(II)-PTA compounds containing Cl and pyridine PTA was found trans to Cl, [40] we believe that the 1 c parameter is more accurate in describing the binding preferences of these ligands; vi) the different geometrical preferences of [RuCl 2 (PTA) 2 (2 L)] complexes (2 L = 2py or bpy) can thus be explained mainly in terms of trans-influence (i. e. the stronger trans-influencing ligands PTA and bpy prefer to avoid being mutually trans). In addition, for bpy the steric constraints have also to be considered; vii) The orientation of the pyridine rings is mainly dictated by steric considerations.…”

“…In recent years we have actively investigated the chemistry of Ru(II)‐PTA compounds, preparing new species and finding systematic trends [6,36–40] . In particular – with the aim of preparing water soluble conjugates and metal‐mediated assemblies – we systematically explored the preparation of Ru(II)‐PTA derivatives with the imine ligands pyridine (py) and 2,2′‐bipyridine (bpy), [36,40] used as models for monodentate pyridyl‐linkers (e. g. 4,4′‐bpy or pyridylporphyrins) and for chelating diimine linkers, such as 4′‐methyl‐2,2′‐bipyridine‐4‐carboxylic acid (bpyAc) and 2‐(2′‐pyridyl)pyrimidine‐4‐carboxylic acid (cppH) (Figure 1), respectively [41–43] …”

“…Whereas there are very few examples of Ru(II)‐PTA coordination compounds in the literature with monodentate pyridine or azole ligands, [40] i. e. not included in polydentate moieties, [12,44–49] those with chelating diimine ligands are relatively more abundant. Stereoisomeric derivatives such as mer ‐ and fac ‐[Ru(bpy)Cl(PTA) 3 ](PF 6 ), and cis ‐ and trans ‐[Ru(bpy) 2 (PTA) 2 ](PF 6 ) 2 were prepared by us and by Romerosa and co‐workers [36,50–52] .…”

“…[2,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] In recent years we have actively investigated the chemistry of Ru(II)-PTA compounds, preparing new species and finding systematic trends. [6,[36][37][38][39][40] In particular -with the aim of preparing water soluble conjugates and metal-mediated assemblies -we systematically explored the preparation of Ru(II)-PTA derivatives with the imine ligands pyridine (py) and 2,2'-bipyridine (bpy), [36,40] used as models for monodentate pyridyl-linkers (e. g. 4,4'-bpy or pyridylporphyrins) and for chelating diimine linkers, such as 4'-methyl-2,2'-bipyridine-4-carboxylic acid (bpyAc) and 2-(2'-pyridyl)pyrimidine-4-carboxylic acid (cppH) (Figure 1), respectively. [41][42][43] Whereas there are very few examples of Ru(II)-PTA coordination compounds in the literature with monodentate pyridine or azole ligands, [40] i. e. not included in polydentate moieties, [12,[44][45][46][47][48][49] those with chelating diimine ligands are relatively more abundant.…”