Octahedral and trigonal-bipyramidal complexes of ruthenium(II) with bidentate phosphine ligands

Abstract

Six-and five-co-ordinate complexes of ruthenium(ir) with the unsymmetrical diphosphine ligand Ph2P(CH2)3PMe2 have been prepared. Phosphorus-31 n.m.r. spectroscopy indicates that octahedral complexes [RuCI,(P-P),],[RuH(CI)(P-P),], and [RuH(CO)(P-P),JCIO, (P-P = diphosphine ligand) have the all-trans arrangement with Me,P trans to Me,P and Ph2P trans t o Ph2P. The five-co-ordinate complexes [RuX(P-P),]BPh,, where X = CI or H, are not fluxional at room temperature and have a trigonal-bipyramidal structure with axial PMe2 groups and equatorial PPh, groups. Similar structures are proposed for analogous complexes of Ph,P(CH,),PMePh and of Ph2P(CH2),PPh2.

The Square Pyramidal Hydride Cation [RuH(dcpe)2]+, dcpe = Bis(dicyclohexylphosphino)ethane. Structures of [RuH(dcpe)2]+[BPh4]- and of the Zwitterionic {(η6-C6H5)BPh3}RuH(dcpe)

“…Special attention has been paid to five-coordinate complexes with a d 6 configuration of the metal center, particularly in view of their high reactivity arising from electronic and steric unsaturation. While ruthenium complexes of the type Ru(PR 3 ) 3 XY are relatively common, − it is only recently that a comparable number of examples of [MX(L 2 ) 2 ] + are known, where L 2 represents a chelating diphosphine and X a unidentate monoanionic ligand. − They possess a P 4 X donor set around the metal center and are frequently generated by dissociation of an anionic ligand Y - from saturated six-coordinate precursors. The readiness with which MXY(L 2 ) 2 complexes undergo such a ligand dissociation was found to depend on several factors such as the steric bulk and the electronic properties of the chelating diphosphine and the ligand X - , the ring size of the chelate formed, the solvent employed, or which of the two possible isomers ( cis or trans ) of the starting material is used.…”

“…The readiness with which MXY(L 2 ) 2 complexes undergo such a ligand dissociation was found to depend on several factors such as the steric bulk and the electronic properties of the chelating diphosphine and the ligand X - , the ring size of the chelate formed, the solvent employed, or which of the two possible isomers ( cis or trans ) of the starting material is used. To only briefly illustrate some of these points, trans -RuCl 2 (Ph 2 P(CH 2 ) 3 PPh 2 ) 2 was reported to react with NaBPh 4 or NaPF 6 in ethanol to give [RuCl(Ph 2 P(CH 2 ) 3 PPh 2 ) 2 ] + , while the methyl substituted derivative trans -RuCl 2 (Me 2 P(CH 2 ) 3 PMe 2 ) does not. ,, Likewise, RuBr 2 (dcpe) 2 (dcpe = bis(dicyclohexylphosphino)ethane) spontaneously dissociates a bromide ion upon dissolution in dichloromethane, whereas the dichloro derivative requires refluxing of the starting material in ethanol in the presence of a noncoordinating counterion . The effect of the chelate ring size may be inferred from the fact that trans- RuCl 2 (Ph 2 P(CH 2 ) n PPh 2 ) 2 reacts with NaPF 6 in refluxing ethanol to yield five-coordinate compounds when n = 3, , whereas no such reaction is observed for n = 2 …”

Five‐ and Six‐Coordinate Ruthenium(II) Complexes Containing the Bidentate Phosphane (−)‐N,N‐Bis(diphenylphosphanyl)‐(S)‐1‐phenylethylamine [(S)‐peap]: X‐ray Crystal Structure of the First 16‐Electron Ruthenium Complex Bearing a Four‐Membered Ring [RuCl{κ2‐P,P‐(S)‐peap}2][SbF6]·C2H4Cl2

“…All the data suggest the formation of only one diastereoisomer. In particular, the 31 P{ 1 H} NMR spectrum shows two pseudotriplets (A 2 X 2 spin system) at δ = 69.63 (P ax ) and 101.67 (P eq ) (t, 2 J P,P′ = 42.3 Hz)15 which are consistent with the formation of a sole diastereoisomer with a stereochemically rigid trigonal‐bipyramidal structure (TBP). This pattern remains unchanged over a wide temperature range (193 to 353 K) in dichloromethane or 1,2‐dichloroethane solution, indicating that a dynamic process involving an equilibrium between the two diastereoisomers Δ( S , S ) and Λ( S , S ) is unlikely.…”

Synthesis and characterization of binuclear platinum group metal complexes of novel hexadentate ligands .alpha.,.alpha.'-bis(bis(2-(diphenylphosphino)ethyl)amino)-p-xylene and .alpha.,.alpha.'-bis(bis(2-(diphenylarsino)ethyl)amino)-p-xylene

“…When the above reaction was conducted in refluxing benzene, polymeric products are formed. Complexes 1 and 2 are nonelectrolytes18 in DMF solvent (Table T h PXBDAA (21) (5) II). The presence of two bands in the r(Ru-Cl) region at 266 and 311 cm™1 in complex 1 and 321 and 350 cm™1 in complex 2 indicate a cis diposition of the two chlorides in the complexes.19…”