Base-Assisted Cyclometalation and Phosphorus−Carbon Bond Cleavage in (Arene)ruthenium(II) Complexes Containing Functionalized Iminophosphorane-Phosphine Ligands Ph₂PCH₂P{NP(X)(OR)₂}Ph₂ (X = O, S; R = Et, Ph)

Complexes [RuCl(η⁶-p-cymene)(κ²-P,X-Ph₂PCH₂P{NP(X)(OR)₂}Ph₂)][SbF₆] (X = O, R = Et (1a), Ph (1b); X = S, R = Et (2a), Ph (2b)) react with a stoichiometric amount of NaH, in THF at rt, to generate the neutral cyclometalated compounds [RuCl(κ²-P,C-Ph₂PCHP{NP(X)(OR)₂}Ph₂)(η⁶-p-cymene)] (X = O, R = Et (3a), Ph (3b); X = S, R = Et (4a), Ph (4b)), via selective deprotonation of the methylenic backbone of the coordinated iminophosphorane-phosphine ligands. Treatment of 3−4a,b with AgSbF₆, in CH₂Cl₂ at rt, affords the corresponding cationic species [Ru(κ³-P,C,X-Ph₂PCHP{NP(X)(OR)₂}Ph₂)(η⁶-p-cymene)][SbF₆] (X = O, R = Et (7a), Ph (7b); X = S, R = Et (8a), Ph (8b)) through the intramolecular O- or S-coordination of the free −Ph₂PNP(X)(OR)₂ fragment. Complexes 7−8a,b can also be prepared by reaction of the dicationic derivatives [Ru(η⁶-p-cymene)(κ³-P,N,X-Ph₂PCH₂P{NP(X)(OR)₂}Ph₂)][SbF₆]₂ (5−6a,b) with 1 equiv of NaH. Formation of complexes 3−4a,b and 7−8a,b proceeds, in all cases, in a diastereoselective manner. Phosphorus−carbon bond splitting has been observed upon treatment of complexes 1−2a,b, 3−4a,b, or 7−8a,b with an excess of NaH, in wet THF at rt, affording the novel phosphinito derivatives [Ru(κ²-C,X-CH₂P{NP(X)(OR)₂}Ph₂){κ¹-P-P(O)Ph₂}(η⁶-p-cymene)] (X = O, R = Et (10a); X = S, R = Et (11a), Ph (11b)). Protonation and methylation of 10−11a,b generates the cationic species [Ru(κ²-C,X-CH₂P{NP(X)(OR)₂}Ph₂){κ¹-P-P(OH)Ph₂}(η⁶-p-cymene)][BF₄] (X = O, R = Et (12a); X = S, R = Et (13a), Ph (13b)) and [Ru(κ²-C,X-CH₂P{NP(X)(OR)₂}Ph₂){κ¹-P-P(OMe)Ph₂}(η⁶-p-cymene)][CF₃SO₃] (X = O, R = Et (14a); X = S, R = Et (15a), Ph (15b)), respectively, via selective electrophilic addition at the Ph₂PO group. The structure of compounds [RuCl(κ²-P,C-Ph₂PCHP{NP(O)(OPh)₂}Ph₂)(η⁶-p-cymene)] (3b) and [Ru(κ²-C,S-CH₂P{NP(S)(OEt)₂}Ph₂){κ¹-P-P(O)Ph₂}(η⁶-C₆H₆)] (11a‘) has been determined by X-ray crystallography.