M−P versus MM Bonds as Protonation Sites in the Organophosphide-Bridged Complexes [M 2 Cp 2 (μ-PR 2 )(μ-PR‘ 2 )(CO) 2 ], (M = Mo, W; R, R‘ = Ph, Et, Cy) † (original) (raw)
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Synthesis and protonation of mixed diphosphorus ligand-bridged derivatives of di-iron nonacarbonyl
Polyhedron, 1993
Reaction of the di-iron heptacarbonyl compounds [Fe2(p-CO)(CO)&-R2PCH,PR2)2] (R = Me or Ph) with a range of diphosphorus or diarsenic ligands under photochemical conditions affords the ligand-bridged pentacarbonyl derivatives [Fez@-CO)(CO),(~-Me2PCH2PMe2)(p-L-L)] [L-L = (MeO)2PN(Et)P(OMe)2 or (EtO)2PN(Me) P(OEt)2] and [Fe2(~-CO)(CO)4(~-Ph2PCH2PPh&~-L-L)] [L-L = Me2PCH2PMe2, Ph2PN(Et)PPh2, Ph,AsCH,AsPh, (MeO),PN(Et)P(OMe), and (EtO)2PN(Me)P(OEt)2] in good yield. Treatment of these mixed ligand-bridged complexes with the protic acids HBF4 -Et20 or CF,COOH leads exclusively to the formation of the hydride-bridged species
Journal of Organometallic Chemistry, 1989
A series of phosphido-bridged heterodinuclear complexes has been prepared by the low temperature reaction of the labile chain complexes rrans-[Pd{m-(CO)},(PhCN),] (m = Cr, MO, W(CO),Cp; Mn(CO),) with 3 molar equivalents of PCy,H or PPh,H. The crystal structures of [Cp(CO),Mo(p-PCy,)Pd(PCy,H),] and [(CO),Mn(~-PCyz)P6~PCy2H)z] compounds were determined: Mo-Pd 2.916(2) A and Mn-Pd 2.689(2) A. Interest in the chemistry of phosphido-bridged heterometallic complexes has steadily increased since the first report of such complexes [l]. We have recently shown that complexes containing electron-rich M(p-PR,)Pt units may be prepared by the reaction of trinuclear mixed-metal chain complexes of the type trans-[Pt{M(CO),Cp}2(PhCN),1 (M = MO, W; Cp = q-C,H,) with secondary phosphines PR,H (R = Ph, Cy; Cy = CC ,H,,) [2]. We sought to extend this method to the synthesis of heterobimetallic complexes in which a palladium-transition metal bond would be supported by a bridging phosphido ligand. The labile chain complexes truns-[Pd(m(CO)},(PhCN),] 131 were treated in situ with 3 molar equivalents of PCy,H or PPh,H (eq. 1). The reactions proceed by nucleophilic displacement of the labile benzonitrile ligands, followed by oxidative-addition of the P-H bond across a heterometallic bond. The reactivity of PPh,H is generally greater than that of PCy,H.
…, 2002
The novel P-coordinated diphenyl(phenylethynyl)phosphine complexes [Cp*MCl 2 (PPh 2 Ct CPh)] [M) Rh 1, Ir 2] have been prepared by the bridge splitting of [Cp*MCl 2 ] 2 with PPh 2 Ct CPh. Treatment of 1 and 2 with AgTfO and PPh 2 CtCPh affords the corresponding cationic compounds [Cp*MCl(PPh 2 CtCPh) 2 ](OTf) [M) Rh 3, Ir 4, OTf) triflate], respectively. The analogous neutral Ru(II) derivative [Cp*RuCl(PPh 2 CtCPh) 2 ] 5 has been obtained by reaction of PPh 2 CtCPh and the binuclear complex [Cp*RuCl 2 ] 2 in the presence of Zn as the reductor. The molecular structures of 1 and 3-5 have been determined by single-crystal X-ray diffraction. The alkynyl fragments in cations 3 and 4 and in the neutral ruthenium derivative 5 are eclipsed, but the C R ‚‚‚C R interligand distances are longer than the minimal separation necessary (3.2-3.4 Å) to promote alkynyl coupling. The reactivity of these mono (1, 2) and bis[diphenyl(phenylethynyl)phosphine] (3-5) complexes toward [cis-Pt(C 6 F 5) 2 (THF) 2 ] has been explored. Treatment of 1 with 1 equiv of [cis-Pt(C 6 F 5) 2 (THF) 2 ] in CH 2 Cl 2 affords the doubly chloride bridged [(PPh 2 CtCPh)Cp*Rh(µ-Cl) 2 Pt(C 6 F 5) 2 ] 6. In contrast, the analogous iridium derivative [Cp*IrCl 2 (PPh 2 CtCPh)] 2 reacts with [cis-Pt(C 6 F 5) 2 (THF) 2 ], leading to a mixture of isomers [(PPh 2 CtCPh)Cp*Ir(µ-Cl) 2 Pt(C 6 F 5) 2 ] 7a and [Cp*ClIr(µ-Cl)(µ-κP:η 2-PPh 2 CtCPh)Pt(C 6 F 5) 2 ] 7b (7a/7b ≈ 2.5:1). Similar cationic [(PPh 2 CtCPh)Cp*M(µ-Cl)(µ-κP:η 2-PPh 2 CtCPh)Pt(C 6 F 5) 2 ](OTf) [M) Rh 8, Ir 9] and neutral [(PPh 2 CtCPh)Cp*Ru(µ-Cl)(µ-κP:η 2-PPh 2 CtCPh)Pt(C 6 F 5) 2 ] 10 hetero-bridged complexes are formed by treatment of the bis[diphenyl(phenylethynyl)]phosphine (3-5) complexes with [cis-Pt(C 6 F 5) 2 (THF) 2 ] in CH 2 Cl 2. The structure of 10 has been confirmed by a single-crystal X-ray diffraction analysis.
Organometallics, 2007
Square planar neutral dimethyl and cationic allyl complexes of palladium with the electronically nonsymmetric diphenylphosphinomethyl-and pyridyl-N-heterocyclic carbene ligands have been synthesized and characterized. The products from the protonation of the dimethyl complexes with 1 equiv of acid at low temperatures are monomethyl cations, the exact nature of which is dependent on the type of ligand; in pyridine-carbene complexes the Pd-Me bond cleaved is trans to the carbene, while for the phosphinocarbene complexes it is trans to the phosphine. Density functional calculations suggest that protonation in these complexes occurs directly at the methyl ligands and that the site of protonation determines the selectivity of Pd-Me cleavage. For the pyridine-carbene complexes there is a clear preference for protonation trans to the carbene. For phosphino-carbene complexes, however, the site of protonation depends on the steric bulk of the N-heterocyclic carbene ligand. Protonation trans to carbene is favored with small substituents (H, Me), but the bulky 2,6-Pr i 2 C 6 H 3 susbstituent induces protonation trans to the phosphine, as is seen experimentally.