Different coordinating behaviour of the imino-phosphoranes Ph3PξNC(O)CH2Cl and Ph3PξNC(O)-2-NC5H4 towards MII complexes (M=Pd, Pt)

Synthesis, Structure, Reactivity, and Catalytic Activity of C,N‐ and C,N,N‐Orthopalladated Iminophosphoranes

“…The 31 P{ 1 H} NMR spectra of 11 and 12 show singlet signals at δ = 51.88 ppm in both cases (the signal of 12 shows the expected 195 Pt satellites), and these signals are strongly deshielded with respect to their position, not only in the free ligand (δ = 23.89 ppm) but also in the N,N-bonded complexes (δ Ϸ 34 ppm). [30] The position of this resonance is similar to that found in other recently described cyclopal-ladated derivatives in which the metallated iminophosphorane behaves as a C,N-chelating group. [37] Finally, the 13 C{ 1 H} NMR spectrum of 11 shows signals corresponding to the presence of all the expected functional groups, and confirms the structure proposed in Scheme 2.…”

“…[46] These two facts indicate that the iminic Natom is coordinated to the metal centre. [30] The 1 H NMR spectra of 11 and 12 show similar patterns, and unambiguously reveal the presence of the cyclometallated [M(C 6 H 4 -2-PPh 2 =N-)] unit. Thus, four different signals assigned to the protons of the C 6 H 4 unit can be observed at δ = 7.00, 7.13, 7.28 and 8.10 ppm in complex 11 and at δ = 6.95, 7.05, 7.23 and 8.02 ppm in 12, with the signal at δ = 8.02 ppm showing 195 Pt satellites, as well as signals corresponding to the pyridine group.…”

“…The reaction of Pd(OAc) 2 [30] never resulted in a metallated compound. The obvious difference in reactivity with that reported here comes from the reaction conditions: the processes performed at room temperature or at a low reflux temperature (CH 2 Cl 2 /acetone) give coordination compounds, [30] while those performed in harsh conditions (refluxing 2-methoxyethanol) give the metallated derivatives.…”

“…In the case of Pd, mixtures of the corresponding cis-and trans-[Cl 2 Pd(N-ligand) 2 ] derivatives were obtained; [29,30] in the case of platinum only decomposition to black Pt 0 was observed. Due to the lack of reactivity of these iminophosphoranes, they were not further investigated.…”

“…In this context, we have recently reported some aspects of the chemistry of the α-stabilized iminophosphoranes Ph 3 tate or chelate bidentate ligands towards Pd II and Pt II complexes using different donor atoms. [29,30] However, the synthesis of orthometallated aryl complexes derived from iminophosphoranes is still scarcely represented, as well as the properties of the resulting complexes (reactivity, catalytic performance), [31][32][33][34][35][36] although very recently relevant contributions have appeared in the literature. [37,38] With the aim of expanding the scope of this type of orthometallated derivatives, and also to gain more insight into their chemical behaviour, we have studied the reactivity of several iminophosphoranes towards Pd II and Pt II metallating reagents.…”