Reactivity of α-Phosphino Enolate Complexes of Nickel(II) and Palladium(II) toward Electrophilic Metal Centers. Synthesis and Crystal Structures of the Bimetallic Palladium(II)−Gold(I) Complex [(dmba)Pd{Ph₂PCH(AuPPh₃)C(O)Ph}](BF₄) and of the Nickel(II)−Cobalt(II) Paramagnetic Complex cis-[Ni{Ph₂PCH C( O)(p-C₆H₄CH₃}₂]CoI₂

Abstract

The chemoselective reactivity of metal-coordinated phosphino enolates has been studied by the reactions of cis-[Ni{R‘2PCH C( O)R}2] (R = Ph, p-C6H4Me, Me; R‘ = Ph, iPr, not all combinations) and [(C N)Pd{Ph2PCH C( O)Ph}] (C N = o-C6H4CH2NMe2, dmba or C10H8N, 8-mq) with different metal electrophiles. In the reaction of cis-[Ni{Ph2PCH C( O)Ph}2] (1a) with [PtCl2(COD)] (COD = 1,5-cyclooctadiene), a transmetalation of the P,O ligands was observed, yielding the known complex cis-[Pt{Ph2PCH C( O)Ph}2] (3). However, reaction of cis-[Ni{R‘2PCH C( O)R}2] with anhydrous CoI2 afforded the heterobinuclear complexes cis-[Ni{R‘2PCH C( O)R}2]CoI2 (5a, R = Ph, R‘ = Ph; 5b, R = p-C6H4Me, R‘ = Ph; 5c, R = Me, R‘ = Ph; 7, R = Ph, R‘ = iPr) which contain the phosphino enolate ligand in an unusual chelating-bridging μ-η1(O):η2(P,O) coordination mode in a nonplanar NiO2Co unit. The magnetic properties of these complexes are discussed. The SHOP-type catalyst [Ni(Ph){Ph2PCH C( O)Ph}(PPh3)] also behaved as an oxygen-donor metalloligand toward CoI2 to give a paramagnetic Co(II) complex. In contrast, reaction of [(C N)Pd{Ph2PCH C( O)Ph}] with [Au(PPh3)]+ occurred with formation of [(dmba)Pd{Ph2PCH(AuPPh3)C(O)Ph}](BF4) (4a) in which a Cenolate−Au bond has been formed while the P,O chelate has remained coordinated to palladium. This reaction generates a new stereogenic center, as also evidenced by 1H NMR spectroscopy. The solid state structures of complexes 4a·1/2C7H8 and 5b·CH2Cl2 have been determined by single-crystal X-ray diffraction: 4a·1/2C7H8 crystallizes in the triclinic space group P1̄ with Z = 2 in a unit cell of dimensions a = 16.778(4) Å, b = 14.269(5) Å, c = 10.838(6) Å, α = 79.27(4)°, β = 71.59(3)°, and γ = 72.68(2)°; 5·CH2Cl2 crystallizes in the monoclinic space group P21/n with Z = 4 in a unit cell of dimensions a = 12.940(1) Å, b = 18.329(2) Å, c = 18.495(2) Å, and β = 91.627(8)°. The structures have been solved from diffractometer data by direct and Fourier methods and refined by full-matrix least-squares methods on the basis of 7240 (4a·1/2C7H8) and 3644 (5b·CH2Cl2) observed reflections to R and R w values of 0.0363 and 0.0406 (4a·1/2C7H8) and 0.040 and 0.038 (5b·CH2Cl2), respectively.

An Oriented 1D Coordination/Organometallic Dimetallic Molecular Wire with AgPd Metal–Metal Bonds

“…Accordingly, the NCH 2 protons only show a doublet in the 1 H NMR spectrum as a result of coupling to the P atom. The O1C10 and N2C10 bond lengths of 1.273(9) and 1.353(9) Å, respectively, are consistent with C${^{\underline{.....}}}$ O and N${^{\underline{.....}}}$ C bond orders intermediate between single and double bonds 7. 9, 14…”

“…The latter selectivity also applies to late‐transition metals and opens an interesting route to (hetero)dimetallic complexes in which the PC carbon atom has become sp 3 hybridized 7. Although control of the stereochemistry at the PC carbon atom is possible,8 the generation of both the R and S ‐configured stereogenic P‐C centers is generally expected.…”

An Oriented 1D Coordination/Organometallic Dimetallic Molecular Wire with AgPd Metal–Metal Bonds

“…[7] Although control of the stereochemistry at the PC carbon atom is possible, [8] the generation of both the R and Sconfigured stereogenic P-C centers is generally expected.…”

“…The O1ÀC10 and N2ÀC10 bond lengths of 1.273(9) and 1.353 (9) , respectively, are consistent with CPO and NPC bond orders intermediate between single and double bonds. [7,9,14] A solution of 3 in THF was then treated with pure, acidfree AgSO 3 CF 3 in a 1:1 stoichiometry, and slow crystallization afforded high yields of a beige product 5·SO 3 CF 3 [Eq. (2)], which was shown by X-ray diffraction studies to be an unprecedented Ag-Pd coordination polymer (Figure 2 and see the Supporting Information).…”

Investigation of the reactivity of palladium(0) complexes with nitroso compounds: relevance to the palladiumphenanthroline-catalysed carbonylation reactions of nitroarenes

“…The insertion into the Pd C bond of unsaturated molecules might demonstrate a palladiumassisted transfer of the enolate moiety to substrates which would be unlikely to react in a metal-free reaction [22]. On the other hand, it has already been shown [23] that enolate complexes of palladium(II) react with organic electrophilic species to form new C C bonds.…”