Reactivity of alpha-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{Ph(2)PCH(AuPPh(3))C(O)Ph}](BF4) and of the nickel(II)-cobalt(II) paramagnetic complex cis-[Ni{Ph(2)PCH-C(-O)p-C6H4CH3}(2)]CoI2

The chemoselective reactivity of metal-coordinated phosphino enolates has been studied by the reactions of cis-[Ni{R'(2)PCHsic)C((sic)O)R}(2)] (R = Ph, p-C(6)H(4)Me, Me; R' = Ph, Pr-i, not all combinations) and [(C N)Pd{Ph(2)PCH(sic)C((sic)O)Ph}] (C N = o-C(6)H(4)CH(2)NMe(2), dmba or C10H8N, 8-mq) with different metal electrophiles. In the reaction of cis-[Ni{Ph(2)PCH(sic)C((sic)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{Ph(2)PCH(sic)C((sic)O)Ph}(2)] (3). However, reaction of cis-[Ni(R'2PCH(sic)C((sic)O)R}(2)] with anhydrous CoI2 afforded the heterobinuclear complexes cis-[Ni{R'2PCH(sic)C((sic)O)R}(2)]CoI2 (5a, R = Ph, R' = Ph; 5b, R = p-C(6)H(4)Me, R' = Ph; 5c, R = Me, R' = Ph; 7, R = Ph, R' = Pr-i) which contain the phosphino enolate ligand in an unusual chelating-bridging mu-eta(1)(O):eta(2)(P,O) coordination mode in a nonplanar NiO2Co unit. The magnetic properties of these complexes are discussed. The SHOP-type catalyst [Ni(Ph){Ph(2)PCH(sic)C((sic)O)Ph}(PPh(3))] also behaved as an oxygen-donor metalloligand toward CoI2 to give a paramagnetic Co(II) complex. In contrast, reaction of [(C N)Pd{Ph(2)PCH(sic)C((sic)O)Ph}] with [Au(PPh(3))](+) occurred with formation of [(dmba) Pd{Ph(2)PCH(AuPPh(3))C(O)Ph}](BF4) (4a) in which a C-enolate-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 H-1 NMR spectroscopy. The solid state structures of complexes 4a . 1/2C(7)H(8) and 5b . CH2Cl2 have been determined by single-crystal X-ray diffraction: 4a . 1/2C(7)H(8) crystallizes in the triclinic space group P (1) over bar with Z = 2 in a unit cell of dimensions a = 16.778(4) Angstrom, b = 14.269(5) Angstrom, c = 10.838(6) Angstrom, alpha = 79.27(4)degrees, beta = 71.59(3)degrees, and gamma = 72.68(2)degrees; 5 . CH2Cl2 crystallizes in the monoclinic space group P2(1)/n with Z = 4 in a unit cell of dimensions a = 12.940(1) Angstrom, b = 18.329(2) Angstrom, c = 18.495(2) Angstrom, and beta = 91.627(8)degrees. 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 . 1/2C(7)H(8)) and 3644 (5b . CH2Cl2) observed reflections to R and R(w) values of 0.0363 and 0.0406 (4a . 1/2C(7)H(8)) and 0.040 and 0.038 (5b . CH2Cl2), respectively.