ChemInform Abstract The alkenyl complexes (III), (V), (VI) (X-ray analysis; space group C2/c, Z=2), (VIII) and (IX), and (XII) are obtained by reactions of the phosphino enolate complexes (I), (IV), (VII) and (XI), respectively, with the acetylenedicarboxylate (II) according to the scheme. The tendency to form trans products decreases on going from Ni(II) to Pt(II). Isomerization reactions of the new phosphino alkenyl ligands are shown to occur in the complexes (IX) and (XII) giving the bis(alkyl) complex (X) (C2/c, Z=4) as a l-cis isomer and the P,O-chelate complex (XIII).

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Chlorodiphenylphosphine reacts with m-[MjPh2PCH=C(0)Phj2] (M = Ni (1), Pd (2), Pt (3)) to afford the complexes cis-[MCl2jPh2PCH=C(Ph)OPPh2j] (4-6, respectively), resulting from selective coupling of the oxygen atom of the enolate with phosphorus. Phosphorus double functionalization is achieved in the reaction of dichlorophenylphosphine with [(C N)Pd-(Ph2PCH=C(6)Phj] (CN = o-C6H"CH2NMe2 (7), C10H8N (8)) in the presence of pyridine, affording m-[PdCl2-|Ph2PCH=C(Ph)OP(Ph)(o-C6H4CH2NHMe2)!]Cl ( 9) and m-[PdCl2|Ph2PCH=C(Ph)OP(Ph)(CH2C9H6NH)|]Cl (10), respectively. These constitute the first examples of coupling reactions between a phosphorus atom and a transition-metal-bound carbon atom of a cyclometalated ligand. The new P P~N ligands are formed in a diastereoselective reaction and behave as P,P chelates to palladium. Compounds 9 and 10 are readily hydrolyzed in alkaline solutions, affording the oxodiarylphosphoranido complexes m-[Pd(Ph2PCH=C(0)Ph|(PhP(0)(o-C6H4CH2NMe2)|] (11) and rii-[Pd¡Ph2PCH==C(0)Ph|{PhP(0)-(CH2C9H6N)j] ( 12), respectively. The molecular structure of 12-CHC13 has been determined by X-ray diffraction: triclinic, space group , with Z = 2,a= 10.749 (5) A, b = 12.285 (3) A, c = 14.022 (5) A, a = 70.61 (2)°, ß = 86.80 (3)°, y = 81.54 (3)°, and V = 1727.8 A3. The structure has been refined for the 2612 reflections with F02 5> 3a(Ff) to R = 0.057 and Rw = 0.067.The coordination of the palladium deviates from the ideal planar geometry mainly because of the lack of flexibility of the P,N chelate, which prevents the nitrogen atom from occupying a position in the coordination plane. This also leads to a somewhat elongated Pd-N bond (Pd-N = 2.207 (7) A). All complexes were characterized by elemental analysis, IR spectroscopy, and and 31P('H) NMR spectroscopy.

Reactions between tetrahedral mixed-metal clusters HMCosfCO^[M = Fe (la), M = Ru (lb)] and trimethylamine IV-oxide have led to the formation of the amine-substituted clusters HMCo3(CO)11(NMe3) [M = Fe (2a), M = Ru (2b)] in high yields. 69Co NMR and IR spectroscopy were used to study the site selectivity of these reactions and indicate that substitution of the amine for the CO ligand takes place preferentially at one of the cobalt atoms. Clusters 2 are labile in solution and transform in the corresponding anions [Me3NH] [MCoslCO)^], owing to decoordination of the amine. Substitution reactions of the amine with other 2e donor ligands (PPh3, SEt^) were also studied. Disubstituted clusters were prepared under mild conditions and the very labile HMCo3(CO)i0(NMe3)2, in which two cobalt atoms carry each an amine ligand, was characterized by 59Co NMR spectroscopy. The structure of 2b has been determined by X-ray diffraction: space group Pna21 with a = 16.877 (5) A,b = 10.296 (2) A, c = 11.946 (2) A, aß = y = 90°, and Z = 4. The structure was refined to R = 0.026 and R" = 0.035 on the basis of 1471 reflections having F1 2 > 3 (F02). The cluster has a tetrahedral structure and the amine is axially bonded to a basal cobalt atom. "Numbers in parentheses are estimated standard deviations in the least significant digits. Table III. Selected Bi Co(2)-Co(l)-Ru 61.49 (4) Co(3)-Co(l)-Ru 61.46 (4) Co(l)-Co(2)-Ru 61.42 (5) Co(3)-Co(2)-Ru 61.63 (4) Co(l)-Co(3)-Ru 61.45 (4) Co(2)-Co(3)-Ru 61.69 (4) Co(l)-Ru-Co(2) 57.09 (4) Co(l)-Ru-Co(3) 57.09 (4) Co(2)-Ru-Co(3) 56.68 (4) Co(l)-Co(3)-Co(2) 60.23 (5) Co(l)-Co(2)-Co(3) 60.20 (5) Co(2)-Co(l)-Co(3) 59.58 (4) Ru-Co(l)-N(l) 175.9 (3) Ru-Co(l)-C(l) 81.8 (4) Ru-Co(l)-C(2) 82.4 (3) Ru-Co(l)-C(4) 85.1 (3) Ru-Co(l)-H 84 (3) Ru-Co(2)-C(l) 80.2 (3) Ru-Co(2)-C(3) 84.5 (3) Ru-Co(2)-C(5) 76.4 (4) Ru-Co(2)-C(6) 176.2 (3) Ru-Co(2)-H 84 (3) Ru-Co(3)-C(2) 81.6 (3) Ru-Co(3)-C(3) 84.0 (1) Ru-Co(3)-C(7) 75.6 (4) Ru-Co(3)-C(8) 175.5 (3) Ru-Co(3)-H 87 (3) Co(l)-Ru-C(9) 99.1 (3) Co(l)-Ru-C(10) 99.8(4) Co(l)-Ru-C(ll) 160.0 (3) Co(2)-Ru-C(9) 153.7 (3) Co(2)-Ru-C(10) 101.8 (4) Co(2)-Ru-C(U) 106.4 (4) Co(3)-Ru-C(9) 102.4 (3) Co(3)-Ru-C(10) 153.8 (4) Co(3)-Ru-C(U) 105.4 (3) Co(l)-Co(2)-C(l) 48.3 (3) Co(l)-Co(2)-C(3) 111.4 (3)°N umbers in parentheses are the least significant digits. d Angles (deg) of 2b°C o(l)-Co(2)-C(5) 126.1 (4) Co(l)-Co(2)-C(6) 119.3 (3) Co(l)-Co(2)-H 42 (3) Cp*2Ca0i-OC)2(OC)-2.15 (4.13, 1.64)" (4.07, 1.66)" 22 Cr(mes) "The values for the ring and methyl protons, respectively, of the mesitylene group. 2-transition-metal complexes that might serve either as precursors to or as models of these nonmolecular solids have been limited to O-bound (primarily alkoxide) species,7 and facile ligand exchange or loss can make controlling the composition of these systems difficult.8