Coupling of dichloroplatinum complexes with ethyne or butadiyne, catalyzed by CuI in the presence of Et 2 NH, leads to complexes of the types [Pt(CtCH) 2 L 2 ] (L 2 ) dppe (1), dppp (2); L ) PEt 3 (3)) and [Pt(CtCCtCH) 2 L 2 ] (L 2 ) dppp (4), dcpe (5); L ) PEt 3 (6)). Attempts to produce tetraplatinum species with ethynyl edges proved unsuccessful, but further coupling of the butadiynylplatinum complexes with [PtCl 2 L 2 ] produces the neutral molecular squares [Pt(µ-CtCCtC) 2 L 2 ] 4 (L 2 ) dppp (7), dcpe (8); L ) PEt 3 ( 9)). This two-step approach allows the synthesis of the unsymmetrical complexes [Pt 2 (µ-CtCCtC) 2 (PEt 3 ) 2 L 2 ] (L 2 ) dppp (10); dcpe ( 11)). The molecular structure of 7 reveals that each square has a puckered, butterflylike structure. These pack in a face-to-face manner, generating series of channels that accommodate several solvent molecules. Coupling of trans-[Pt(CtCCtC) 2 (PEt 3 ) 2 ] (6b) with [PtCl 2 L 2 ] (L 2 ) dcpe, dppp) leads to complexes assigned as neutral octaplatinum derivatives. The nitrogen-containing complexes [Pt(CtCC 5 H 4 N) 2 (dppp)] ( 14) and [Pt(CtCC 6 H 4 CN) 2 -(dppp)] (15) react with AgNO 3 to produce Pt 4 Ag 4 adducts.

Reactions of [PdX2(dppm)] (X = Cl, Br) with a range of Grignard reagents have been investigated. Diorganopalladium complexes of the type [PdR2(dppm)] were obtained in good yield with the bulky mesityl or trimethylsilylmethyl groups, provided the reactions were performed using high Grignard:Pd ratios in ether solution. With the smaller R groups Me, Et, Bu, and CH2Ph, only the halide-bridged A-frame complexes [Pd2R2(μ-X)(μ-dppm)2]+ were formed, irrespective of the reaction conditions. Mixtures of chloride- and bromide-bridged complexes were produced when [PdCl2(dppm)] was treated with RMgBr, so [PdBr2(dppm)] was used as the starting material in certain cases. The mesityl derivative [Pd2(C6H2Me3)2(μ-Br)(μ-dppm)2]+ could be obtained from the reaction of [PdBr2(dppm)] with 4 mol equiv of C6H2Me3MgBr in CH2Cl2 solution, but with Me3SiCH2MgCl mixtures of monomeric and dimeric complexes were obtained under these conditions. The A-frame complex [Pd2(CH2SiMe3)2(μ-Cl)(μ-dppm)2]+ was generated, however, by reaction of [Pd(CH2SiMe3)2(dppm)] with 1 mol equiv of HCl. The A-frames were isolated as their PF6 - salts. They were characterized by elemental analysis, NMR spectroscopy, and, in the case of [Pd2(C6H2Me3)2(μ-Br)(μ-dppm)2]PF6, X-ray crystallography. The molecular structure of the [Pd2(C6H2Me3)2(μ-Br)(μ-dppm)2]+ cation reveals that it adopts an elongated boat conformation, with the dppm CH2 groups lying on the same side of the Pd2P4 framework as the bridging bromide. With the smaller aryl Grignards PhMgBr, p-tolylMgBr, or o-tolylMgCl, the diarylpalladium species [PdAr2(dppm)] could be detected in solution at low temperatures but at ambient temperature reductive coupling of the aryl groups occurred and the palladium(I) complexes [Pd2X2(μ-dppm)2] were formed.

Reactions between diaminediaquaplatinum complexes [Pt(N∩N)(H2O)2]2+ and sodium ascorbate (NaHAsc) have been studied using 1H and 195Pt NMR spectroscopy. Mixtures of platinum ascorbate species were formed involving different binding modes of the ascorbate ligand, namely, [Pt(HAsc-O 3)(H2O)(N∩N)]+, in which a single ascorbate acts as a monodentate ligand, the bis(ascorbate)platinum complexes [Pt(HAsc-O 3)2(N∩N)] and [Pt(HAsc-O 3)(HAsc-C 2)(N∩N)], and [Pt(Asc-O 2,O 3)(N∩N)] and [Pt(Asc-C 2,O 5)(N∩N)], in which the ascorbate acts as a chelating ligand (N∩N = en, N,N-dmen, N,N‘-dmen, N,N,N‘,N‘-tmen; HAsc- = C6H7O6 -, Asc2- = C6H6O6 2-). The crystal structure of ascorbato-C 2,O 5-ethylenediamineplatinum(II) dihydrate, [Pt(Asc-C 2,O 5)(en)]·2H2O, was established by X-ray crystallography. A series of diphosphineplatinum complexes of the type [Pt(Asc-O 2,O 3)(P∩P)] (P∩P = dppm, dppe, dppp) was prepared from the corresponding [Pt(NO3)2(P∩P)] species. These have been characterized by elemental analysis and infrared and 1H and 31P{1H} NMR spectroscopies.

Reactions of [PtCl2(cod)] with the appropriate Grignard reagents produce [PtR2(cod)] (R = C6H5, C6H4CH3-4, C6H4CH3-2, CH2C6H5), which, on treatment with 1 mol equiv of HCl, yield the corresponding chloroplatinum complexes [PtClR(cod)]. The 2-tolyl compounds exhibit hindered rotation about the Pt−C bonds at ambient temperature, the barrier to rotation being greater in [PtCl(C6H4CH3-2)(cod)] than in the ditolyl derivative. The chloroplatinum compounds react with 1 mol equiv of dppm to give [PtClR(dppm)], which are in equilibrium with the A-frame complexes [Pt2R2(μ-Cl)(μ-dppm)2]Cl. The extent of dimerization depends on the nature of R, but in each case the A-frame complex could be obtained quantitatively by treatment of the solution with NH4PF6 or TlPF6. The structures of [Pt2R2(μ-Cl)(μ-dppm)2]PF6 (R = CH2C6H5, C6H4CH3-4) were determined by X-ray crystallography. In the benzyl derivative, one of the ortho hydrogens on each phenyl (benzyl) ring points towards the centroid of a dppm phenyl ring, and this may account for the low-frequncy signal associated with the ortho hydrogens in solution. The chloride-bridged A-frames could be converted to the corresponding hydride-bridged derivatives, [Pt2R2(μ-H)(μ-dppm)2]PF6 (R = C6H5, C6H4CH3-4, CH2C6H5), by treatment with NaBH4.