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The neutral square-planar complexes [Pt(RNH2)2(NHCO(t)Bu)2] (R = H, 1; Et, 2) and [Pt(DACH)(NHCO(t)Bu)2] (DACH = 1,2-diaminocyclohexane, 3) act as metalloligands and make bonds to closed-shell Tl(I) ions to afford one- and two-dimensional platinum-thallium oligomers or polymers based on heterobimetallic backbones. A series of heteronuclear platinum(II)-thallium(I) complexes have been synthesized and structurally characterized. The structures of the Pt-Tl compounds resulted from [Pt(RNH2)2(NHCO(t)Bu)2] and TlX [X = NO3(-), ClO4(-), PF6(-), and Cp2Fe(CO2)2(2-)] are dependent on both counteranions and the amine substituents. The compounds [Pt(NH3)2(NHCO(t)Bu)2Tl]X (X = NO3(-), 8; ClO4(-), 9) adopt one-dimensional zigzag chain structures consisting of repeatedly stacked [Pt(NH3)2(NHCO(t)Bu)2Tl]+ units, whereas [{Pt(NH3)2(NHCO(t)Bu)2}2Tl2]X2 (X = PF6(-), 10) consists of a helical chain. Compound 3 reacts with Tl+ to give [{Pt(DACH)(NHCO(t)Bu)2}2Tl](NO3) x [Pt(DACH)(NHCO(t)Bu)2] x 3 H2O (14) and one-dimensional polymeric [{Pt(DACH)(NHCO(t)Bu)2}2Tl2]X2 (X = ClO4(-), 15; PF6(-), 16). Reactions of [Pt(DACH)(NHCOCH3)2] with Tl+ ions afford one-dimensional coordination polymers [{Pt(DACH)(NHCOCH3)2}2Tl2]X2 (X = NO3(-), 17; ClO4(-), 18; PF6(-), 19). The polymeric [{Pt(DACH)(NHCOR')2}2Tl2]2+ (R = CH3, (t)Bu) complexes adopt helical structures, which are generated around the crystallographic 2(1) screw axis. The distance between the coils corresponds to the unit cell length, which ranges from 22.58 to 22.68 A. The platinum-thallium bond distances fall in a narrow range around 3.0 A. The complexes derived from [Pt(NH3)2(NHCO(t)Bu)2] are luminescent at 77 K. The trinuclear complexes [{Pt(RNH2)(NHCO(t)Bu)2}2Tl]+ do not emit at room temperature but are emissive at 77 K, whereas the polymeric platinum-thallium complexes containing 1,2-diaminocyclohexane are intensively luminescent at both room temperature and 77 K. The color variations are interesting; 15 exhibits intense yellow-green, 16 exhibits green, and 17-19 exhibit blue luminescence. The presence of bonding between platinum and thallium is supported by the short metal-metal separations and the strong low-energy luminescence of these compounds in their solid states.

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The monohydrido complex RuHCl(CO)(PiPr3)2 (1) reacts with 2-methyl-1-buten-3-yne to give Ru{(E)-CHCHC(CH3)CH2}Cl(CO)(PiPr3)2 (2) , which has been characterized by X-ray diffraction analysis. The coordination geometry around the ruthenium atom can be rationalized as a square pyramid with the α,β-unsaturated alkenyl ligand located in the apex. The ruthenium alkenyl separation is short (1.989(3) Å), suggesting a significant contribution of the zwitterionic resonance form [Ru+]CHCHC(CH3)CH2 - to the structure of 2. In agreement with this, complex 2 reacts with HBF4 to afford the carbene derivative [Ru{CHCHC(CH3)2}Cl(CO)(PiPr3)2]BF4 (3). The coordination number 6 for 2 can be achieved by addition of carbon monoxide. Thus, bubbling carbon monoxide through a hexane solution of 2 results in the formation of Ru{(E)-CHCHC(CH3)CH2}Cl(CO)2(PiPr3)2 (4). Complex 4 reacts with CH3Li to give Ru(CH3){(E)-CHCHC(CH3)CH2}(CO)2(PiPr3)2 (5) and with CH2CHMgBr to afford Ru(CHCH2){(E)-CHCHC(CH3)CH2}(CO)2(PiPr3)2 (6). Complex 6 is stable, and the carbon−carbon coupling between the vinyl and the α,β-unsaturated alkenyl fragment is not observed, even at high temperature (refluxing toluene). However, in the presence of 1 equiv of HBF4, complex 6 evolves to a mixture of products containing the α,β-unsaturated allyl compound [Ru{η3-CH2CHCHCHC(CH3)2}(CO)2(PiPr3)2]BF4 (7) in about 50% yield. Treatment of this mixture with an excess of NaCl gives Ru{η3-CH2CHCHCHC(CH3)2}Cl(CO)2(PiPr3) (8). Similarly, the addition of an excess of K(CH3CO2) to the mixture affords Ru{η3-CH2CHCHCHC(CH3)2}{η1-OC(O)CH3}(CO)2(PiPr3) (9). The molecular structure of 8 has been determined by X-ray diffraction analysis. The complex is pseudooctahedral with the two carbonyl groups, the chlorine atom, the phosphine ligand, and both terminal carbon atoms of the allyl unit of the α,β-unsaturated allyl ligand occupying the six coordination sites. The organic ligand has a w-shaped syn geometry. The mechanism for the carbon−carbon coupling is discussed on the basis of the reaction of 6 with DBF4, which affords [Ru{η3-CH2CHCHCHC(CH2D)CH3}(CO)2(PiPr3)2]BF4 (7-d 1).

The reactions of [Pt(NH3)2(NHCOtBu)2] and TlX3 (X = NO3-, Cl-, CF3CO2-) yielded dinuclear [{Pt(ONO2)(NH3)2(NHCOtBu)}Tl(ONO2)2(MeOH)] (2) and trinuclear complexes [{PtX(RNH2)2(NHCOtBu)2}2Tl]+ [X = NO3- (3), Cl- (5), CF3CO2- (6)], which were spectroscopically and structurally characterized. Strong Pt-Tl interaction in the complexes in solutions was indicated by both 195Pt and 205Tl NMR spectra, which exhibit very large one-bond spin-spin coupling constants between the heteronuclei (1J(PtTl)), 146.8 and 88.84 kHz for 2 and 3, respectively. Both the X-ray photoelectron spectra and the 195Pt chemical shifts reveal that the complexes have Pt centers whose oxidation states are close to that of Pt(III). Characterization of these complexes by X-ray diffraction analysis confirms that the Pt and Tl atoms are held together by very short Pt-Tl bonds and are supported by the bridging amidate ligands. The Pt-Tl bonds are shorter than 2.6 Angstrom, indicating a strong metal-metal attraction between these two metals. Compound 2 was found to activate the C-H bond of acetone to yield a platinum(IV) acetonate complex. This reactivity corresponds to the property of Pt(III) complexes. Density functional theory calculations were able to reproduce the large magnitude of the metal-metal spin-spin coupling constants. The couplings are sensitive to the computational model because of a delicate balance of metal 6s contributions in the frontier orbitals. The computational analysis reveals the role of the axial ligands in the magnitude of the coupling constants.

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