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A linear tetraphosphine meso-bis[(diphenylphosphinomethyl)phenylphosphino]methane (meso-dpmppm), was utilized to prepare a PtI dinuclear complex, [Pt2(μ−meso-dpmppm−κ2,κ1)(XylNC)3](PF6)2 (2), which was derived from reaction of [PtII(meso-dpmppm−κ3)(XylNC)](PF6)2 (1) with 1/3 equiv. of [Pt3(XylNC)6]. Treatment of 2 with 1/3 equiv. of [Pt3(XylNC)6] gave an A-frame Pt3 complex, [Pt3(μ−meso-dpmppm−κ2,κ1)(XylNC)5](PF6)2 (3), demonstrating that a meso-dpmppm ligand effectively support the expansion of platinum nuclearity from Pt2+ through {Pt2}2+ to {Pt3}2+ cores in stepwise fashion. Reaction of 2 with 1 equiv. of meso-dpmppm afforded [Pt2(μ−meso-dpmppm−κ2,κ1)2](PF6)2 (4), which would not react with [Pt3(XylNC)6], and in contrast, treatment of 3 with excess of [Pt3(XylNC)6] gave birth to a decanuclear platinum complex, [Pt10(μ−meso-dpmppm−κ2,κ1,κ1)2(XylNC)18](PF6)6, (5), comprised of a linear Pt4 chain {Pt4(XylNC)8}2+ terminated by two Pt3 A-frame units of {Pt3(μ−meso-dpmppm−κ2,κ1,κ1)(XylNC)5}2+, which is an interesting nano-ordered Pt cluster constructed with small size multinuclear building blocks, and notably contains the longest metal–metal bonded Pt chain without any bridging ligands.

Reactions of the dinuclear palladium(I) complex, [Pd 2 (RNC) 6 ](PF 6 ) 2 (R=2,6-xylyl (Xyl), 2,4,6-mesityl (Mes)), with 1,1′-bis(diphenylphosphino)ferrocene (dppf) gave dipalladium(I) complexes with dppf ligands, [Pd 2 (dppf) 2 (RNC) 2 ](PF 6 ) 2 ( 1 , R=Xyl, 66%; 2 , R=Mes, 18%), which were characterized by elemental analysis, 1 H- and 31 P-NMR spectroscopy, IR and UV–vis absorption spectroscopic analyses, and cyclic voltammetry. The structure of 1 was characterized by X-ray crystallography. The cation of compound 1 is composed of two Pd(I) atoms joined by a PdPd σ-bond (2.602(1) A), and each palladium ion has a square planar structure ligated by a terminal isocyanide, two P atoms of dppf, and the neighboring Pd atom. The dppf ligands chelate to the metal with an average PPdP bite angle of 99.19° and an average Pd⋯Fe distance of 4.236 A. The cyclopentadienyl rings of dppf ligands are in staggered form. The 1 H- and 31 P-NMR and the electronic absorption spectra of 1 and 2 indicated that the metalmetal bonded structure as observed in the crystal of 1 was retained in the solution. Complexes 1 and 2 were extremely photosensitive, and underwent a homolytic cleavage even under a room light. The reaction was monitored by the electronic absorption spectral changes and might generate a cation radical, [Pd(dppf)(RNC)] + . The cyclic voltammograms of 1 and 2 in acetonitrile solution showed two successive quasi -reversible oxidation waves at E 1/2 =0.60, 0.72 V (vs. Ag/AgPF 6 ) ( 1 ) and 0.62, 0.73 V ( 2 ) and an irreversible reduction wave at E 1/2 =−1.23 V ( 1 ) and −1.22 V ( 2 ). The former oxidation waves can be assigned to Fe(II)/Fe(III) processes of the two ferrocenyl groups and demonstrated that a charge-transfer communication between the Fe centers occurred through the PdPd single bond.

Reaction of [(η6-C6Me6)RuCl(MDMPP-P,O)] 1 (MDMPP-P,OP(2-O-6-MeOC6H3)Ph2] with CO under high pressure at 95° gave RuCl(CO)3(MDMPP-P,O) 2. [(η6-p-cymene)Ru(TDMPP-P,O,O)] (TDMPP-P,O,OP(2-O-6-MeOC6H3)2{2,6-(MeO)2C6H3}) reacted with CO or CO/2,6-xylyl isocyanide under high pressure to form Ru(CO)3(TDMPP-P,O,O) 4 or Ru(CO)2(XyINC)(TDMPP-P,O,O) 5 (Xyl=2,6-Me2C6H3), respectively. Reactions of 1 with Lewis bases in the presence of NH4PF6 gave [(η6-C6Me6)RuL(MDMPP-P,O)](PF6) 6 (L=CO, XylNC). Complex 1 reacted with mono-substituted acetylenes in acetone in the presence of bases to form the metal alkynyl complexes [(η6-C6Me6)Ru(CCR)(MDMPP-P,O)] 7. Similar reaction of 1 with PhCCH in the presence of NaPF6 in acetone or MeOH gave a vinylidene 8a (R=CCHPh) and a carbene complex 9a (R=CCH2Ph(OMe)) [(η6-C6Me6)Ru(R)(MDMPP-P,O)](PF6), respectively. A reaction of 1 with HCCCMe2OH and NaPF6 in MeOH gave a metallabutadiene complex 10c [(η6-C6Me6) Ru{C(OMe)CHCMe2}(MDMPP-P,O)]. X-ray analyses of 6b (L=XylNC), 7a (R=Ph) and 7e (R=CH2OH) were carried out to confirm the structures; 6b, monoclinic, space group P21/c (No. 14), a=9.910(8) A, b=25.370(7) A, c=16.020(7) A, β=105.29(5)°,V=3885(7) A3, Z=4, R=0.050, Rw=0.053 for 4064 reflections (I>3.0σ(I)); 7a, orthorhombic, space group Pbca, a=17.222(4) A, b=23.772(8) A, c=16.003(8) A, V=6552(7) A3, Z=8, R=0.052, Rw=0.052 for 1836 reflections (I>3.0σ(I)); 7e, triclinic, space group P1 (No. 2), a=10.639(4) A, b=14.778(3) A, c=10.214(3) A, α=97.05(2)°, β=113.01(2)°, γ=79.12(2)°, V=1449(2) A3, Z=2, R=0.041, Rw=0.040 for 3270 reflections (I>3.0σ(I)).

Reaction of [Pd2(RNC)6](PF6)2 with dpmp (2 equiv.) generated dipalladium complexes, [Pd2(dpmp)2(RNC)2](PF6)2 (1), in good yields, where R = 2,6-xylyl (Xyl) and 2,4,6-mesityl (Mes), Complex 1a (R = Xyl) was characterized by X-ray crystallography to have a metal-metal bonded dinuclear structure (Pd−Pd = 2.607(2) A) without bridging ligand. The dpmp ligand chelates to the metal through only the terminal phosphorus atoms. Complex 1a in acetonitrile easily lost one isocyanide ligand and was transformed into a dpmp-bridged dipalladium complex, anti-[Pd2(μ-dpmp)2(XylNC)] (PF6)2 · CH3CN ((2a)CH3CN). The dinuclear core of 2a consists of a three- and a four-coordinate Pd atom bridged by two dpmp ligands (Pd−Pd = 2.702(1) A). Complex la was restored by treatment of 2a with an excess of XylNC. When compound 1 was treated with zero-valent palladium complex [Pd3(RNC)6], A-frame trinuclear complex, A-frame-[Pd3(μ-dpmp)2(RNC)2](PF6)2 (4), was obtained. The trimer 4 was also prepared by the reaction of [Pd3(RNC)8](PF6)2 with dpmp (2 equiv.) via a linear dpmp-bridged trimer, linear-[Pd3(μ-dpmp)2(RNC)2](PF6)2 (3). Complex 4a (R = Xyl) was analyzed by X-ray crystallography to be a trinuclear A-frame structure joined by two Pd−Pd σ-bonds (Pd−Pd = 2.592(2) A, Pd−Pd−Pd = 79.19(8)°). The two dpmp ligands doubly bridge between the three metal atoms. Whereas, complex 4 was thermally and chemically stable, complex 3a (R = Xyl) reacted with I2 to lead to a trinuclear Pd(II) complex, [{PdI2(dpmp)2)2PdI2] (5), which was characterized by an X-ray analysis. The two cis-PdI2(dpmp) units were joined by trans-PdI2 fragment without metal-metal bonds.

Reaction of xylyl isocyanide with chloroacetone in the presence of [Co2(XylNC)8] (Xyl = 2,6-Me2C6H3) gave the derivatives of azacyclopent-3-ene (CH3COCH3)(XylNC)4 1 and cobaltaazacyclobutane CoCl(CH3COCH)(XylNC)5 2. Similar reaction with methyl monochloroacetate gave the analog of 1 (CH3COOMe)(XylNC)4 4 and the 2,6-diaza-bicyclo[3,3,0]octa-1,7-diene derivative (CHCOOMe)(XylNC)5 · C6H6 5 ·C6H6. Compounds 1 and 5·C6H6 were confirmed by their X-ray analyses (1 monoclinic, space group Cc (No. 9), a = 10.241(3), b = 19.474(6), c = 16.955(8) A , β = 03.42(3)°, V = 3289(2) A 3 , Z = 4, and R = 0.043 ; 5 ·C6H6 orthorhombic, space group Pbcn (No. 60), a = 21.642(5), b = 14.028(3), c = 30.449(8) A , V = 9244(7) A 3 , Z = 8 , and R = 0.087). A possible reaction route is discussed.

Reaction of [Pd2(RNC)6]2+ with (Ph2PCH2)2PPh (dpmp) [Pd2(dpmp)2(RNC)2]2+ 1, in which dpmp ligands acted as chelating ligands. Thermal reaction of 1 underwent an elimination of isocyanide and change of a coordination mode of the dpmp ligands to give [Pd2(dpmp)2(RNC)]2+ 2. Two kinds of new dimeric complexes [Pt2(dpmp)2(RNC)2]2+ (4,5) were obtained from [Pt2(RNC)6]2+ and dpmp, in which dpmp ligands acted as bi- and tridenate ligand to bridge a metal-metal bond. Compounds 4 and 5 are interconvertible. Reaction of 5 with M3(RNC)6 (M = Pt, Pd) gave a linear homo- or hetero trinuclear complex, [Pt2M(dpmp)2(RNC)2]2+ (6, 7).

Reactions of diruthenium alkyl-halido complexes containing two bridging thiolate ligands [ Cp ∗ RuR (μ- SPr i ) 2 RuCp ∗ X ] ( 1 ; Cp ∗ = ν 5 C 5 Me 5 , R = PhCH 2 CH 2 , X = Br, R = Me, X = I with R′MgX (R′ = PhCH2CH2, X = Br; R′ = PhCH2, X = Cl) or R′Li(R′ = Me, PhC≡C in THF at room temperature afforded novel diruthenium alkyl-alkyl and alkyl-alkynul complexes [Cp∗RuR(μ-SPri)2RuCp∗R′] (2). In contrast, treatment of 1a (R = PhCH2CH2, X = Br) with EtMgBr resulted in the formation of an alkyl-hydrido complex [Cp∗Ru(CH2CH2Ph)(μ-SPri)2RuCp∗H] as the only isolable product. X-ray analysis of 2a (R = R′ = PhCH2CH2) has disclosed the structure as consisting of the two Cp∗Ru(CH2CH2Ph) units connected by two μ-SPri ligands together with a RuRu single bond, in which the two alkyl groups are oriented mutually cis. Crystal data for 2a: monoclinic, space group P21/c (No. 14) with a = 19.449(3) A , b = 10.210(3) A , c = 20.254(2) A , β = 94.684(9)°, V = 4008(2) A 3 , Z = 4 , and R(Rw = 0.054 (0.041) for 2635 reflections [I > 3 σ (I)]. Treatment of 2a with two equivalents of I2 in THF resulted in the formation of PhCH2CH2I and [Cp∗RuI(μ-SPri)2RuCp∗I] (7c) as the major products, while treatment with 1.2 equivalents of I2 afforded a mixture of Ph(CH2)4 Ph and PhCH2CH2I along with 7c and unidentified Ru species.

Treatment of the dinuclear molybdenum complex [Mo2(O2CCH3)2(CH3CN)6](BF4)2 with aromatic isocyanides (RNC) gave an oxo-bridged dinuclear molybdenum(II) complex, [Mo2(μ-O)(RNC)10](BF4)2 (1), and a mononuclear molybdenum(IV) complex, [Mo(= O)F(RNC)4]BF4(2) (R = 2,6-dimethylphenyl (Xyl) or 2,4,6-trimethylphenyl (Mes)), which were characterized by IR, electronic, 1H and 19F NMR spectroscopy and X-ray crystallographic analyses. Complex 1a (R = Xyl) crystallizes in the triclinic form, space group P 1 , with a = 13.431(5) A , b = 15.548(7) A , c = 12.616(5) A , α = 111.74(3)°, β = 92.80(3)°, γ = 101.80(3)° and Z = 1 (R = 0.060 and Rw = 0.054 for 2818 independent reflections with I >3σ(I)) Complex 2b (R = Mes) crystallizes in the triclinic form, space group P 1 , with a = 14.317(4) A , b = 16.16(1) A , c = 8.968(8) A , α = 100.31(4)°, β = 97.54(2)°, γ = 91.69(4)° and Z = 2 (R = 0.059 and Rw = 0.059 for 2225 independent reflections with I >3σ(l)) Complex 1 consists of two molybdenum atoms bridged linearly by an oxygen atom. Each molybdenum atom is octahedrally coordinated by five isocyanides and an oxygen atom. Two equatorial planes, Mo(RNC)4, mutually adopt an eclipsed form. The MoO bond length is 1.876(2) A and the MoOMo angle is constrained to 180°. Complex 2 has a distorted octahedral geometry, in which molybdenum atom is occupied by four isocyanides, O and F atoms.

The reaction of Co 2 (XylNC) 8 (Xyl = 2,6-Me 2 C 6 H 3 ) with 2-bromoacetophenone gave 2,3-bis(2,6-xylyl)imino-5-phenyl-2,3-dihydrofuran ( 1a ) and the cobalta-azacyclopentane derivative CoBr(PhCOCH)(XylNC) 6 ( 2a ). Structures of 1a and 2a were determined by X-ray analyses; 1a is a furan derivative and 2a has a distorted octahedral structure containing a five-membered metallacyclic moiety formed by an multiple insertion of isocyanide into a CoC bond. Similar treatment at reflux in the presence of xylyl isocyanide gave two kinds of octahedral compounds, 3a and 4a , having similar formula composition CoBr(PhCOCH)-(XylNC) 5 ; 3a was found by X-ray analysis to have a cobaltacycle structure, containing a tridentate ligand consisting of sigma carbon, carbene and O-coordination sites, and 4a was proposed to have a cobalta-azacyclobutane framework.

(η5-In)Ru(η1-C-)(PPh3)2 (In = indenyl) treated with nitric oxide (1 atm) in the presence of NaClO4 gave [(η5In)Ru(CO)(PPh3)2]ClO4·0.5CH2Cl2 and benzonitrile (PhC-N) in good yields, through a novel metathesis reaction between σ-acetylide and NO.(η6-C6Me6)Ru(η1-C-CPh)(PPh3)Cl also readily underwent the metathesis reaction with NO to afford benzonitrile.

Reaction of trans -Pd(PPh 3 ) 2 I(CH 3 ) ( 1a ) with 2,6-xylyl isocyanide in a 1:1 molar ratio led to a spontaneous insertion of isocyanides into a PdC bond to give the tris-imino insertion product 2a . The structure was determined by an X-ray analysis. The crystals are triclinic with space group P 1 ( a = 14.638(9), b = 15.662(7), c = 7.895(3) A, α = 85.06(6), β = 82.84(4), γ = 102.4(4)°, and Z = 2; R = 0.066 for 2076 independent reflections with F 0 > 5σ( F 0 ). The tris-imino group acts as a bidentate ligand through C- and N-coordinations. The 2-methyl-1-naphthyl complex, trans -Pd(PPh 3 )Br(2-CH 3 C 10 H 9 ) reacted with 2,6-xylyl isocyanide to give a bis-imino complex containing μ 2 -Br bridging ligands. Using p -nitirophenyl isocyanide, the reaction produced a mono-imino compound. Reaction of 2a with CuCl 2 gave a mixed metal complex, in which the copper(II) atom is coordinated to two neighbouring imino-nitrogens.

The reaction of bis(2-bromoethyl)selenium dibromide (1a) with 1,5-hexadiene (2) in methanol or ethanol affords 2,5-bis(alkoxymethyl)tetrahydroselenophene-1,1-dibromides (R  CH3 (3b), R  C2H5 (3c)) via 2,5-bis(bromomethyl)tetrahydroselenophene-1,1-dibromide (3a). The reaction of 1a with 2 in 1-propanol, 2-methyl-1-propanol or 1-butanol in the presence of sodium carbonate gave 2,5-bis(alkoxymethyl)tetrahydroselenophene (R  C3H7 (4a), R  (CH3)2CHCH2 (4b) and R  C4H9 (4c)) via 3a. The ratios of the trans and cis isomers of 3a–3c are 3:2. In addition, the structure of trans-2,5-bis(methoxymethyl)tetrahydroselenophene-1,1-dibromide (trans-3b) was determined by X-ray crystallography.

When Pt(COD)Cl 2 was treated with sodium amalgam in the presence of aromatic isocyanide (RNC, R = 2,6-Me 2 C 6 H 3 (Xyl) or 2,4,6-Me 3 C 6 H 2 (Mes)) and diphosphine with long methylene chain (diphos = Ph 2 P(CH 2 ) n PPh 2 , n = 5 (dpppn) or 6 (dpphex)), two kinds of Hg-Pt mixed metal clusters, [Hg 2 Pt 6 -(diphos) 2 (RNC) 8 ] ( 2 ) and [Hg 2 Pt 6 (diphos) 3 (RNC) 6 ] ( 3 ), were obtained. The structure of 3b (R  Xyl, diphos  dpphex) was determined by an X-ray analysis to be a cage-type cluster where a HG 2 unit was incorporated into a trigonal-anti-prismatic platinum core, two Pt 3 triangles being supported by three dpphex ligands (close-type). The cluster 2 was assumed to have an incomplete cage-type structure (open-type), and was converted to close-type 3 by treatment with an equivalent diphosphine ligand. When dppb ( n = 4) was used, an open-type mixed metal cluster in which one mercury atom was captured, [HgPt 6 (dppb) 2 (RNC) 8 ] ( 4 ), was obtained as the sole product.

The reaction of PdCl2(RNC)2 (RNC = isocyanide) with indenyl lithium (InLi) gave a binuclear palladium complex, [Pd2(μ-η3-In)2(RNC)2], in which the Pd2(RNC)2 unit is sandwiched between two μ-η3-indenyl groups in a syn arrangement.

Treatment of trans-[W(N2)2(dppe)2] (dppe = Ph2PCH2CH2PPh2) with N,N-dimethylformamide (DMF) in benzene under reflux afforded trans-[W(CO)(DMF)(dppe)2], together with a hydridocarbamoyl complex [WH(η2-CONMe2)(dppe)2] as the intermediate stage of this decarbonylation reaction. The detailed structure of the latter complex was determined by X-ray crystallogrpahy. Reaction of trans-[W(CO)(DMF)(dppe)2] with N2 afforded trans-[W(CO)(N2(dppe)2], whose solution in benzene was further converted into a coordinatively unsaturated complex [W(CO)(dppe)2] under reflux in an Ar atmosphere. Subsequent treatment of [W(CO)(dppe)2] with H2 gas gave a dihydrido complex [WH2(CO)(dppe)2].

Electrochemical oxidations of trans-RuCl2(RNC)4 (1) and trans,trans,trans-RuCl2(RNC)2(PPh3)2 (2) (R = t-Bu, 2,6-Me2C6H3, 2,4,6-Me3C6H2, 4-Br-2,6-Me2C6H2, or 2,4-t-Bu2-6-MeC6H2) are quasi-reversible. Half-wave potentials of 1, which are higher than those of 2, are increased by the electron-withdrawing ability of isocyanide ligands. Macroscopic electrolysis of 1 and 2 in a MeCNNaClO4 solution gives a reddish violet and a blue complex, [RuCl2(RNC)4](ClO4) (3) and [RuCl2(RNC)2(PPh3)2](ClO4) (4), respectively. An X-ray diffraction study of 3c (R = 2,4,6-Me3C6H2) shows that the stereochemistry of the starting compound 1c is retained.