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An experiment was conducted as part of studies into the chemistry of polynuclear complexes containing anionic ligands of the N-C-X type (where X = N, O and S). The study resulted in the first tetranuclear complex with two bridging N-C-S ligands exhibiting a mu-(1:2kappaS) coordination mode. The tetranuclear complex was found to undergo a change in the mu-(1kappaN, 2kappaS) coordination mode by replacement of the ancillary ligands.

The mononuclear complex (MCl(H2Bzimt)(cod)), where M = Rh, Ir, cod = 1,5 cyclooctadiene, and Bzimt = benzimidazole-2-thiol, is a precursor for synthesizing homo- and hetero-tetranuclear complexes such as (MM'(mu-Bzimt)(cod)2)2, which have S-coordinated ligands. The dinuclear and trinuclear complexes appear as intermediates during the process. The impact of steric and anisotropic effects is reflected in the chemical shift values of olefinic protons. The 1H-NMR spectra is carried out by selective decoupling, NOE, and H,H-COSY experiments.

The preparation of new zwitterionic metalates of Cu, Ag, and Au is described. It continues the series of HRSNS complexes and show how their properties as metalloligands are extended to other metals in order to produce a series of rationally assembled multizwitterions.

Research has been conducted on the phosphine selenides. The reactivity of the tetrahedral clusters [HMCo (sub)3 (CO) (sub)12] and [Et (sub)4 N][MCo (sub)3 (CO) (sub)12], where M stands for Fe and Ru, toward these selenides has been investigated in the effort to produce chalcogenido-carbonyl bimetallic clusters and the results are reported.

The synthesis of palladium metallacycles from corresponding chloroalkylcomplexes or cyclooctadiene and bases or by ligand exchange reactions is described. The palladacycles, belonging to group 10 metallacycles, react with activated akynes and sulfur dioxide forming insertion products.

A study of a series of new Ru(II) complexes containing two chelating P,N ligands of the type (2-oxazoiln-2-ylmethyl)-diphenylphosphine (PCh2-oxazoline I), (2-oxazolin-4,4-dimethyl-2-ylmethyl)diphenylphosphine (PCH2-oxazoline-Me2 II), and (2-oxazolin-4-(S)-isopropyl-ylmethyl)diphenylphosphine (PCH2-oxazoline-Pr III is presented. The results show that four different types of octahedral coordination geometries are found with I, cis,cis,cis and trans,trans,trans geometries was characterized.

Multifunctional, hemilabile phosphine ligands are prepared using selective P-C coupling. The reaction of Li(CH2../--C(../--O)Ph) with Ph2PCl in THF affords the ketophosphine Ph2PCH2C(O)Ph in a fully chemoselective manner. This was also true for Li(CH2../--C(../--O)NPh2), which leads to Ph2PCH2C(O)NPh2. The reactivity of the phosphino enolates of mononuclear palladium and platinum and dinuclear copper complexes toward coordinated nitrile ligands and organic isocyanates is also described.

Platinum complexes with phenanthroline (phen) substituents in the ortho position undergo rotation of the ligand plane with respect to the N-Pt-N' plane. This is accompanied by displacement of the equatorial iodine atoms from the coordination plane and ligand distortion. Rotation of the ligand plane is less in octahedral (PtI4(2.9-Me2-4,7-Ph2phen)).I2 than in square planar PtI2(2.9-Me2-4,7-Ph2phen). For Pt(II) complexes with planar geometry, reduction process involves one-electron species. Distorted Pt(II) complexes undergo irreversible reduction via simplification of the complex geometry.

The structures of two isolated isomers of the phosphido-bridged platinum cluster Pt3(mu-PPH2)3Ph(PPh3)2 showed nearly equilateral 42-electron clusters and varying Pt-Pt distances determined by the number of electrons contributed by the different bridging ligands. Both clusters exhibited the first example of reversible core isomerism brought about by the presence or absence of the Pt-Pt bond. Interconversion of the two isomers can reportedly be done by replacing the crystallization solvent. The distortion of the Pt3 core due to the substition of a phosphine ligand with a better omega-donor ligand resulted to the formation of the two isomers.

NMR spectroscopic analysis enables the analysis of exchange of donor nitrogen and rotations near the Pt-P and P-C bonds of the phosphine in platinum (II) complexes having monocoordinated 2,9-dimethyl-1, 10-phenanthroline (Me2-phen) and phosphine ligands. Nature of the trans ligand influences the measured free energy values for bidentate ligand flipping with converging lone pairs of electrons. X-ray study suggests a stacking interaction of a phenyl ring of PPh3 with Me2-phen aromatic system, leading to high rotation barrier for phosphine group.

Cobalt(II) complex is synthesized and its reaction with ketophosphine ligand Ph2PCH2C(O)Ph is studied. An analysis of Co(II)-ketophosphine complexes CoX2(Ph2PCH2C(O)Ph)2, where X is a halogen, reveals their state of tetrahedral-octahedral equilibrium in methanol. The reactions of CoCl2(Ph2PCH2C(O)Ph)2 with AgBF4, TlPF6 and Na(Co(CO)4) are studied.

Investigations were conducted to synthesize cobalt (II) complexes (CoX2(Ph2PCH2C(O)R)2) consisting of keto phosphine ligands. Single-crystal X-ray studies were used to establish the solid state structure of the fac and mer isomers.

Cyanide-substituted anionic complexes such as Na(Cp'Mn-(CO)2CN), where Cp' is eta-MeC5H4, never have a metal-centered HOMO, unlike many other carbonylmetalates of the transition metals. These complexes possess nitrogen-based orbitals which prefer coordination to metal centers by a cyanide moiety, resulting in the generation of the Mn-CN-M' chain systems. The coordination through the CN in the terminal and bridging modes is effected by the cyanometalate ligand (Cp' Mn(CO)2CN)-.

Heterometallic carbonyl complexes were prepared by reaction of dppm (dppm = Ph2PCH2PPh2) with linear trinuclear chain complexes trans-Pt or Pd (m(CO))2(NCPh)2 m(CO) = Mo(CO)3Cp, W(CO)3Cp, Mn(CO)5, Co(CO)4. The products have different structures depending on the nature of the metal carbonyl fragment M(CO). The crystal structure of (eta2-dppm)Pt(micro-dppm)W(CO)2Cp (PF6) and reactivity studies leading to the synthesis of heterobimetallic hydrido complexes were also reported.

The binuclear complexes Rh2(mu-L)(diolefin)2 L = CA2-, DHBQ2-; diolefin = cycloocta-1,5-diene (cod), norborna-1,5-diene, tetrafluoro- (5,6)bicyclo(2.2.2)octa-2,5,7-triene were synthesized from the reaction of Rh2(mu-OMe)2(diolefin)2 with chloranilic acid (H2CA) or 2,5-dihydroxy-1,4-benzoquinone (H2DHBQ). The complex Rh4(mu-CA)2(cod)4 was also obtained and upon dissolution in a solvent and crystallization gave Rh2(mu-CA)(cod)2. The complexes were characterized by X-ray diffraction techniques.

The reaction of (Rh(COD)(mu-Cl))2 (COD = cycloocta-1,5-diene) and the monodentate P-bonded ligand 2-(diphenylphosphino)-6-methoxypyridine (Ph2PPyOMe) in benzene solution produced (Rh(COD)(Ph2PPyOMe)Cl). Displacement of the COD ligand led to the formation of cis-(Rh(CO)2(Ph2PPyOMe)Cl) from which additional Ph2PPyOMe gives trans-(Rh(CO)(Ph2PPyOMe)2Cl). Further reactions with copper and gold complexes and product characterization were reported.

Methanolic dirhodium tetraacetate reacts with triphenylphosphine to yield the reactive Rh2(OAc)3(C6H4PPh2)(AcOH) which, on heating with excess PPh3, forms Rh2(OAc)2(C6H4PPh2)2(PPh3)2 and Rh2(OAc)2(C6H4PPh2)2(PPh3)(AcOH). These two doubly metalated complexes have respective head-to-tail and head-to-head structures. The product mix may also be obtained in one step by the use of excess PPh3 in refluxing acetic acid or of chloro- or p-methylarylphosphine. The proposed reaction mechanisms involve axial coordination of one PPh3 to two Rh atoms, rearrangement to equatorial coordination by displacement of an OAc group and protonation of the OAc from the phosphino phenyl ring.

Electrophiles react with heterometallic complexes either by terminal addition to a metal center or by bridging the metal-metal bond. The reactions of three phosphido-bridged m(mu-PPh2)Pt(PPh3)2 complexes with etheric HBF4 in CH2Cl2 to yield hydrido-bridged m(mu-PPh2)(mu-H)Pt(PPh3)2-(BF4) complexes involve metal-to-metal bridging. The reaction of m(mu-PCy2)Pd(PCy2H)2 with HCl to yield m(mu-PCy2)(mu-H)Pd(PCy2H)Cl involves 1,2 mutual exchange between Cl and PCy2H as well. The substitution follows protonation and happens only with cationic compounds. Related reactions together with structural details of a heterotrimetallic tetranuclear W2AuPt complex are discussed.

The complex trans-Pd(m)2(CO)2(NCPh)2 reacts with PR2H (R = Ph, Cy) to yield six dinuclear m(mu-PR2)Pd(PR2H)2 complexes, while trans-Pt(m)2(CO)2(NCPh)2 reacts with PCy2H to yield the m(mu-PCy2)Pt(CO)(PCy2H) forms, where 'm' is Cr(CO)2Cp, Mo(CO)2Cp, W(CO)2Cp or Mn(CO)4. The second reaction involves an R2P-m(CO) reaction with a Pt(0) complex where the terminal phosphine farther away from the PR2 bridge is replaced by an incoming CO. When the ethylenes of Pt(C2H4)2(PPh3) are replaced by Ph2P-Mn(CO)4 fragments, a new complex (CO)4(mu-PPh2)Mn-Pt(PPh3)-Mn(mu-PPh2)(CO)4 is formed. Its structure and spectral characteristics are presented.

The Fe-Au complex (AuFe Si OMe 3 CO 3 mu-dppm)2, where dppm = Ph2PCH2PPh2, was unexpectedly produced from the reaction of (Bu4N)(AuX2), where X = Cl and Br, with K(Fe Si OMe 3 CO 3 dppm-P). The dimeric complex has an approximate C2 symmetry and the Fe-Au-Au-Fe chain possesses a Z shape. On the other hand, the reaction of K(Fe Si OMe 3 CO 3 dppm-P) with the intermediate Fe(Si OMe 3)(CO)3(mu-dppm)HgCl yielded the chain complex Hg(Fe Si OMe 3 CO 3 dppm-P)2. The chain complex has an approximate C2 symmetry with a linear Fe-Hg-Fe array.

The synthesis and structural characterization of the trans-diaquabis(amidato) complex of platinum(II) are described. X-ray crystal structure analysis showed the coordination of two amidato ligands and two water molecules to platinum. The water oxygen was shown to exert a smaller ground state trans-influence than the amine nitrogen. The inplane orientation of the amidato ligand is attributed to the strong H bonds which link the cis amidato and water ligands.

The catalytic hydrogenation of acetophenone by new phosphine-free ruthenium-diamine complexes which showed rare N-dealkylation of the diamine is reported.

Reactivity of Ph2P(Se)CH(sub 2)C(sub 6)H(sub 4)CH(sub 2)P(Se)Ph2 with [M3(CO)(sub 12)] (M=Ru or Fe). Synthesis and characterization of the new carbene cluster [Ru3(mu3-Se)(mu2-PPh2)(CO)(sub 6)(mu2-CHC6H4CH2PPh2)]

Experimental evidence shows that the 33-electron binuclear radical (Mo(sub 2)(eta(super 5)-C(sub 5)H(sub 5))(sub 2)(mu-PPh(sub 2))(CO)(sub 4)) exhibits a wide range of chemical reactions. The chemistry of the radical includes several processes that are similar to those of mononuclear organometallic radicals such as ligand displacement, atom transfer and metal-metal bond formation. Carbonyl displacement and atom-transfer processes take place in the reactions of the binuclear radical with secondary phosphines or thiols.