Preparation and physico-chemical studies of some chloride and alkoxide isopropoxymetallates of cobalt(II) containing {Al(OPri)4}−, {Zr2(OPri)9}− and {M(OPri)6}− Units (M = Nb or Ta)

Chloride isopropoxymetallates of cobalt(II), [ClCo{Al(OPrⁱ)₄}], [ClCo{Zr₂(OPrⁱ)₉}] and [ClCo{M(OPrⁱ)₆}] (M = Nb or Ta) have been synthesized by reactions of CoCl₂ with Li{Al(OPrⁱ)₄}, K{Zr₂(OPrⁱ)₉} and K{M(OPrⁱ)₆} in equimolar ratio. The chlorine in these chloride bimetallic isopropoxides has been replaced with alkoxide groups by their reactions with potassium alkoxides yielding products of the types, [(OR)Co{Ta(OPrⁱ)₆}] and [(OR)Co{Zr₂(OPrⁱ)₉}] (R=Me, Prⁿ, Prⁱ, Buⁿ, Bu^s or Bu^t). Alcohol interchange reactions of the above derivatives have been studied. All these new bimetallic alkoxides of cobalt(II) have been characterized by elemental analyses, IR, electronic spectral (visible) and magnetic susceptibility measurements.     

Synthesis,reactions, spectral and magnetic studies of bimetallic alkoxides of cobalt(II) with zirconium(IV)

A bimetallic isopropoxide of cobalt(II) with the formula Co[Zr₂(OPrⁱ)₉]₂, prepared by the reaction of COCl₂ with K[Zr₂(OPrⁱ)₉] in 1:2 molar ratio, has been shown to undergo alcoholysis reactions with graded alcohols (primary, secondary and tertiary) to afford products of the types, Co[Zr₂(OR)₉]₂ (where R = Me, Et, Prⁿ, Buⁿ, Buⁱ and Bu^s) Co[Zr₂(OPrⁱ)₃(OEt)₆]₂, Co[Zr₂(OPrⁱ)₆(OBu^s)₃]₂, CO[Zr₂(OPrⁱ)₃(OBu^s)₆]₂, Co[Zr₂(OPrⁱ)₆(OBu^t)₃]² and Co[Zr₂(OPrⁱ)₃(OR)₆]₂ (where R = Am^t or Bu^t). These derivatives have been characterized by elemental analyses and molecular weight determinations. Infrared, electronic (visible) spectral and magnetic susceptibility measurements suggest a distorted octahedral geometry for these derivatives.     

Crystal structures of trisammonium bisperoxotetrafluoroniobate(V) and analogous tantalate(V)

(NH₄)₃[Nb(O₂)₂F₄] (I) and (NH₄)₃[Ta(O₂)₂F₄] (II) are isostructural, and belong to the cubic Fm3m space group with four molecules in the unit cell. The unit cell parameters are a = 9.4442(4) (I) and a = 9.4512(4) Å (II). The structures were solved by the Patterson method and were refined by the least-squares method to the conventional R factors of 0.036 for 86 reflections (I) and 0.043 for 103 reflections (II) (in both structures having I ? 2σ(I)). The disordered distributions of fluorine and peroxo oxygens with partially occupied sites are observed. The disordered NH₄⁺ tetrahedra appear in the structures.The metal atoms exhibit an octahedral coordination with two corners of a polyhedron at the centre of the peroxo bonds. Inter-atomic distances are NbF, 1.95(2), NbO, 1.94, TaF, 1.91(4) and TaO, 2.07 Å.The structures (I, II) are composed of [M^υ(O₂)₂-F₄]^3? octahedra and two symmetrically-independent ammonium cations connected by NH?O and NH?F hydrogen bonds. These two structures are compared with the structure of (NH₄)₃Ti(O₂)F₅].     

Synthetic,chemical spectroscopic (infrared and electronic) and magnetic studies on dizirconiumenneaisopropoxide complexes of iron(II)

Bimetallic alkoxide derivatives of iron(II) with zirconium of the types [Fe{Zr₂(OPrⁱ)₉}₂], [ClFe- {Zr₂(OPrⁱ)₉}], [(RO)Fe{Zr₂(OPrⁱ)₉}], and [(acac)- Fe{Zr₂(OPrⁱ)₉}] have been synthesized and characterized by elemental analyses, infrared and electronic spectral as well as magnetic susceptibility studies.     

Synthesis and characterization of Cr,Mo and W carbonyl complexes of bis(2-(diphenylphosphino)ethyl)benzylamine

Various Cr, Mo and W carbonyl complexes of a tridentate ligand containing N and P as donor atoms, bis(2-(diphenylphosphino)ethyl)benzylamine (DPBA), have been synthesized. Reaction of M(CO)₆ (M = Cr, Mo and W) with DPBA in a 1:1 mole ratio in toluene or xylene, resulted in the formation of facial and meridional complexes of the type [M(CO)₃(DPBA)] (M = Cr, Mo and W). Interaction of Cr(CO)₆ or Mo(CO)₆ with DPBA and PPh₃ in toluene yielded complexes of the composition [Cr(CO)₃(DPBA)(PPh₃)] and [Mo(CO)₂(DPBA)(PPh₃)], respectively. However reaction of W(CO)₆ with DPBA and PPh₃ yielded only [W(CO)₃(DPBA)]. Reaction of Cr(CO)₆ with DPBA and 1,2-bis(diphenylphosphino)ethane(diphos) in toluene for 24 h resulted in the formation of a mixed ligand complex, [Cr(CO)₄(DPBA)(diphos)] where both the ligands coordinate to the metal atom through only one of their donor atoms. A unique binuclear complex of the composition [Mo(CO)₂(DPBA)(diphos)]₂ resulted, with the tridentate ligand DPBA acting as a bidentate bridging ligand, by the reaction of Mo(CO)₆ with DPBA and diphos in refluxing xylene for 24 h. All the complexes are characterized by elemental analysis and infrared spectra. The ³¹P{¹H} and ¹H NMR spectral data of the complexes gave valuable information in elucidating the structures of the complexes. The ligand DPBA has found to behave in a triligate monometallic, biligate monometallic, monoligate monometallic and biligate bimetallic manner.     

Structural and thermal stability studies of Ti(IV) hexanuclear oxo trimethylacetato isopropoxide complex

A new titanium hexanuclear oxo carboxylato alkoxide complex, with the general formula [Ti₆O₆(OPrⁱ)₆(OOCBu^t)₆] (1), has been synthesized in a reaction of titanium isopropoxide (Ti(OPrⁱ)₄) with Bu^tCOOH in the ratio 1:1. The structure was analyzed with the elemental analysis, IR and NMR spectroscopy, and X-ray single-crystal diffraction methods. Crystal structure of 1 was solved in the trigonal centrosymmetric system . Titanium atoms form the hexanuclear cluster, where three μ₃-oxo, two μ-carboxylato bridges and the terminal alkoxide ligand, in the distorted octahedron, surround each central cation. Analysis of spectroscopic data revealed a significant nonequivalence of interactions formed by the carboxylate groups, resulting from the asymmetry of Ti-μ-OOC bonds of carboxylate bridges in the complex molecule. TGA and MS studies suggest that volatile, titanium hexanuclear species may be formed between 423 and 553 K.     

The synthesis of technetium(V) complexes containing sterically bulky thiolate ligands. The molecular structure of tetrabutylammonium oxotetrakis(2,4,6-trimethylbenzenethiolato)technetate(V)

The reactions between [TcOCl₄]⁻ and the sterically bulky thiols ArSH (Ar = 2,4,6-Me₃C₆H₂, 2,4,6- Prⁱ₃C₆H₂ and 2,6-Ph₂C₆H₃) in methanol afford complexes of formula [TcO(SAr)₄]⁻ which may be isolated as salts with bulky organic cations. The molecular structure of [Buⁿ₄N][TcO(2,4,6-Me₃C₆H₂S)₄] was determined by X-ray diffraction methods. The Tc(V) centre was found to adopt the expected square pyramidal geometry in which an oxo group occupies the apical site and the four thiolate sulphurs the basal sites. The TcO distance is 1.659(11) Å and the average TcS distance 2.38(2) Å. The average cis STcS, trans STcS and OTcS angles are respectively 82.7(6)°, 138.4(3)° and 110.8(4)°.     

Titanium and vanadium complexes with tetraphenylimidodiphosphinate

Treatment of [Ti(OPrⁱ)₂Cl₂] with K(tpip) (tpip⁻ = [N(PPh₂O)₂]⁻) followed by chlorination with HCl afforded cis-[Ti(tpip)₂Cl]₂ (1). Reduction of 1 with Na/Hg in THF gave [Ti(tpip)₃] (2), which could also be prepared from [TiCl₃(THF)₃] and K(tpip). Recrystallization of [V(O)(tpip)₂] (3) from CH₂Cl₂-Et₂O in air afforded trinuclear [{V(O)}₃(μ-tpip)₃(μ-O)₃] (4). Treatment of [Cr(NBu^t)₂Cl₂] and [Cr(NBu^t)Cl₃(dme)] (dme = 1,2-dimethoxyethane) with [Ag(tpip)]₄ led to isolation of [Cr(tpip)₃] (6) and [Cr(NBu^t)(tpip)₂Cl] (7), respectively. The Ti- and V-tpip complexes are capable of catalyzing oxidation of sulfides with tert-butyl hydroperoxide and H₂O₂. The crystal structures of 1, 2, and 4 have been determined.     

Synthesis and characterization of some oxovanadium(V) complexes with internally functionalized oximes: Crystal and molecular structures of heptacoordinated [VO{ONC(CH3)(C4H3O-2)}3] and [VO{ONC(CH3)(C4H3S-2)}3] · 0.5C6H6

New oxovanadium(V) complexes with internally functionalized oximes of the type VO{OPrⁱ}_3−n{ONC(CH₃)(Ar)}_n] (where Ar = C₄H₃O-2, C₄H₃S-2 and C₅H₄N-2 and n = 1-3) have been prepared in quantitative yields by the reaction of VO(OPrⁱ)₃ with the corresponding oximes in various stoichiometric ratios in refluxing anhydrous benzene. The products have been characterized by elemental analyses and spectroscopic (FT IR, ¹H, ¹³C{¹H} and ⁵¹V NMR) studies. FAB mass spectral analysis of [VO{OPrⁱ}{ONC(CH₃)C₄H₃S}₂] indicates the monomeric nature of the complex. ⁵¹V NMR values for these complexes suggest the formation of tetra-coordinate species in solution. However, the single crystal X-ray diffraction studies of [VO{ONC(CH₃)(C₄H₃O-2)}₃] and [VO{ONC(CH₃)(C₄H₃S-2)}₃] · 0.5C₆H₆ exhibit the presence of vanadium(V) atoms in a unique hepta-coordination state with distorted pentagonal bipyramidal geometry in the solid state. The oxo- atom occupies the axial position while the oximato ligands are bonded in a dihapto (η²-N,O) manner with the formation of three membered rings.     

Reduction of pentaamminenitrocobalt(III) by hexaaquachromium(II) ion. Reinvestigation of the mechanism

Products of the reduction of [CoNO₂(NH₃)₅]²⁺ by Cr²⁺ were separated and identified under the conditions of [Cr²⁺]₀/[Co(IlI)]₀⩽3 and 0.02 M ⩽[H⁺] ⩽ 0.75 M. The product distribution was dependent on both [Cr²⁺]_o and [H⁺]. The following mechanism is proposed: [CoNO₂(NH₃)₅]²⁺ + Cr²⁺→Co²⁺ + [CrONO(H₂O)₅]²⁺ (i) [CrONO(H₂O)₅]²⁺ + H⁺→[Cr(H₂O)₆]³⁺ + HNO₂ (ii) [CrONO(H₂O)₅]²⁺ + Cr²⁺→Cr(IV) + [CrNO(H₂O)₅]²⁺ (iii) Cr(IV) + Cr²⁺→[(H₂O)₄Cr(OH)₂Cr(H₂O)₄]⁴⁺ (iv) HNO₂ + 2Cr²⁺→[Cr(H₂O)₆]³⁺ + [CrNO(H₂O)₅]²⁺ (v)     

Halide abstraction reactions of Sb(V) chloride: Synthesis and characterisation of hexachloroantimonate salts of M(II) M = Zn,Mg; M(III) M = Cr; and M(IV) M = Ti,Sn and related Cp2M(IV) M = Ti,Zr and Hf

Reactions of SbCl₅ with various covalent metal halides in MeCN have been studied as a convenient and direct route to metal hexachloroantimonate salts via Sb(V) halide abstraction. The isolation and characterization (Ir, Vis-UV, ¹H NMR spectroscopic and microanalytical) of the complexes [Zn(MeCN)₆][SbCl₆]₂, [CrCl₂(MeCN)₄][SbCl₆], [SnCl₃(MeCN)₃][SbCl₆], [TiCl₂(MeCN)₄][SbCl₆]₂, [Cp₂M(Cl)(MeCN)_x][SbCl₆] M = ti, x = 1; M = Zr, Hf, x = 2, and [Cp₂M(MeCN)_y][SbCl₆]₂ M = Ti, y = 2; M = Zr, Hf, y = 3, is described. The reaction of MgCl₂ with SbCl₅ was carried out in EtOAC as solvent and gave [Mg(EtOAc)₆][SbCl₆]₂. ¹²¹Sb NMR, IR and UV spectroscopic measurements provide positive identification of the SbCl_6⁻ anion.     

Cation effect on energy transfer reactions from [Tb(2,6-pyridinedicarboxylate)3] to anionic chromium(III) and neodymium(III) complexes in aqueous solutions

Cation effects are studied on the excitation energy transfer reaction between anionic complexes, i.e., [Tb(dpa)₃]³⁻ (dpa=2,6-pyridinedicarboxylate) quenched by [Cr(ox)₃]³⁻ (ox=oxalate ion), [Cr(mal)₃]³⁻ (mal=malonate ion) and [Nd(dpa)₃]³⁻ in aqueous solutions in the presence of alkali metal ions added for adjustments of ionic strengths. In the quenching reaction of [Cr(ox)₃]³⁻, magnitudes of quenching rate constants (k_q) and energy transfer rate constant in encounter complex (k₁) are changed by the cations in the order of Li⁺ < Na⁺ < K⁺ ≈ Rb⁺ ≈ Cs⁺, that is quite contrary of the cation effect on energy transfer reaction between [Ru(N-N)₃]²⁺ and [Cr(ox)₃]³⁻, reported in the previous paper. On the other hand, the rate constants in quenching reactions by [Cr(mal)₃]³⁻ and [Nd(dpa)₃]³⁻ remain almost constant. This result indicates that more separated donor-acceptor pair is not sensitive to coexisting cations.     

Copper(I)-organophosphine complexes of bis(3,5-dimethylpyrazol-1-yl)dithioacetate ligand

Copper(I) complexes have been synthesized from the reaction of CuCl, monodentate tertiary phosphines PR₃ (PR₃ = P(C₆H₅)₃; P(C₆H₅)₂(4-C₆H₄COOH); P(C₆H₅)₂(2-C₆H₄COOH); PTA, 1,3,5-triaza-7-phosphaadamantane; P(CH₂OH)₃, tris(hydroxymethyl)phosphine) and lithium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS₂]. Mono-nuclear complexes of the type [LCS₂]Cu[PR₃] have been obtained and characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H, ¹³C and ³¹P) NMR spectral data; in these complexes the ligand behaves as a κ³-N,N,S scorpionate system. One exception to this stoichiometry was observed in the complex [LCS₂]Cu[P(CH₂OH)₃]₂, where two phosphine co-ligands are coordinated to the copper(I) centre. The solid-state X-ray crystal structure of [LCS₂]Cu[P(C₆H₅)₃] has been determined. The [LCS₂]Cu[P(C₆H₅)₃] complex has a pseudo tetrahedral copper site where the bis(3,5-dimethylpyrazolyl)dithioacetate ligand acts as a κ³-N,N,S donor.     

Synthesis and reactivity of binuclear halo-bridge palladium(II) isocyanide complexes

An equimolecular mixture of [Pd(RNC)₂Cl₂] (R = Ph, p-Me C₆H₄) and [Pd(MeCN)₂Cl₂] reacts in boiling, 1,2-dichloroethane to give the binuclear complexes [Pd(RNC)Cl₂]₂.These compounds undergo a variety of bridge-splitting reactions with neutral or anionic ligands yielding complexes of the type cis and trans [Pd(RNC)LX₂] or [Pd(RNC)X₃]⁻ (L = PPh₃, pyridine, C₆H₁₁NC; X = CL, Br).By reaction of [Pd(PhNC)Cl₃]⁻ with MeOH the anionic carbene complex [Pd{C(NHPh)OMe}Cl₃]⁻ is obtained.[Pd(PhNC)Cl₂]₂ reacts with p-toluidine (excess) or o-aminopyridine to give the corresponding mononuclear carbene derivatives.In the case of the mixed derivative [Pd(p-MeC₆H₄NC)(C₆H₁₁NC)Cl₂], only the more activated p-tolylisocyanide was found to react with p-toluidine.The complexes have been characterized by elemental analysis, conductivity measurements, i.r. and ¹H n.m.r. spectra where possible.     

Computer graphics applications of electron deformation densities and electrostatic potentials in coordination chemistry

Computer programs have been developed in order to display on a raster scan device electron deformation densities and electrostatic potentials, both as 2D colour-filled contour maps and as 3D solid models. Furthermore, as this quantum chemical model has proved to be adequate for transition metal complexes, the combined use of the Xα formalism and computer graphics is expected to be of value in rationalizing the reactivity of coordination and organometallic compounds. The examples of [Cr(O₂)₄]³⁻, [Mo(O₂)₄]²⁻ and [Nb(O₂)₄]³⁻ are discussed in an attempt to understand the differences in catalytic properties exhibited by parent metal dioxygen complexes.     

A general approach to the synthesis of neutral and cationic binuclear trithiocarbonato-bridged complexes of palladium(II) or of palladium(II)—platinum(II)

Addition (1:2) of Tl₂CS₃ to solutions of perchloratocomplexes of palladium(II) Pd(OClO₃)(C₆F₅)(PR₃) leads to neutral binuclear derivatives of the type (PR₃)(C₆F₅)Pd(μ-S₂CS)Pd(C₆F₅)(PR₃)₂, whilst the reaction of perchloratocomplexes of palladium(II) or platinum(II) with the neutral Pd(η²-CS₃)(PR₃)₂ affords cationic complexes of the type [L₂Pd(μ-S₂CS)M(C₆F₅)L₂]ClO₄ (M = Pd or Pt). Spectral data (IR and ³¹P, NMR) permit the inequivocal structural characterization of both the neutral and the cationic complexes.     

Rhodium and iridium complexes bearing an alkyloxazoline-substituted indenyl ligand (Indox ligand) and their stereoselective construction of metal-centered chirality

The Indox ligands, [{(S)-(ⁱPr)Indox}_n]H (1) [n=2 (a), 3 (b)] and [{(H)Indox}_n=3]H (2), in which an indenyl group and an oxazoline ring are connected by an ethylene or propylene spacer, have been prepared. Reaction of [Ir(coe)₂Cl]₂ or [RhCl(C₂H₄)₂]₂ with the potassium salt of 1 afforded η⁵-[{(S)-(ⁱPr)Indox}_n]Ir(coe)₂ (3) or η⁵-[{(S)-(ⁱPr)Indox}_n]Rh(C₂H₄)₂ (6) as a 1:1 mixture of two diastereomers. The oxazoline ring in 3 and 6 did not coordinate to the metal center. When the complexes 3 or 6 reacted with iodine in diethyl ether, oxidative addition proceeded and the oxazoline ring coordinated to the metal center to give diiodoiridium(III) or rhodium(III) complexes, η⁵:η¹-[{(S)-(ⁱPr)Indox}_n]M(I)₂ [M=Ir (4), Rh (7)]. The corresponding diiodoiridium(III) complex bearing the Indox ligand 2, η⁵:η¹-[{(H)Indox}_n=2]Ir(I)₂ (5), was also prepared by a similar method. Reaction of 4 or 7 with PPh₃ in THF afforded diiodo-phosphine complexes, η⁵-[{(S)-(ⁱPr)Indox}_n]M(PPh₃)(I)₂ [M=Ir (8), Rh (9)] as a 1:1 mixture of two diastereomers in which the oxazoline ring dissociated from the metal center. The related reaction of 8 or 9 with more than 2 equiv. of AgOTf afforded the cationic complexes, [η⁵:η¹-[{(S)-(ⁱPr)Indox}_n]M(PPh₃)(OTf)]OTf [M=Ir (10), Rh (11)], having a stereogenic center at the metal center as a mixture of only two diastereomers. From ¹H and ³¹P NMR analyses, each diastereomer of 8 or 9 afforded only a single isomer of 10 or 11. The corresponding iridium(III) complex bearing the Indox ligand 2, [η⁵:η¹-[{(H)Indox}_n=3]Ir(PPh₃)(OTf)]OTf (12) was also prepared. The coordinated triflate ligand of 12 was slowly replaced by water in CDCl₃ to afford the dicationic aquo complex, (S^*_pl,R^*_Ir)-[η⁵:η¹-[{(H)Indox}_n=3]Ir(PPh₃)(H₂O)](OTf)₂ (13). The monocationic complex, [η⁵:η¹-[{(S)-(ⁱPr)Indox}_n=2]Ir(PPh₃)(I)]OTf (14a), having metal-centered chirality, was observed as a mixture of only two diastereomers in the reaction of 10a (a mixture of two diastereomers) with 1 equiv. of AgOTf. These observations indicated that the ligand exchange reaction of 8 or 9 with AgOTf contained the following three steps: (i) abstraction of one of the two prochiral iododes by AgOTf, (ii) recoordination of the oxazoline ring, and (iii) exchange of the remaining iodide for the triflate by AgOTf. The stereochemistry around the metal center was determined at the second step. All complexes have been characterized by usual spectroscopic methods as well as elemental analyses, and 4 and 13 have been characterized by X-ray analyses.     

Metallic perchlorate salts of N-isopropyl-and N-Cyclohexyl-2-pyrrolidinone

A series of metal perclorate complexes of N- isopropyl-2-pyrrolidinone (NIPP) and N-cyclohexyl- 2-pyrrolidinone (NCHP) have been synthesized, showing coordination through the carbonyl oxygen atom. These complexes have compositions with the general formulas [M(NIPP)_{4 or 6}]²⁺(ClO₄)₂ and [M(NCHP)₆]²⁺(ClO₄)₂ [M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)]. They have been characterized by IR spectra, electrical conductivity measurements, magnetic moments, X-ray diffraction patterns and electronic absorption spectra.     

Syntheses of 1-[2-(Phosphonomethoxy)Alkyl]Thymine Monophosphates and an Evaluation of their Inhibitory Activity Toward Human Thymidine Phosphorylase

A series of new monophosphates of 1-[2-(phosphonomethoxy)alkyl]thymines, such as PMPTp_, 3-MeO-PMPTp, HPMPTp, and FPMPTp, were synthesized and tested for their ability to inhibit human thymidine phosphorylase. Kinetic measurements of enzyme activity were performed using thymidine and inorganic phosphate as the substrates. The data show that some monophosphates provide a considerable increase of the multisubstrate inhibitory effect. The highest inhibitory potency was found with (R)-FPMPTp 4c (K _i ^dT = 4.09 ± 0.47 μM, K _i(P_i) = 2.13 ± 0.29 μM) and (R) 3-MeO-PMPTp 4d (K _i ^dT = 5.78 ± 0.71 μM, K _i(P_i) = 2.71 ± 0.37 μM).     

Secondary ion mass spectrometry of nonvolatile isocyanide complexes of silver(I) and copper(I)

A series of silver and copper coordination complexes has been studied using secondary ion mass spectrometry (SIMS). Results are presented for the monomeric silver(I) complexes [Ag(CNR)₄]X, where R = cyclohexyl for X  ClO₄⁻, and R = methyl or t-butyl for X  PF₆⁻. Likewise, Cu(I) complexes [Cu(CNR)₄]PF₆, where R =methyl, t-butyl, or cyclohexyl, were examined. The presence of AgL₂⁺ (L represents the intact RNC ligand) and the absence of AgL₃⁺ and AgL₄⁺ species attests to the gas phase stability of two-coordinate silver(I). Similar results to these were obtained for the Cu(I) complexes, with the exception of [Cu(CNCH₃)₄]PF₆ whose spectrum contains CuL₄⁺, CuL₃⁺, CuL₂⁺, CuL⁺, and Cu⁺ ions. The latter result reflects the enhanced stability of the tetrahedral Cu(I) geometry compared to Ag(I) in the gas phase. Cross labeling experiments and isotopic labeling studies have provided insights into fragmentation mechanisms. Ligand exchange occurs when mixtures are examined. These exchange reactions provide evidence for extensive molecular mixing which can accompany SIMS even under low primary ion dose conditions. Cluster ion formation as well as the observation of α-cleavage of the NC bonds of RNC ligands have been observed and these results are discussed. Granulated graphite and ammonium chloride were employed to study matrix effects. Granulated graphite enhanced NC cleavage for the silver complexes but had little effect on the relative abundance of silver cluster ions. On the other hand, copper cluster ions were more sensitive to matrix effects.