The steric effect of o-tolyl ligand on the fluxionality behavior of some binuclear organoplatinum(II) complexes with bis(diphenylphosphino)methane as bridging ligand

A series of binuclear organoplatinum(II) complexes of general formula cis,cis-[R₂Pt(μ-SMe₂)(μ-dppm)Pt(o-MeC₆H₄)₂], 3a-3d, in which R = Ph, p-MeC₆H₄, m-MeC₆H₄ or p-MeOC₆H₄, were prepared by the reaction of monomeric precursors [Pt(o-MeC₆H₄)₂(dppm)] and cis-[PtR₂(SMe₂)₂]. The binuclear dialkyl analogs, in which R = Me (3e) or R₂ = {(CH₂)₄} (3f), were prepared by the reaction of cis-[Pt(o-MeC₆H₄)₂ (SMe₂)₂] and [PtR₂ (dppm)]. The complexes were fully characterized by multinuclear (¹H, ¹³C, ³¹P, ¹⁹⁵Pt) NMR spectroscopy each as a mixture of syn and anti isomers (depending on the relative orientations of Me substituents on o-tolyl ligands) and each isomer was shown to have a rigid structure. Other binuclear analogs , 3g-3j, in which R is a less steric demanding aryl groups m-MeC₆H₄ or p-MeOC₆H₄, and R′ = Me or , were prepared by the reaction of cis-[PtR₂(SMe₂)₂] and , and shown to have fluxional structures.     

Palladium(II) iminophosphine complexes

New complexes of general formula [PdCl₂(NP)] (NP = o-Ph₂PC₆H₄-CH=N-R; R = Me, ⁱ Pr, ^t Bu, NH-Me) and [Pd(NP)₂](ClO₄)₂ (NP = o-Ph₂PC₆H₄-CH=N-R; R = Me, ⁱ Pr) have been prepared by directly reacting the precursor PdCl₂(PhCN)₂ with iminophosphines (NP) in 1:1 and 1:2 molar ratios respectively. When the chloro-complex [PdCl₂(o-Ph₂PC₆H₄-CH=N ⁱ -Pr)] was treated with CF₃SO₃Ag in MeCN, the labile complex [Pd(o-Ph₂PC₆H₄-CH=N ⁱ -Pr)(MeCN)₂](CF₃SO₃)₂ was obtained in good yield. The reactivity of the new precursor towards a variety of neutral N- and P-donor ligands (py, PMe₂Ph, PMePh₂, PEt₃, bipy, dppe, 2-thpy) has been studied. The new complexes were characterized by partial elemental analyses and by spectroscopy (i.r., ¹H- and ³¹P-n.m.r.). The molecular structure of the aquo-complex [Pd(NP)(2-thpy)(H₂O)](CF₃SO₃)₂ has been determined by a single-crystal diffraction study, showing that the iminophosphine acts as a chelating ligand with coordination around the palladium atom slightly distorted from square-planar geometry.     

Synthesis and spectroscopic studies of substituted molybdenum carbonyls ofN,N′-ethylenebis(1,2-dimethylpyrazole-3-carboxaldeneimine) and monodentate tertiary phosphines

Summary Improved preparations ofcis-[LMo(CO)₄],cis-[L₂Mo(CO)₂], and [LMo(CO)₃P] where L=N, N-ethylenebis(1, 2-dimethylpyrazole-3-carboxaldeneimine) and P=P(p-MeOC₆H₄)₃, P(p-MeC₆H₄)₃, P(p-ClC₆H₄)₃ or P(o-MeC₆H₄)₃ are reported. The compounds were characterized by elemental analysis and i.r., electronic and³¹P n.m.r. spectra. The (CO) values for the nonphosphine complexes indicate Mo(4d)–L(^*) back-bonding. Furthermore, L exists in two different configurations in the [{LMo(CO)₄}₂] and the monomeric derivatives. Electronic spectral data are discussed in terms of the effect of the -acceptor tendency of the Mo(4d)–L(^*) back bonding.³¹P n.m.r. and i.r. data of the phosphine-containing compounds indicate that the more electron-withdrawing substituents on the phosphines gave larger³¹P coordination chemical shifts and larger CO frequencies.     

Syntheses,crystal structures and biological activity of the dialkytin complexes based on 2-oxo-3-phenylpropionic acid salicyloylhydrazone

Three new dialkytin complexes, {[o-OH–C₆H₄(O)C=N–N=C(CH₂Ph)COO](n-Bu₂Sn)}_n (1), {[o-OH–C₆H₄(O)C=N–N=C(CH₂Ph)COO](MeOH)(p-MeC₆H₅CH₂)₂Sn}₂ (2), and {[o-OH–C₆H₄(O)C=N–N=C(CH₂Ph)COO](EtOH)(C₆H₅CH₂)₂Sn}₂ (3), were synthesized by reactions of 2-oxo-3-phenylpropionic acid salicyloylhydrazone with the corresponding diorganotin(IV) complex, respectively. All the complexes were characterized by IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectra, elemental analysis, X-ray single crystal diffraction and TGA. For in vitro antitumor activities, complexes were evaluated by the MTT assay against three human cancer cell lines (NCI-H460, HepG2 and MCF7) and human cell line (HL7702). The results showed that 1 may be a better potential candidate for further chemical optimization and cancer therapy than 2 and 3. The interactions between the complexes and calf thymus DNA were studied; the interaction of 1 with calf thymus DNA was intercalation, 2 and 3 were intercalation and electrostatic binding.     

Preparation,characterization and Mössbauer spectra of the iron(III) complexes of some dihydroxamic acids and amino monohydroxamic acids

Summary Fe^III complexes have been prepared from the dihydroxamic acids (CH₂)_n[CON(R)OH]₂ (n=2, 3, 4, 6, 8; R=H, Ph,o-tolyl,p-tolyl) (H₂L) and the amino monohydroxamic acids H₂NCH(R)CONHOH (R=H, Me) (HL) and XC₆H₄CONHOH (X=o-NH₂,p-NH₂) (HL). Based on elemental analyses, molecular weight data, and electronic and i.r. spectra, the complexes have been formulated as Fe₂(LH)₂L₂, Fe₂L₂O and Fe₂L₃ for the dihydroxamic acids, and Fe(OH)₄L₂(H₂O)₂ and FeL₃ for the amino monohydroxamic acids. The⁵⁷Fe Mossbauer spectra are discussed.The author is née Bose     

Reaction of Ru(PPh3)3Cl2 with arylazoimidazoles: spectral characterisation and redox studies of [bis-{N(1)-alkyl-2-(arylazo)imidazole}-bis-(triphenylphosphine)]-ruthenium(II) perchlorate

Ru(PPh₃)₃Cl₂ reacts with N(1)-alkyl-2-(arylazo)imidazoles, p-RC₆H₄N=NC₃H₂N₂X, [RaaiX, R = H(a), Me(b), Cl(c); X = Me(1), Et(2), Bz(3)] under refluxing conditions in EtOH to give [Ru(RaaiX)₂(PPh₃)₂](ClO₄)₂ · H₂O complexes (4–6). RaaiX is a bidentate chelator (N, N) with N(imidazole), N and N(azo), N donor centres. Three isomers are present in the mixture in which the pairs of PPh₃, N and N occupy cis–cis–trans, cis–trans–cis and cis–cis–cis, positions respectively. The isomers were identified by ¹H-n.m.r. spectra. Four signals are observed in the aliphatic zone for N(1)-X; two are of equal intensity at higher and the other two signals at lower in the ratio 1:0.3:0.2 suggesting the presence of cis–cis–cis, cis–trans–cis and cis–cis–trans-geometry. The complexes display the allowed t ₂(Ru) ^*(RaaiX) transition. Cyclic voltammetry indicates two consecutive Ru^III/II couples along with azo reductions.     

N-(2-吡啶基)-伯胺·二甲基合镓(Ⅲ)的制备及表征

通过2-甲酰基吡啶与胺缩合制得Schiff碱,经NaBH₄还原得到四个N-(2-吡啶甲基)芳胺(芳基=苯基,邻甲氧基苯基,对甲苯基及2-吡啶基),得到的芳胺及N-(2-吡啶乙基)甲胺与三甲基镓反应生成相应的N-(2-吡啶基)伯胺·二甲基合镓(Ⅲ)配合物。用元素分析、红外光谱、质子核磁共振、质谱等手段对配合物进行了结构鉴定和表征。     

Reactions of tungsten and molybdenum propargyl complexes with Co2(CO)8, Co4(CO)12, and Cp2Mo2(CO)4. A crossover study of formation of (CO)3 Cp(CO)2

The nature of the protonation reaction of (

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o(CO)₃ (M = Mo, W; R = Me, Ph, p-MeC₆H₄) (2) (obtained from (CO)₃CpMCH₂CCR (1) and Co₂(CO)₈) to give (CO)₃ Cp(CO)₂ (3) was further investigated by a crossover experiment. Thus, reaction of an equimolar mixture of 2b (M = W, Cp = η⁵-C₅H₅, R = Ph) and 2e (M = W, Cp = η⁵-C₅H₄Me; R = p-MeC₆H₄) with CF₃COOH affords only 3b (same M, Cp, and R as 2b) and 3e (same M, Cp, and R as 2e) to show an intramolecular nature of this transformation. Reaction of (CO)₃CpWCH₂CCPh (1b) with Co₄(CO)₁₂ was also examined and found to yield 2b exclusively. Treatment of 1 with Cp₂Mo₂(CO)₄ at 0–5°C provides thermally sensitive compounds, possibly (CO)₂Cp

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oCp(CO)₂ (5), which decompose at room temperature to give Cp₂Mo₂(CO)₆ as the only isolated product.     

Dissociative photoionization of Al2(Ch3)6 and Al2(Ch3)3Cl3 in the range 40–100 eV

Dissociation processes of the organoaluminum compounds Al₂(CH₃)₆ and Al₂(CH₃)₃Cl₃ have been studied in the range of valence and Al:2p core-level ionization by means of photoelectron–photoion and photoion–photoion coincidence techniques. The double-ionization threshold and the Al:2p core-ionization threshold of Al₂(CH₃)₆ are estimated to be about 30 and 80 eV

1 1 eV = 96.4853 kJ mol^?1.

respectively. The relative yields of the H⁺?Al⁺ and H⁺?CH_m,⁺ (m′ = 0–3) ion pairs are enhanced around the Al:2p core-ionization threshold of Al₂(CH₃)₆. The photoion–photoion coincidence intensities of Al₂(CH₃)₃Cl₃ are negligibly small throughout the energy range studied. The ratio of the relative yield of AlC₂H₆⁺ to that of Al⁺ increases smoothly through the Al:2p core-ionization and/or excitation region of Al₂(CH₃)₃Cl₃. The variation of the fragmentation pattern with photon energy is discussed in conjunction with the relevant electronic states.     

1-Selenolato-2-phenyl-o-carborane complexes of palladium(II) and platinum(II): Synthesis, spectroscopy and structures

The reactions of PhCb^oSeNa (Cb^o = o-C₂B₁₀H₁₀), prepared by reductive cleavage of Se-Se bond in (PhCb^oSe)₂ by NaBH₄ in methanol, with Na₂PdCl₄, MCl₂(PR₃)₂ and [M₂Cl₂(μ-Cl)₂(PR₃)₂] afforded a variety of complexes, viz., [Pd(SeCb^oPh)Cl] (1), [M(SeCb^oPh)₂(PR₃)₂], [M₂Cl₂(μ-SeCb^oPh)(μ-Cl)(PR₃)₂] (M = Pd, Pt) and [Pd₂Cl(SeCb⁰Ph)(μ-Cl)(μ-SeCb^oPh)(PEt₃)₂] (7) have been isolated. These complexes were characterized by elemental analyses and NMR (¹H, ³¹P, ⁷⁷Se, ¹⁹⁵Pt) spectroscopy. The structures of [Pd(SeCb^oPh)₂(PEt₃)₂] (2), [Pt(SeCb^oPh)₂(PMe₂Ph)₂] (3), [Pd₂Cl₂(μ-SeCb^oPh)(μ-Cl)(PMe₂Ph)₂] (5) and [Pd₂Cl(SeCb^oPh)(μ-Cl)(μ-SeCb^oPh)(PEt₃)₂] (7) were established by X-ray crystallography. The latter represents the first example of asymmetric coordination of selenolate ligands in binuclear bis chalcogenolate complexes of palladium and platinum. Thermolysis of [Pd(SeCb^oPh)₂(PEt₃)₂] (2) in HDA (hexadecylamine) at 330 °C gave nano-crystals of Pd₁₇Se₁₅.     

Tridentate chelate π-bonded complexes of rhodium(I), iridium(I), and iridium(III) and chelate σ-bonded complexes of nickel(II), palladium(II), and platinum(II) formed by intramolecular hydrogen abstraction reactions

2,2′-Bis(o-diphenylphosphino)bibenzyl, o-Ph₂PC₆H₄CH₂CH₂C₆H₄PPh₂-o (bdpbz), is dehydrogenated by various rhodium complexes to give the planar rhodium(I) complex

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, from which the ligand, 2,2′-bis(o-diphenylphosphino)-trans-stilbene (bdpps) can be displaced by treatment with sodium cyanide. The stilbene forms stable chelate olefin complexes with planar rhodium(I) and iridium(I) and with octahedral iridium(III). On reaction with halide complexes of nickel(II), palladium(II) or platinum(II), the stilbene ligands

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(R = Ph or o-CH₃C₆H₄) lose a vinyl proton in the form of hydrogen chloride to give chelate, planar σ-vinyls of general formula =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; X = Cl, Br, I) of high thermal stability; analogous methyl derivatives =CHC₆H₄PR₂-o) are obtained from Pt(CH₃)₂(COD) (COD = 1,5-cyclooctadiene) and the stilbene ligands. The bibenzyl also forms chelate σ-benzyls HCH₂C₆H₄PPh₂-o) (M = Pd, Pt; X = Cl, Br, I). The ¹H NMR spectra of the o-tolyl methyl groups in the compounds =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; R = o-CH₃C₆H₄) vary with temperature, probably as a consequence of interconversion of enantiomers arising from restricted rotation about the M---P and M---C bonds. Possible mechanisms for the dehydrogenation reactions are briefly discussed.     

Synthesis and spectroscopic studies of nickel(II) chalcogenolates derived from 1,2-diarylchalcogenolato-o-xylene

Nickel(II) chalcogenolate complexes [Ni(L-L)₂(dppe) Cl₂] (1, 2) have been prepared in high yields by reacting 1,2-diarylchalcogenolato-o-xylene, o-C₆H₄(CH₂EAr)₂ (E = Se or Te; Ar = Ph, C₆H₄OMe-4 and C₆H₄OEt-4), generated in situ, with Ni(dppe)Cl₂ [dppe = 1,2-bis(diphenylphosphino)ethane] in benzene. The structures were established by elemental analyses, molar conductance, i.r. and Raman, electronic ¹H- and ³¹P-n.m.r. and mass spectral data. The analytical and spectroscopic data are consistent with an octahedral geometry around nickel in (1) and (2). The ³¹P-n.m.r. spectra indicate their cis configuration in solution. This revised version was published online in June 2006 with corrections to the Cover Date.     

The cyclometallation of bis(di-p-methylbenzylphosphino)methane

The new diphosphine (4-MeC₆H₄CH₂)₂PCH₂P(4-MeC₆H₄CH₂)₂, L, was reacted with [MnMe(CO)₅] to give the novel cyclometallated compound [Mn{(4-MeC₆H₃CH₂)(4-MeC₆H₄CH₂)PCH₂P(4-MeC₆H₄CH₂)₂}(CO)₃], as the mer isomer, and with the ligand in a terdentate [C,P,P] fashion.     

Crystal structure and characterization of the bis(n-benzyl-benzotriazole-n3)-dichloro Co(II) complex: CoCl2(C6H4N3CH2Ph)2

The structure of [CoCl₂(C₆H₄N₃CH₂Ph)₂] has been determined by X-ray crystallography. It is also characterized by elemental analysis, IR and electronic spectroscopy, and by thermogravimetric differential thermal analysis. It crystallizes in the monoclinic system, space group C2/c, with lattice parameters a = 16.133(3) , b = 11.355(2) , c = 15.637(3) , = 117.22(3)°, and Z = 8. The crystal structure of the title compound consists of monomeric molecules of [CoCl₂(C₆H₄N₃CH₂Ph)₂] with slightly distorted tetrahedron geometry for the CoCl₂N₂ chromophore. The thermal gravimetry (TG) data indicate that there are four decomposition steps with five endothermic peaks. The final product of the thermal decomposition is CoCl₂. Elemental analysis and the electronic and IR spectra are in agreement with the structural data.Original Russian Text Copyright © 2004 by F. Jian, H. Wang, and H. XiaoTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 723–728, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pr2C6H3)

The compounds [MoCl(NAr)₂R] (R=CH₂CMe₂Ph (1) or CH₂CMe₃(2); Ar=2,6-Prⁱ₂C₆H₃) have been prepared from [MoCl₂(NAr)₂(dme)] (dme=1,2-dimethoxyethane) and one equivalent of the respective Grignard reagent RMgCl in diethyl ether. Similarly, the mixed-imido complex [MoCl₂(NAr)(NBu^t)(dme)] affords [MoCl(NAr)(NBu^t)(CH₂CMe₂Ph)] (3). Chloride substitution reactions of 1 with the appropriate lithium reagents afford the compounds [MoCp(NAr)₂(CH₂CMe₂Ph)] (4) (Cp=cyclopentadienyl), [MoInd(NAr)₂(CH₂CMe₂Ph)] (5) (Ind=Indenyl), [Mo(OBu^t)(NAr)₂(CH₂CMe ₂Ph)] (6), [MoMe(NAr)₂(CH₂CMe₂Ph)] (7), [MoMe(PMe₃)(NAr)₂(CH₂CMe ₂Ph)] (8) (formed in the presence of PMe₃) and [Mo(NHAr)(NAr)₂(CH₂CMe₂P h)](9). In the latter case, a by-product {[Mo(NAr)₂(CH₂CMe₂Ph) ]₂(μ-O)}(10) has also been isolated. The crystal structures of 1, 4, 5 and 10 have been determined. All possess distorted tetrahedral metal centres with cis near-linear arylimido ligands; in each case (except 5, for which the evidence is unclear) there are α-agostic interactions present.     

Synthesis and structural characterization of [(C5H4)SiMe2(N-t-Bu)]Ti[(o-C6H4)C(Ph)C(Ph)], generated via an alkyne-Ti benzyne coupling reaction

The thermolysis of [(C₅H₄)SiMe₂(N-t-Bu)]TiPh₂ in the presence of diphenylacetylene proceeds at 80 °C in cyclohexane solution with the sole formation of the titanacyclic complex [(C₅H₄)SiMe₂(N-t-Bu)]Ti[(o-C₆H₄)C(Ph)C(Ph)], which has been characterized by solution NMR measurements and X-ray crystallographic analysis. This reaction is accompanied by the elimination of benzene and presumably occurs via coupling of a titanium benzyne intermediate with diphenylacetylene. The two chemically inequivalent Ti-C bonds of 2.081(7) and 2.103(6) Å in [(C₅H₄)SiMe₂(N-t-Bu)]Ti[(o-C₆H₄)C(Ph)C(Ph)] reflect the increased electrophilicity of the d⁰ Ti(IV) center arising from the presence of the bifunctional ansa-cyclopentadienyldimethylsilylamido ligand.     

The substitution chemistry of RuCp* (temeda)Cl

Summary Halide abstraction from RuCp*(tmeda)Cl (1,tmeda=Me₂NCH₂CH₂NMe₂) with NaBPh₄ in CH₂Cl₂ leads to the formation of the sandwich complex RuCp*(⁶-C₆H₅BPh₃) (2). In the presence of CH₃CN (1 equiv.) and CO, however, the cationic complexes [RuCp*(tmeda)(CH₃CN)]⁺ (3) and [RuCp*(temeda)(CO)]⁺ (5) are obtained. In CH₃CN,tmeda is also replaced giving [RuCp*(CH₃CN)₃]⁺ (4). Complex1 reacts readily with terminal acetylenes HCCR, the products depending on the nature ofR (Ph, SiMe₃,n-Bu, COOEt). Thus, withR=Ph the ruthenacyclopentatriene complex RuCp*(,-C₄Ph₂H₂)Cl (6), withR=SiMe₃ the cyclobutadiene complex Ru(Cp*)(⁴-C₄H₂(1,2-SiMe₃)₂)Cl (7), and withR=n-Bu and COOEt the binuclear complexes (Cp*)RuCl₂(²:⁴-₂-C₄H₂(1,3-R)₂)Ru(Cp*) (8,9) are obtained. Furthermore, with diethyl maleate in the presence of 1 equiv. of LiCl,1 transforms into the new anionic complex Li[Ru(Cp*) (²-C₂H₂(COOEt)₂)Cl₂] (10). X-ray structures of2,3,4,7, and10 are included.

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Substitutionsreaktionen von RuCp*(tmeda)Cl

Zusammenfassung Chloridabspaltung von RuCp*(tmeda)Cl (1,tmeda=Me₂NCH₂CH₂NMe₂) mittels NaBPh₄ in CH₂Cl₂ führt zur Bildung des Halbsandwich-Komplexes RuCp*(⁶-C₆H₅BPh₃) (2), während in Gegenwart von CH₃CN oder CO die beiden kationischen Verbindungen [RuCp*(tmeda)(CH₃CN)]⁺ (3) und [RuCp*(tmeda)(CO)]⁺ (5) entstehen. In CH₃CN als Lösungsmittel wird sogartmeda unter Bildung von [RuCp*(CH₃CN)₃]⁺ (4) verdrängt. Komplex1 reagiert sehr leicht mit terminalen Alkinen HCCR, wobei die Produkte stark von der Natur des SubstituentenR (Ph, SiMe₃,n-Bu, COOEt) abhängen. Im Fall vonR=Ph entsteht der Ruthenacyclopentatrien-Komplex RuCp*(-C₄Ph₂H₂)Cl (6), mitR=SiMe₃ der Cyclobutadien-Komplex Ru(Cp*)(⁴-C₄H₂(1,2-SiMe₃)₂)Cl (7), und im Fall vonR=n-Bu und COOEt bilden sich die binuklearen Komplexe (Cp*)RuCl₂(²:⁴-₂-C₄H₂(1,3-R)₂)Ru(Cp*) (8,9). Überdies reagiert1 mit Maleinsäurediethylester in Gegenwart von LiCl zum neuen anionischen Komplex Li[Ru(Cp*) (²-C₂H₂(COOEt)₂)Cl₂] (10). Von2,3,4,7 und10 wurden die Kristallstrukturen bestimmt.

     

Synthesis and magnetic properties of copper(II) bis(phenylsulphinyl)ethane complexes

Summary Two Cu^II complexes, [Cu₂(-L)Cl₄·H₂O (1) and Cu₂(-L)Cl₄ (2) [-L and -L = meso- and rac-PhS(O)(CH₂)₂S(O)Ph, respectively], were synthesized and characterized by elemental analysis, i.r. spectra and molar conductances. In each case, the Cu^II ion bonds to the 557-01 moiety through oxygen, and may be bridged by the ligand (-L or -L). From magnetic moment measurements at room temperature and variable temperature magnetic susceptibilities, we suggest that complexes (1) and (2) exhibit weak ferromagnetic behaviour.     

Neutral,cationic and dicationic seven-coordinate complexes of molybdenum(II) and tungsten(II) containing mono- and bidentate nitrogen donor ligands

Summary The seven-coordinate complexes [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react with two equivalents of L(L=py, 4Me-py, 3Cl-py or 3Br-py) or one equivalent of NN {NN=2,2-bipyridine(bipy), 1,10-phenanthroline(phen), 5,6-dimethyl-1, 10-phenanthroline (5,6-Me₂-1, 10-phen), 5-Nitro-1, 10-phenanthroline (5-NO₂-1, 10-phen) and C₆H₄(o-NH₂)₂ (o-diam) (for M=Mo only)} in CH₂Cl₂ at room temperature to give the substituted products [MI₂(CO)₃L₂] or [MI₂(CO)₃(NN)] (1–17) in high yield. The compounds [MI₂(CO)₃(NCMe)₂] react with two equivalents of NN (for M=W, NN=bipy; for M=Mo, NN=phen) to give the dicationic salts [M(CO)₃(NN)₂]2I(18–19). The compounds [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react with two equivalents of 5,6-Me₂-1, 10-phen to yield the monocationic dicarbonyl compounds [MI(CO)₂(5,6-Me₂-phen)₂]I (20 and21). The dicationic mixed ligand complexes [M(CO)₃(bipy)(5,6-Me₂-phen)]2I (22 and23) are prepared by reacting [MI₂(CO)₃(NCMe)₂] with one equivalent of bipy, followed by anin situ reaction with 5,6-Me₂-1, 10-phen to afford the products22 and23. The complexes (1–23) described in this paper have been characterised by elemental analysis (C, H and N), i.r. spectroscopy and, in selected cases,¹Hn.m.r. spectroscopy. Magnetic susceptibility measurements show the compounds to be diamagnetic.