Liquid Injection Field Desorption Ionization Mass Spectrometry of Cyclic Metal Carbonyl Complexes with Tetra-Antimony Ligands

Reactions of (norbornadiene)Cr(CO)₄ or cis-(piperidine)₂Mo(CO)₄ with R₂Sb-SbR₂, and cyclo-(R′Sb)_n (R′ = Et, n-Pr; n = 4, 5) give the complexes cyclo-[M(CO)₄(R₂Sb-SbR′- SbR′-SbR₂)] (1: M = Cr, R = Me, R′= Et; 2: M = Mo, R = Et, R′ = Et; 3: M = Mo, R = Et, R′ = n-Pr). Not accessible to established characterization methods, the oily, extremely reactive unpurified mixture of 3 with scrambled ligands was characterized by mass spectrometry using liquid injection field desorption ionization (LIFDI).      

Metalmetal bonded triazenido compounds : II. Compounds with M = RhI,IrI; R = Me,aryld and X = Cl,Br, I Cl,Br, I

Complexes

(M = Rh, X = Cl, M = Ir, X = Cl, Br, I and R = CH₃, R′ = CH₃, p-tolyl) have been made by the reaction of (Ph₃P)₂(CO)MX with

. The proposed structure is analogous to that of the related copper derivatives and contains a five-membered ring in which an M^I to Ag^I donor bond is bridged by an azenido group, while the halide atom X has migrated from M^I to Ag^I.Carbon monoxide at 1 atm reacts rapidly and quantitatively with the iridium compounds to give novel acyltriazenido compounds {Ph₃P(CO)₂ - Ir[OCN(R)N=NR′]} (R = CH₃, p-tolyl; R′ = CH₃, p-tolyl).     

The preparation of fluxional tetrahydrides, (R  H or Me) and their reactions with CO,ButNC or HBr

The cyclometallated monohydrides

(R  H or Me) react with NaOPrⁱ/PrⁱOH/H₂ to give fluxional tetrahydrides, probably

. These are highly fluxional having magnetically equivalent hydridic hydrogens, even at ---100°C. When treated with HBr,

, gives

and with CO it gives a mixture of complexes which are probably

(2 isomers) and

. When treated with Bu^tNC this tetrahydride undergoes similar reactions but another (major) product is formed which appears to be binuclear and fluxional and is probably of type

, with four bridging hydrogens.     

Cumulative author index

Reactions of L₂M(CO)X (L = Ph₃P, PhMe₂P, Ph₃As; M = Rh^I, Ir^I and X = Cl, Br, I) with

(n = 4 for R = R′ = CH₃; n = 2 for R = R′ = p-tolyl and for R = CH₃ and R′ = p-tolyl) afford the novel complexes

in which three-coordinate Cu^I is directly bonded to the five-coordinate metal atom M^I. The M^I→Cu^I donor bond is bridged by the azenido group. The halide atom X has migrated from the metal atom to the copper atom.Possible mechanisms for the formation of these complexes and of related new formamidine and trifluoroacetate compounds are considered and the properties of the complexes are discussed.     

Direktsynthese von orthometallierten Ketonen des Typs RCO (o-C6H4)Mn(CO)4−nLn (R = Alkyl- und Arylrest,n = 0, 1, 2, L = Ligand)

Direct Synthesis of Orthometallated Ketones of the Type RCO(o-C₆H₄)Mn(CO)_4?nL_n (R = Alkyl and Aryl Groups, n = 0, 1, 2, L = Ligand) The starting materials of the type RMn(CO)_5?nL_n und (C₆H₅)₂ Hg react to the products of the type RCO(o-C₆H₄)Mn(CO)_4?nL_n[n = 0, R = Ch₃, C₂H₅, C₃H₇, C₆H₅,CH₂; R = C₆H₅, n = 1, L = E(C₆H₅)₃, E = P, As, Sb; R = C₆H₅, n = 2, L = P(OR′)₃, R′ = C₆H₅, CH₃, C₂H₅, C₃H₇]. Steps of their complex reaction pathway are proposed. These orthometallated substances have been characterized by means of ¹H-n.m.r., i.r. and u.v. spectroscopic measurements. The determination of the molecular structure of the two compounds RCO(o-C₆H₄)Mn(CO)₃L [R = C₂H₅, L = CO; R = C₆H₅, L = As(C₆H₅)₃] show that both contain a planar heterocyclic five-membered ring of the type .     

Preparation and properties of the formamidino complexes [M(π-C5H5){HC(NR)2}(CO)2] (M = molybdenum or tungsten; R = aryl or alkyl)

The preparation and properties of the complexes [M(π-C₅H₅){HC(NR)₂}CO)₂] (M = Mo, W; R = aryl or alkyl) are reported. The complex [Mo(π-C₅H₅){HC(N-p-tolyl)₂}(CO)₂] could be prepared by (a) reaction of MoCp(CO)₃Cl with M′{HC(N-p-tolyl)₂} (M′ = K, Ag or Cu); (b) irradiation of MoCp(CO)₃Cl with HC(HN-p-tolyl)N-p-tolyl); and (c) reaction of [MoCp(CO)₃]₂ with M′{HC(N-p-tolyl)₂} (M′ = Ag or Cu). The several routes to this complex give indications of the mechanisms of formation. The structure of these complexes and the bonding nature of the metal with the formamidino group is discussed on basis of the ¹H and ¹³C NMR and IR spectra.Reaction of N,N′-dimethyl formamidine with MCp(CO)₃Cl gave the complex [M(π-C₅H₅){HC(NMe)N(CO)Me}(CO)₂], containing a carbonyl inserted between the metal and the formamidino group. Irradiation of this carbamoyl complex caused decarbonylation, yielding the complex [M(π-C₅H₅){HC(NMe)₂}CO)₂].     

Addition von kationischen Lewis‐Säuren [M′Ln]+ (M′Ln = Fe(CO)2Cp,Fe(CO)(PPh3)Cp,Ru(PPh3)2Cp,Re(CO)5, ${1 \over 2}$ Pt(PPh3)2, W(CO)3Cp an die anionischen Thiocarbonyl‐Komplexe [HB(pz)3(OC)2M(CS)]− (M = Mo,W; pz = 3,5‐dimethylpyrazol‐1‐yl)

Addition of Cationic Lewis Acids [M′L_n]⁺ (M′L_n = Fe(CO)₂Cp, Fe(CO)(PPh₃)Cp, Ru(PPh₃)₂Cp, Re(CO)₅, Pt(PPh₃)₂, W(CO)₃Cp to the Anionic Thiocarbonyl Complexes [HB(pz)₃(OC)₂M(CS)]⁻ (M = Mo, W; pz = 3,5‐dimethylpyrazol‐1‐yl) Adducts from Organometallic Lewis Acids [Fe(CO)₂Cp]⁺, [Fe(CO)(PPh₃)Cp]⁺, [Ru(PPh₃)₂Cp]⁺, [Re(CO)₅]⁺, [ Pt(PPh₃)₂]⁺, [W(CO)₃Cp]⁺ and the anionic thiocarbonyl complexes [HB(pz)₃(OC)₂M(CS)]⁻ (M = Mo, W) have been prepared. Their spectroscopic data indicate that the addition of the cations occurs at the sulphur atom to give end‐to‐end thiocarbonyl bridged complexes [HB(pz)₃(OC)₂MCSM′L_n].     

Mononuclear and heterodinuclear phenanthrolinedione complexes of <Emphasis Type="Italic">d</Emphasis>- and <Emphasis Type="Italic">f</Emphasis>-block elements

1,10-Phenanthroline-5,6-dione (Phd) complexes of group 3 and lanthanide elements having formulae Ln(hfac)₃(Phd) (Ln = Y, Eu, Yb; hfac = hexafluoroacetylacetonate) were synthesised and characterised. Complexes of d-block elements of the type [MCl(Phd)(p-cymene)]⁺ (M = Ru, Os) were also prepared. In all these species, coordination of the polydentate ligand occurs by the N-donor moieties, as indicated by DFT calculations. The novel compounds were tested, together with fac-ReBr(Phd)(CO)₃, as precursors for the preparation of heterobimetallic d/f derivatives. The reaction of the rhenium complex with yttrium or lanthanide anhydrous triflate salts led to the formation of the complexes ReBr(CO)₃(N,N′-Phd-O,O′)Ln(OTf)₃(THF) (Ln = Y, Eu, Yb), where the trivalent ions interacted with the quinonoid moiety. The redox properties of the rhenium centre were strongly affected by the coordination of Ln(OTf)₃, as observed by comparing the cyclic voltammetry measurements carried out on fac-ReBr(Phd)(CO)₃ and on ReBr(CO)₃(N,N′-Phd-O,O′)Y(OTf)₃.     

Nickel(II) complexes of the type [RM(oxam)MR] (oxam: oxalamidinate, R=n-butyl, n-hexyl): the first binuclear n-alkyl nickel complexes

The reaction between one equivalent of [(acac)Ni(A)Ni(acac)] (A: N¹,N²-bis(2-pyridylmethyl)-N³,N⁴-bis-(2,4,6-trimethylphenyl)oxalamidinate) and two equivalents of R-Li (R=n-butyl; n-hexyl) results in the formation of the binuclear complexes [(R-Ni)(A)(Ni-R)] (1: R=n-butyl: 2=n-hexyl). Both compounds were characterized by ¹H- and ¹³C-NMR spectroscopy, elemental analysis, and mass spectroscopy. X-ray single diffraction studies of single crystals of 1 and 2 show that symmetrical binuclear complexes are formed in which the two Ni(II) centers are connected by the oxalamidinato bridging ligand A in a planar-square environment. No agostic interactions between the β-hydrogens of the n-alkyl groups and the metal centers were observed. DTA- and DTG-investigations show, that 1 and 2 are surprisingly thermally stable (decomposition temperature of 1: 188 °C under formation of butenes). Heating up a 1:1 mixture of 1 and 2 in toluene results in the formation of octane, decane and dodecane indicating an intermolecular transfer reaction of the n-alkyl-groups in solution. CV measurements display that the oxam complexes [(R-M)(A)(M-R)] (M=Ni, R=CH₃ (3), Ph (4), CCH (6), CCPh (7); M=Pd, R=CH₃ (5) are reversibly reduced in two steps indicating electronic interactions between the two metal centers.     

Molecular geometry and electronic structures of stable organic derivatives of divalent germanium and tin [(\operatorname{Me} _3 \operatorname{Si} )_2 \operatorname{N} {\kern 1pt} ---{\kern 1pt} Me_2 ]_n (M = Ge, n = 1; M = Sn, n = 2): a theoretical study

The molecular geometry and electronic structure of stable organic derivatives of divalent germanium and tin, [(Me₃Si)₂N-M-OCH₂CH₂NMe₂]_n (M = Ge (4), n = 1; M = Sn (5), n =2) and their isomers with broken (4a, 5a) and closed (4b, 5b) intramolecular coordination bonds M←NMe₂, were studied by the density functional (PBE/TZ2P/SBK-JC) and NBO methods. Factors responsible for stability of their dimers 4c and 5c were established. Dimerization of 5b in the gas phase is a thermodynamically favorable process (ΔG ⁰ = ?2.1 kcal mol^?1) while that of 4b is thermally forbidden (ΔG ⁰ = 10.1 kcal mol^?1), which is consistent with experimental data. The M←NMe₂ coordination bond energies, ΔE ⁰, were found to be ?5.3 and ?8.6 kcal mol^?1 for M = Ge and Sn, respectively. NBO analysis showed that the metal atoms M in molecules 4 and 5 are weakly hybridized. The lone electron pairs of the M atoms have strong s-character while vacant orbitals of these atoms, LP* M, are represented exclusively by the metal np_z-AOs. The strongest orbital interactions between subunits in dimers 4c and 5c involve electron density donation from the lone electron pairs of oxygen atoms (LP O) to the LP* M orbitals.     

Binuclear metal carbonyl dab complexes : VII. A 13C NMR investigation of MM′(CO)6(DAB) complexes (M = M ′ = Fe,Ru; M = Mn,Re and M′ = Co; DAB = 1,4-diazabutadiene). Dynamic behaviour of σ2-N, σ2-N′, η2-C=N coordinated dab in MnCo(CO)6(DAB) and local scrambling of the carbonyl groups

The ¹³C NMR spectra of MM′(CO)₆(DAB) complexes (M = M′ = Fe, Ru; M = Mn, Re and M′ = Co; DAB = 1,4-diazabutadiene) show very characteristic features which are directly related with the bonding mode of the DAB ligand to the binuclear metal carbonyl fragment. In these complexes the DAB ligand is σ²-N, μ²-N′, η²-C=N or σ²-N, σ²-N′, η²-C=N coordinated. Chemical shifts of about 175 ppm are observed for the σ-coordinated imine fragments and about 60 or 80 ppm for the η²-C=N coordinated imine fragments.In MnCo(CO)₆[diacetylbis(cyclopropylimine)] the DAB ligand is fluxional, and the changes in the spectra when recorded at various temperatures can be interpreted in terms of an exchange between the σ- and π-coordinated part of the DAB ligand.The homodinuclear M₂(CO)₆(DAB) complexes (M = Fe or Ru) contain M(CO)₃ fragments on which the carbonyl groups are involved in a local scrambling process with very different activation parameters (T_c = ?50°C and +85°C).MCo(CO)₆(DAB) complexes (M = Mn, Re), which contain a semi-bridging carbonyl group according to the crystal structure, show rapid interchange of this carbonyl group with the terminal carbonyl groups on cobalt. The electronic balance is kept in equilibrium by an internal compensation within the DAB ligand.     

Conformations and properties of <Emphasis Type="Italic">O</Emphasis>-Alkyl-<Emphasis Type="Italic">S</Emphasis>-(2-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dialkylamino)-ethylmethylthiophosphonates

Conformers of the biologically active compounds CH₃P(O)(OR)(SCH₂CH₂NR ₂ ^′ ), where (I) R = i-C₄H₉, R′ = C₂H₅ and (II) R = C₂H₅, R′ = i-C₃H₇, are calculated within the AM1 level of theory. The elongated and twisted forms with maximum and minimum distances between a nitrogen atom and those of a phosphorus tetrahedron, respectively, and bearing a syn and anti oriented alkoxy group relative to a phosphoryl oxygen, are studied. It is found that the differences between the energy, electronic, and geometric parameters of these forms are apparent in differences between their properties, e.g., the ability to participate in complexation and protonation, reactions that to some extent simulate the interaction between a substance and a biological object.     

Fluxional nickel(II)- and palladium (II)-triazenido (C5H5)(L)(RN3R)M complexes; Evidence for a triplet-state intermediate

Summary The (⁵-C₅H₅)(L)(RN₃R)Ni and (⁵-C₅H₅)(PPh₃)(RN₃R)Pd compounds, with L = PPh₃, CO, CNR, and RN₃R = diaryltriazenido anion, were prepared. The bonding mode of the triazenido ligand is monodentate in the (⁵-C₅H₅)(PPh₃)(RN₃R)M phosphine compounds. The carbonyl and isonitrile groups are inserted into the nickel-nitrogen bond and a five-membered heteronuclear ring is formed in (⁵-C₅-C₅H₅)(L)(RN₃R)Ni, when L= CO and CNR.Most compounds are fluxional, involving site exchange of the triazenidoaryl-groupsvia intermediates with a chelating bonding mode of the triazenido ligand. The (⁵-C₅H₅)(PPh₃)(RN₃R)Ni compound shows anomalous solution paramagnetism, that is correlated with the fluxional mechanism. The temperature dependence of contact shifts in the n.m.r. spectrum was determined and E-values were calculated.     

Über Chalkogenolate. 140. Untersuchungen über Dialkylester von Chalkogenokohlensäuren. 3. S,Se-Dialkyldithiomonoselenocarbonate Existenzbeweis von Alkylselenoxanthaten [S2C?SeR]−

On Chalcogenolates. 140. Studies on Dialkyl Esters of Chalcogenocarbonic Acids. 3. S,Se-Dialkyl Dithiomonoselenocarbonates. Evidence for the Existence of Alkyl Selenoxanthates [S₂C? SeR]^? The esters RSe? CS? SR′ with R = R′ = C₂H₅, ⁿC₃H₇ as well as with R = ⁿC₃H₇ and R′ = C₂H₅ have been produced by three different methods. The compounds have been characterized by means of electron absorption, infrared, nuclear magnetic resonance (¹H, ¹³C, and ⁷⁷Se), and mass spectra. The unstable alkyl selenoxanthates M[S₂C? SeR], where M = Na, K and R = C₂H₅, ⁿC₃H₇, are formed by reaction of carbon disulfide with the corresponding alkane selenolate. Freshly prepared they react with alkyl iodides R′I to yield RSe? CS? SR′.     

Selektive Darstellung zweifach diorganophosphido-verbrückter Metallatetrahedrane [Re2(MPR3)2(μ-PR2)2(CO)6] mit Re2M2-Metallgerüst (M = Au,Ag)

Selective Preparation of Twofold Diorganophosphido-bridged Metallatetrahedranes [Re₂(MPR₃)₂(μ-PR₂)₂(CO)₆] with Re₂M₂ Metal Core (M = Au, Ag) The reaction of the in situ prepared salt Li[Re₂(AuPR)(μ-PR₂)(CO)₇Cl] (R = R′ = Cy ( 1 a ), R = Cy, R′ = Ph ( 1 b ), R = Ph, R′ = Cy ( 1 c ), R = Ph, R′ = Et ( 1 d ), R = Ph, R′ = Ph ( 1 e )) with one equivalent HPR in methanolic solution at room temperature yields the neutral cluster complexes [Re₂(AuPR)(μ-PR₂)(CO)₇(ax-HPR) (R = R′ = R″ = Cy ( 2 a ), Ph ( 2 b ), R = R′ = Cy, R″ = Et ( 2 c ), R = Cy, R′ = R″ = Ph ( 2 d ), R = Cy, R′ = Ph, R″ = Et ( 2 e ), R = R″ = Ph, R′ = Et ( 2 f ), R = Ph, R′ = Cy, R″ = Et (2 g)). Photochemically induced these complexes react in the presence of the organic base DBU in THF solution to give the doubly phosphido bridged anions Li[Re₂(AuPR)(μ-PR₂)(μ-PR)(CO)₆], which were characterized as salts PPh₄[Re₂(AuPR)(μ-PR₂)(μ-PR)(CO)₆] (R = R′ = R″ = Ph ( 3 a ), R = R′ = Ph, R″ = Cy ( 3 b ), R = Ph, R′ = Cy, R″ = Et ( 3 c ), R = R″ = Ph, R′ = Et ( 3 d )). These precursor complexes 3 then react with one equivalent of ClMPR (M = Au, Ag) to doubly phosphido bridged metallatetrahedranes [Re₂(MPR₃)₂(μ-PR₂)(μ-PR)(CO)₆] (M = Au, R = R′ = R″ = Ph ( 4 a ), M = Au, R′ = Et, R = R″ = Ph ( 4 b ), M = Au, R = R′ = Ph, R″ = Cy ( 4 c ), M = Au, R = Cy, R′ = Ph, R″ = Et ( 4 d ), M = Ag, R = R′ = R″ = Ph ( 4 e )). All isolated cluster complexes were characterized and identified by the following analytical methods: NMR- (¹H, ³¹P) and ν(CO) IR-spectroscopy and, additionally, complexes 2 b , 4 a and 4 e by X-ray structure analysis.     

Electronic Structure and Relative Stabilities of 10- and 12-Vertex. <Emphasis Type="Italic">Closo</Emphasis>and <Emphasis Type="Italic">Nido</Emphasis>-Heteroborane Clusters of Ga,Ge, and As Elements

A DFT method with the B3LYP functional and the 6-311++G(d,p) diffuse basis set is used to predict geometries, relative stabilities, electronic structures, and the bonding of closo- and nido-Ga_mB_n–mH _n ^2? , Ge_mB_n–mH _n ^m?2 , and As_mB_n–mH _n ^{2 m?2} (n = 10, 12 and m = 1, 2) Clusters are obtained by replacing BH with isolobal GaH, GeH⁺, and AsH²⁺ fragments, keeping the same skeleton electron pairs (SEP). Based on the polyhedral skeletal electron pairs theory (PSEPT), closo and nido structures are predicted and can be of significant interest for experimentalists working in the field of heteroboranes. Different cluster stabilities are studied according to Gimarc′s and Williams′ rules, where our calculations show that the monosubstituted clusters deviate from these rules, giving rise to open structures. As₂B₈H _n ²⁺ as 10-vertex structures lead to nido-type clusters, however, Ge_mB_n–mH _n ^m?2 (n = 10, 12 and m = 1, 2) give rise to closo isomers with close energies. All optimized structures exhibit large HOMO–LUMO gaps suggesting a good kinetic stability, thus predicting their isolation and characterization.     

Zur ursache der extremen 31P-NMR-verschiebungen von phosphinidenkomplexen

Phosphinidene complexes RP[ML_n]₂ (R = univalent residue; L_nM = 16 electron fragment e.g. (CO)₅Cr, Cp(CO)₂Mn) show extremely paramagnetic ³¹P NMR shifts (884 to 1362 ppm). The values of these NMR shifts are strongly correlated with the energy of the electroic ππ^* transition in

π-systems. The large paramagnetic ³¹P NMR shifts is caused by the small

HOMO-LUMO separation specific for these compounds.     

Preparation and characterization of molybdenum and tungsten compounds with diazabutadiene ligands constructed from amino esters and glyoxal: Crystal structures of meso and C2-symmetric isomers of Mo(CO)4(dab-asp(OMe)-OMe)

The title compounds were prepared by heating solutions of ester protected amino acids (H-l-Ala-OEt, H-β-Ala-OEt, H-l-Val-OMe, GABA-OMe, H-l-Asp(OMe)-OMe) and glyoxal in the presence of M(CO)₄(pip)₂ (M=Mo, W). The resulting novel complexes, M(CO)₄(dab-xxx-OR) (dab=diazabutadiene), contain an N,N′-diimine ligand and were characterized by ¹H- and ¹³C-NMR, IR, and UV-vis measurements. The low energy band in the visible portion of the electronic spectrum is assigned to a MLCT transition and exhibits solvatochromism. The valine, alanine and aspartic ester derivatives have C₂ symmetry resulting from the C₂ symmetry of the ligand. The reaction of the alanine and aspartic amino esters in the presence of NEt₃ produces diastereomeric mixtures caused by racemization at the amino acid α-carbon. Racemization is not observed during the formation of the valine derivatives. The crystal structures of (R,S)-Mo(CO)₄(dab-asp(OMe)-OMe) (5-RS), and (S,S)-Mo(CO)₄(dab-asp(OMe)-OMe) (5-SS), were determined. The structure of 5-RS confirms that racemization at the α-carbon occurred. 5-SS has C₂ symmetry.     

Über Chalkogenolate. 138. Untersuchungen über Dialkylester von Chalkogenokohlensäuren 1. O,Se-Dialkylmonoselenocarbonate

On chalcogenolates. 138. Studies on Dialkyl Esters of Chalcogenocarbonic A cids. 1. O, Se-Dialkyl Monoselenocarbonates The esters RSe? CO? OR′ with R = R′ = C₂H₅ as well as with R = ⁿC₃H₇ and R′ = CH₃, C₂H₅ have been prepared by reaction of sodium alkane selenolates with alkyl esters of chloroformic acid. The compounds have been characterized by means of electron absorption, infrared, nuclear magnetic resonance (¹H, ¹³C, and ⁷⁷Se), and mass spectra.