Transition‐Metal Complexes [(PMe3)2Cl2M(E)] and [(PMe3)2(CO)2M(E)] with Naked Group 14 Atoms (E=C–Sn) as Ligands; Part 1: Parent Compounds

The equilibrium geometries and bond dissociation energies of 16‐valence‐electron(VE) complexes [(PMe₃)₂Cl₂M(E)] and 18‐VE complexes [(PMe₃)₂(CO)₂M(E)] with M=Fe, Ru, Os and E=C, Si, Ge, Sn were calculated by using density functional theory at the BP86/TZ2P level. The nature of the M? E bond was analyzed with the NBO charge decomposition analysis and the EDA energy‐decomposition analysis. The theoretical results predict that the heavier Group 14 complexes [(PMe₃)₂Cl₂M(E)] and [(PMe₃)₂(CO)₂M(E)] with E=Si, Ge, Sn have C_2v equilibrium geometries in which the PMe₃ ligands are in the axial positions. The complexes have strong M? E bonds which are slightly stronger in the 16‐VE species 1ME than in the 18‐VE complexes 2ME . The calculated bond dissociation energies show that the M? E bonds become weaker in both series in the order C>Si>Ge>Sn; the bond strength increases in the order Fe<Ru<Os for 1ME , whereas a U‐shaped trend Ru<Os<Fe is found for 2ME . The M? E bonding analysis suggests that the 16‐VE complexes 1ME have two electron‐sharing bonds with σ and π symmetry and one donor–acceptor π bond like the carbon complex. Thus, the bonding situation is intermediate between a typical Fischer complex and a Schrock complex. In contrast, the 18‐VE complexes 2ME have donor–acceptor bonds, as suggested by the Dewar–Chatt–Duncanson model, with one M←E σ donor bond and two M→E π‐acceptor bonds, which are not degenerate. The shape of the frontier orbitals reveals that the HOMO?2 σ MO and the LUMO and LUMO+1 π* MOs of 1ME are very similar to the frontier orbitals of CO.     

Transition‐Metal Complexes [(PMe3)2Cl2M(E)] and [(PMe3)2(CO)2M(E)] with Naked Group 14 Atoms (E=C–Sn) as Ligands; Part 2: Complexation with W(CO)5

Density functional calculations at the BP86/TZ2P level were carried out to understand the ligand properties of the 16‐valence‐electron(VE) Group 14 complexes [(PMe₃)₂Cl₂M(E)] ( 1ME ) and the 18‐VE Group 14 complexes [(PMe₃)₂(CO)₂M(E)] ( 2ME ; M=Fe, Ru, Os; E=C, Si, Ge, Sn) in complexation with W(CO)₅. Calculations were also carried out for the complexes (CO)₅W–EO. The complexes [(PMe₃)₂Cl₂M(E)] and [(PMe₃)₂(CO)₂M(E)] bind strongly to W(CO)₅ yielding the adducts 1ME–W(CO)₅ and 2ME–W(CO)₅ , which have C_2v equilibrium geometries. The bond strengths of the heavier Group 14 ligands 1ME (E=Si–Sn) are uniformly larger, by about 6–7 kcal mol^?1, than those of the respective EO ligand in (CO)₅W‐EO, while the carbon complexes 1MC–W(CO)₅ have comparable bond dissociation energies (BDE) to CO. The heavier 18‐VE ligands 2ME (E=Si–Sn) are about 23–25 kcal mol^?1 more strongly bonded than the associated EO ligand, while the BDE of 2MC is about 17–21 kcal mol^?1 larger than that of CO. Analysis of the bonding with an energy‐decomposition scheme reveals that 1ME is isolobal with EO and that the nature of the bonding in 1ME–W(CO)₅ is very similar to that in (CO)₅W–EO. The ligands 1ME are slightly weaker π acceptors than EO while the π‐acceptor strength of 2ME is even lower.     

The syntheses and coordination properties of M(CO)3X(DAB) (M = Mn,Re; X = Cl,Br, I; DAB = 1,4-diazabutadiene)

M(CO)₅X (M = Mn, Re; X = Cl, Br, I) reacts with DAB (1,4-diazabutadiene = R₁N=C(R₂)C(R₂)′=NR′₁) to give M(CO)₃X(DAB). The ¹H, ¹³C NMR and IR spectra indicate that the facial isomer is formed exclusively. A comparison of the ¹³C NMR spectra of M(CO)₃X(DAB) (M = Mn, Re; X = Cl, Br, I; DAB = glyoxalbis-t-butylimine, glyoxyalbisisopropylimine) and the related M(CO)₄DAB complexes (M = Cr, Mo, W) with Fe(CO)₃DAB complexes shows that the charge density on the ligands is comparable in both types of d⁶ metal complexes but is slightly different in the Fe-d⁸ complexes. The effect of the DAB substituents on the carbonyl stretching frequencies is in agreement with the A′(cis) > A″ (cis) > A′(trans) band ordering.Mn(CO)₃Cl(t-BuNCHCHNt-Bu) reacts with AgBF₄ under a CO atmosphere yielding [Mn(CO)₄(t-BuNCHCHN-t-Bu)]BF₄. The cationic complex is isoelectronic with M(CO)₄(t-BuNCHCHNt-Bu) (M = Cr, Mo, W).     

Low oxidation state ruthenium chemistry : IV. The reactions of M(CO)2(PPh3)3 complexes (M = Fe,Ru) and the hydrogenation and isomerization of alkenes catalyzed by RuL(CO)2(PPh3)2 (L = H2, PPh3)

The complexes M(CO)₂(PPh₃)₃ (I, M = Fe; II, M = Ru) readily react with H₂ at room temperature and atmospheric pressure to give cis-M(H)₂(CO)₂(PPh₃)₂ (III, M = Fe;IV,M = Ru). I reacts with O₂ to give an unstable compound in solution, in a type of reaction known to occur with II which leads to cis-Ru(O₂)(CO)₂(PPh₃)₂(V). Even compound IV reacts with O₂ to give V with displacement of H₂; this reaction has been shown to be reversible and this is the first case where the displacement of H₂ by O₂ and that of O₂ by H₂ at a metal center has been observed. III and IV are reduced to M(CO)₃(PPh₃)₂ by CO with displacement of H₂; Ru(CO)₃- (PPh₃)₂ is also formed by treatment of IV with CO₂, but under higher pressure. Compounds II and IV react with CH₂CHCN to give Ru(CH₂CHCN)(CO)₂- (PPh₃)₂(VI) which reacts with H₂ to reform the hydride IV.cis-Ru(H)₂(CO)₂(PPh₃)₂(IV) has been studied as catalyst in the hydrogenation and isomerization of a series of monoenes and dienes. The catalysts are poisoned by the presence of free triphenylphosphine. On the other hand the ready exchange of H₂ and O₂ on the “Ru(CO)₂(PPh₃)₂” moiety makes IV a catalyst not irreversibly poisoned by the presence of air. It has been found that even Ru(CO)₂(PPh₃)₃(II) acts as a catalyst for the isomerization of hex-1-ene at room temperature under an inert atmosphere.     

Neutrale Bis‐Aziridin‐Komplexe des Typs [M(CO)3XAz2] (M = Mn,Re; X = Cl,Br; Az = N(H)C2H2Me2)

The pentacarbonylhalogene complexes [XM(CO)₅] (M = Mn, Re; X = Cl, Br) ( 1a – 2b ) react with 2,2‐dimethylaziridine by thermally induced substitution reaction to give the neutral bis‐aziridine complexes [M(X)(CO)₃Az₂] (Az = N(H)C₂H₂Me₂) ( 3a – 4b ). As a result of the X‐ray structure analyses, the metal atoms are octahedrally configurated in the facial arrangement; the intact three‐membered rings coordinate through their distorted tetrahedrally configurated N atoms. All compounds 3a – 4b are stable with respect to the directed thermal alkene elimination to give the corresponding nitrene complexes (CO)₄(X)M=NH; their IR, ¹H and ¹³C{¹H} NMR, and MS spectra are reported and discussed.     

Crystal structures and spectroscopic characterization of MBr2(CNXyl)n (M = Fe and Co,n = 4; M = Ni,n = 2; Xyl = 2,6‐dimethylphenyl), and of formally zero‐valent iron as a cocrystal of Fe(CNXyl)5 and Fe2(CNXyl)9

Structures and spectroscopic characterization of the divalent complexes cis‐dibromidotetrakis(2,6‐dimethylphenyl isocyanide)iron(II) dichloromethane 0.771‐solvate, [FeBr₂(C₉H₉N)₄]·0.771CH₂Cl₂ or cis‐FeBr₂(CNXyl)₄·0.771CH₂Cl₂ (Xyl = 2,6‐dimethylphenyl), trans‐dibromidotetrakis(2,6‐dimethylphenyl isocyanide)iron(II), [FeBr₂(C₉H₉N)₄] or trans‐FeBr₂(CNXyl)₄, trans‐dibromidotetrakis(2,6‐dimethylphenyl isocyanide)cobalt(II), [CoBr₂(C₉H₉N)₄] or trans‐CoBr₂(CNXyl)₄, and trans‐dibromidobis(2,6‐dimethylphenyl isocyanide)nickel(II), [NiBr₂(C₉H₉N)₂] or trans‐NiBr₂(CNXyl)₂, are presented. Additionally, crystals grown from a cold diethyl ether solution of zero‐valent Fe(CNXyl)₅ produced a structure containing a cocrystallization of mononuclear Fe(CNXyl)₅ and the previously unknown dinuclear [Fe(CNXyl)₃]₂(μ₂‐CNXyl)₃, namely pentakis(2,6‐dimethylphenyl isocyanide)iron(0) tris(μ₂‐2,6‐dimethylphenyl isocyanide)bis[tris(2,6‐dimethylphenyl isocyanide)iron(0)], [Fe(C₉H₉N)₅][Fe₂(C₉H₉N)₉]. The (M)C—N—C(Xyl) angles of the isocyanide ligand are nearly linear for the metals in the +2 oxidation state, for which the ligands function essentially as pure donors. The νCN stretching frequencies for these divalent metal isocyanides are at or above that of the free ligand. Relative to Fe^II, in the structure containing iron in the formally zero‐valent oxidation state, the Fe—C bond lengths have shortened, the C[triple‐bond]N bond lengths have elongated, the (M)C—N—C(Xyl) angles of the terminal CNXyl ligands are more bent, and the νCN stretching frequencies have shifted to lower energies, all indicative of substantial M(dπ)→π* backbonding.     

Complexes of di­methyl­tin dihalides with N‐methyl­pyrrolidinone,C12H24N2O2X2Sn (X = Cl,Br or I)

The single‐crystal X‐ray structure determinations of the title complexes, cis‐di­chloro‐trans‐di­methyl‐cis‐bis(N‐methyl­pyr­rolidin‐2‐one‐O)­tin(IV), [Sn(CH₃)₂Cl₂(C₅H₉NO)₂], cis‐di­bromo‐trans‐di­methyl‐cis‐bis(N‐methyl­pyrrolidin‐2‐one‐O)tin­(IV), [SnBr₂(CH₃)₂(C₅H₉NO)₂], and cis‐di­iodo‐trans‐di­methyl‐cis‐bis(N‐methyl­pyrrolidin‐2‐one‐O)­tin(IV), [Sn(CH₃)₂I₂(C₅H₉NO)₂], show that those tin complexes in which coordination of the lactam ligand to Sn^IV is realized via oxygen exhibit a distorted octahedral geometry.     

Photochemical reactions of M(CO)6 (M = Cr,Mo, W) with Ph2P(S)P(S)Ph2

New complexes {M(CO)₄[Ph₂P(S)P(S)Ph₂]} (M = Cr, Mo and W), (1a)–(3a), [(1a), M = Cr; (2a), M = Mo; (3a), M = W] and {M₂(CO)₁₀[-Ph₂P(S)P(S)Ph₂]} (M = Cr, Mo, W), [(1b)–(3b) [(1b), M = Cr; (2b), M = Mo; (3b), M = W]] have been prepared by the photochemical reaction of M(CO)₆ with Ph₂P(S)P(S)Ph₂ and characterized by elemental analyses, f.t.-i.r. and ³¹P-(¹H)-n.m.r. spectroscopy and by FAB-mass spectrometry. The spectra suggest cis-chelate bidentate coordination of the ligand in {M(CO)₄[Ph₂P(S)P(S)Ph₂]} and cis-bridging bidentate coordination of the ligand between two metals in (M = Cr, Mo and W).     

Chemical Bonding in Homoleptic Carbonyl Cations [M{Fe(CO)5}2]+ (M=Cu,Ag, Au)

Syntheses of the copper and gold complexes [Cu{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] containing the homoleptic carbonyl cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Au) are reported. Structural data of the rare, trimetallic Cu₂Fe, Ag₂Fe and Au₂Fe complexes [Cu{Fe(CO)₅}₂][SbF₆], [Ag{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] are also given. The silver and gold cations [M{Fe(CO)₅}₂]⁺ (M=Ag, Au) possess a nearly linear Fe-M-Fe’ moiety but the Fe-Cu-Fe’ in [Cu{Fe(CO)₅}₂][SbF₆] exhibits a significant bending angle of 147° due to the strong interaction with the [SbF₆]⁻ anion. The Fe(CO)₅ ligands adopt a distorted square-pyramidal geometry in the cations [M{Fe(CO)₅}₂]⁺, with the basal CO groups inclined towards M. The geometry optimization with DFT methods of the cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Ag, Au) gives equilibrium structures with linear Fe-M-Fe’ fragments and D₂ symmetry for the copper and silver cations and D_4d symmetry for the gold cation. There is nearly free rotation of the Fe(CO)₅ ligands around the Fe-M-Fe’ axis. The calculated bond dissociation energies for the loss of both Fe(CO)₅ ligands from the cations [M{Fe(CO)₅}₂]⁺ show the order M=Au (D_e=137.2 kcal mol⁻¹)>Cu (D_e=109.0 kcal mol⁻¹)>Ag (D_e=92.4 kcal mol⁻¹). The QTAIM analysis shows bond paths and bond critical points for the M−Fe linkage but not between M and the CO ligands. The EDA-NOCV calculations suggest that the [Fe(CO)₅]→M⁺←[Fe(CO)₅] donation is significantly stronger than the [Fe(CO)₅]←M⁺→[Fe(CO)₅] backdonation. Inspection of the pairwise orbital interactions identifies four contributions for the charge donation of the Fe(CO)₅ ligands into the vacant (n)s and (n)p AOs of M⁺ and five components for the backdonation from the occupied (n-1)d AOs of M⁺ into vacant ligand orbitals.     

Perfluormethyl‐Element‐Liganden. XLIII [1] Neue Synthesewege zu Zweikernkomplexen des Typs MM′(CO)8ER2X (M/M′ = Mn/Mn,Mn/Re,Re/Re; E = P,As; R = CF3, Me; X = Hal)

Perfluoromethyl Element Ligands. XLIII [1] Novel Synthetic Routes to Binuclear Complexes of the Type MM′(CO)₈ER₂X (M/M′ = Mn/Mn, Mn/Re, Re/Re; E = P, As; R = CF₃, Me; X = Hal, ) Mn(CO)₅I reacts with compounds of the type (CF₃)₂EAsMe₂ (E = P, As) as with the symmetric E₂(CF₃)₄ ligands in the first step with cleavage of the E‐As bond to yield the pro ducts (CO)₅MnE(CF₃)₂ and Me₂AsI. Reaction of the mononuclear complexes with excess of Mn(CO)₅I leads in good yields to the known dinuclear compounds (CO)₄Mn[E(CF₃)₂, I]Mn(CO)₄ and CO. Me₂AsI, the second product of the EAs cleavage, attacks the starting compound Mn(CO)₅I giving cis‐Mn(CO)₄I(AsMe₂I) and CO. This result encouraged us to thoroughly investigate the preparation of cis‐M(CO)₄X(EMe₂Y) complexes with most of the possible combinations of M = Mn, Re; E = P, As and X, Y = Cl, Br, I. An alternative route to these compounds was opened by the cleavage of the dinuclear manganese or rhenium halides M₂(CO)₈X₂ with the halophosphanes or ‐arsanes Me₂EY. This route was found to be especially advantageous for the preparation of the rheniumcarbonyl precursors, since milder conditions than for the CO‐substitution in Re(CO)₅X compounds are sufficient for the halogen‐bridged dinuclear complexes. Cis‐M(CO)₄X(EMe₂Y) complexes were used as precursors for the synthesis of novel homo‐ and heterodinuclear complexes of the type (CO)₄M(EMe₂, X)M′(CO)₄ by reacting the EY function with transition metal carbonylates Kat[M′(CO)₅] (Kat = Na, Bu₄N, Ph₄As). Thus the preparation of a wide range of complexes was possible, which before had been successfully prepared by the direct reaction of Mn₂(CO)₁₀ with Me₂EX only in few cases, e. g. with Me₂AsI. Spectroscopic investigations, using the CO valence frequencies and the ¹H‐NMR data of the ligands EMe₂Y or of the Me₂E bridges, were applied to study the influence of the variables M, M′, E, X, Y and Kat on the reactivity of the mononuclear complexes and the bonding situation in both the mono‐ and the dinuclear systems. The new compounds were characterized by spectroscopic (IR, NMR, MS) and analytic methods (C, H).     

Stereochemically nonrigid six-coordinate metal carbonyl complexes : IV. A 13C NMR investigation of cis-M(CO)4X2 and M′(CO)5X derivatives (M = Fe,Ru, Os; M′ = Mn,Re; X = H,I)

The ¹³C NMR spectra of cis-M(CO)₄X₂ and M′(CO)₅X (M = Fe, Ru, Os; M′ = Mn, Re; X = H, I) and cis·Os(CO)₄Me₂ are reported. Variable temperature spectra demonstrated the stereochemical nonrigidity of cis-Fe(CO)₄H₂ and the stereochemical rigidity of the rest. The carbonyl averaging process in cis-Fe(CO)₄H₂ occurs without ligand dissociation. Improved syntheses of some of these derivatives are also given.     

Perfluormethyl-Element-Liganden. Reaktionen der Metallhydride π-C5H5(CO)3 MH (M = Cr,Mo, W) mit Organoelement-Elementverbindungen des Typs R2EER2 und RE′ E′ R (E = As; E′ = S,Se; R = CH3 CF3)

Perfluoromethyl Element Ligands. XXX. Reactions of the Metal Hydridesπ-C₅H₅(CO)₃MH (M = Cr, Mo, W) with Organoelement-Element Compounds of the Type R₂ EER₂ and RE′ ′E ′R (E = P, As; E′ = S, Se; R = CH₃, CF₃) Cleavage reactions of R₂EER₂ and RE′E′R, respectively, (E = P, As; E′ = S, Se; R = CH₃, CF₃) with complexes π-C₅H₅(CO)₃MH (M = Cr, Mo, W) are used (a) to prepare known and novel complex subsituted phosphanes, arsanes, sulfanes, or selanes π-C₅H₅(CO)₃MER₂ (I) and π-C₅H₅(CO)₃ME′R (II), respectively, (b) to study the reactivity trends as a function of E, E′, R, and M (see Inhaltsübersicht). The tendency observed for the formation of the binuclear complexes [π-C₅H₅(CO)₂MER₂]₂ and [π-C₅H₅(CO)₂ME′R]₂, respectively, in following reactions of I and II increases in the series W ? Mo ≤ Cr and SeCF₃ < As(CF₃)₂ < SCF₃ ≈ P(CF₃)₂ < SeMe < AsMe₂ ?; PMe₂ ≈ SMe.     

Syntheses and structural characterizations of the octahedral boride clusters [Rh2Ru4H(CO)16−2x (nbd) x B] (x=1,2) and gold(I) phosphine derivatives (nbd=norbornadiene)

The reaction of less than one equivalent of [Rh₂Cl₂(nbd)₂] with [Ru₄H(CO)₁₂BH]⁻, which contains a semi-interstitial boron atom, yields the heterometallic boride clustercis-[Rh₂Ru₄H(CO)₁₂(nbd)₂B] which has been characterized by spectroscopic and X-ray diffraction methods. The cluster has an octahedral core, consistent with an 86 electron count. Deprotonation yields the conjugate basecis-[Rh₂Ru₄(CO)₁₂(nbd)₂B]⁻ which has been isolated and fully characterized as the [(Ph₃P)₂N]⁺ salt. There is little structural perturbation upon going fromcis-[Rh₂Ru₄H(CO)₁₂(nbd)₂B] tocis-[Rh₂Ru₄(CO)₁₂(nbd)₂B]⁻ and neither cluster shows a tendency for the formation of thetrans skeletal isomer in contrast to the analogous carbonyl clustercis-[Rh₂Ru₄(CO)₁₆B]⁻. If the reaction of [Rh₂Cl₂(nbd)₂] with [Ru₄H(CO)₁₂BH]⁻ is allowed to proceed for 30 min and [R ₃PAuCl] (R=Ph, C₆H₁₁, 2-MeC₆H₄) is then added, the clusterscis-[Rh₂Ru₄(CO)₁₂(nbd)₂B(AuPR₃)] andcis-[Rh₂Ru₄(CO)₁₄(nbd)B(AuPR₃)] are formed in yields that are dependent upon the initial reaction period. The single crystal structures ofcis-[Rh₂Ru₄(CO)₁₂(nbd)₂B(AuPPh₃)] andcis-[Rh₂Ru₄(CO)₁₄(nbd)B(AuPPh₃)] are reported. In contrast to their all-carbonyl analoguescis-[Rh₂Ru₄(CO)₁₆B(AuPR ₃)] (R=Ph or C₆H₁₁), the nbd derivatives do not undergocis →trans skeletal isomerism.     

Transition-Metal Complexes with Bidentate Ligands Spanning trans-Positions. IX. Preparation and 1H-NMR. Studies of complexes [MX2(1)] and [M′Cl(CO)(1)] (M = Pd,Pt; M′ = Rh,Ir; X = Cl,Br, I; 1 = 2, 11-Bis-(diphenylarsinomethyl)benzo[c]phenanthrene) and crystal and molecular structure of [PtCl2(1)]

The preparation of the bidentate ligand 2, 11-bis(diphenylarsinomethyl)benzo-[c]-phenanthrene ( 1 ) is described. This ligand reacts with appropriate substrates to give mononuclear square planar complexes of type [MX₂( 1 )] (M = Pd, Pt; X = Cl, Br, I) and [M′Cl(CO)( 1 )] (M′ = Rh, Ir) in which ligand 1 spans trans-positions. This is confirmed by the crystal structure of [PtCl₂( 1 )]. ¹H-NMR. spectra of the complexes are discussed and compared with those of model compounds trans-[MCl₂( 12 )₂] (M = Pd, Pt) and [M'Cl(CO)( 12 )₂] (M′ = Rh, Ir; 12 = AsBzPh₂).     

Heterodinuclear M1M2 Complexes (M1=Ni,Pd, Pt; M2=Rh,Ir) Supported by a Tetradentate Phosphine Ligand and Their Application for Hydrosilylation

A new series of cationic heterodinuclear complexes, [M¹M²Cl₂(meso-dpmppp)(RNC)₂]PF₆ (M¹=Ni, M²=Rh, R=^tBu ( 1 a ); M¹=Pd, M²=Rh, R=^tBu ( 2 a ), Xyl ( 2 b ); M¹=Pt, M²=Rh, R=^tBu ( 3 a ), Xyl ( 3 b ); M¹=Pd, M²=Ir, R=^tBu ( 4 a )), supported by a tetradentate phosphine ligand, meso-Ph₂PCH₂P(Ph)(CH₂)₃P(Ph)CH₂PPh₂ (meso-dpmppp), were synthesized by stepwise reactions of meso-dpmppp with NiCl₂ ⋅ 6H₂O or MCl₂(cod) (M=Pd, Pt), forming mononuclear metalloligands of [M¹Cl₂(meso-dpmppp)], and with [M²Cl(cod)]₂ (M²=Rh, Ir) and RNC (R=^tBu, Xyl) in the presence of [NH₄][PF₆]. The related neutral PdRh complex, [PdRhCl₃(meso-dpmppp)(XylNC)] ( 5 ), was also prepared. The structures of 1 – 5 were determined by X-ray analyses to contain two square planar d⁸ metal centers with face-to-face arrangement, where meso-dpmppp supports M¹ and M² metal ions in cis/trans-P,P coordination mode, combining cis-{M¹P₂Cl₂} and trans-{M²P₂(CNR)₂} units. Complexes 1 – 4 showed an intence characteristic absorption around 422–464 nm derived from Rh^I→RNC MLCT transition (HOMO→LUMO+1), which are influenced by changing M¹ (Ni^II, Pd^II, Pt^II) metal ions since HOMO composed of dσ* orbitals appreciably destabilized by changing M¹ from Ni to Pd, and Pt. The electronic structures of 1 a – 4 a were investigated on the basis of DFT calculations and NBO analyses to show weak but noticeable d⁸–d⁸ metallophilic interaction as empirical dispersion energy of 0.9–1.5 kcal/mol without M¹–M² covalent bonding interaction. In addition, 1 – 5 were utilized as catalysts for hydrosilylation of styrene, and the NiRh complex 1 a was found to show higher activity and chemo- and regioselectivity compared with 2 – 5 .     

Synthesis and characteristics of novel pentanuclear complexes [(OC)3Mn(η1,η5-C5H4)Fe(CO)2(η1,η5-C5H4CO2)]2M(η5-C5H5)2 (M=Ti, Zr)

The reaction of Cp₂MCl₂ complexes (M=Ti and Zr) with 2 equiv. of (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄COONa) results in the formation of the pentanuclear complexes (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄CO₂)]₂M(η⁵-C₅H₅)₂, which are characterized by IR and¹H NMR spectroscopy and cyclic voltammetry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1055–1058, May, 1997.     

Heteronukleare Metallatomcluster der Typen X4−n[SnM(CO)4P(C6H5)3]n und M2(CO)8 [μ-Sn(X)M (CO)4P(C6H5)3]2 aus Umsetzungen von SnX2 mit M2(CO)8[P(C6H5)3]2 (X = Halogen; M = Mn,Re; n = 2, 3)

Heteronuclear Metal Atom Clusters of the Types X_4?n[SnM(CO)₄P(C₆H₅)₃]_n and M₂(CO)₈[μ-Sn(X)M(CO)₄P(C₆H₅)₃]₂ by Reaction of SnX₂ with M₂(CO)₈[P(C₆H₅)₃]₂ (X = Halogene; M = Mn, Re; n = 2, 3) The compounds of the both types X_4?n[SnM(CO)₄P(C₆H₅)₃]_n (n = 3; M = Mn; X = F, Cl, Br, I. n = 2: M = Mn, Re; X = Cl, Br, I) and M₂(CO)₈[μ-Sn(X)M(CO)₄P(C₆H₅)₃]₂ (M = Mn; X = Cl, I. M = Re; X = Cl, Br, I) are prepared by reaction of SnX₂ with M₂(CO)₈[P(C₆H₅)₃]₂ (M = Mn, Re). Their IR frequencies are assigned. In Re₂(CO)₈[μ-Sn(Cl)Re(CO)₄P(C₆H₅)₃]₂ the central molecule fragment contains a planar Re₂Sn₂ rhombus with a transannular Re? Re bond of 316.0(2) pm. Each of the Sn^IV atoms is connected with the terminal ligands Cl and Re(CO)₄P(C₆H₅)₃. These ligands are in transposition with respect to the Re₂Sn₂ ring. The mean values for the remaining bond distances (pm) are: Sn? Re = 274.0(3); Sn? Cl = 243(1), Re? C = 176(5), Re? P = 242.4(9), C? O = 123(5). The factors with an influence on the geometrical shape of such M₂Sn₂ rings (M = transition metal) are discussed.     

Reactions of the cycloheptatrienyl complexes [MX(CO)2(η-C7H7)] (M=Mo, X=Br; M=W, X=I) with CNBu: X-ray crystal structure of [WI(CO)2(CNBu)2(η-C7H7)]

Reaction of [MX(CO)₂(η⁷-C₇H₇)] (M=Mo, X=Br; M=W, X=I) with two equivalents of CNBu^t in toluene affords the trihapto-bonded cycloheptatrienyl complexes [MX(CO)₂(CNBu^t)₂(η³-C₇H₇)] (1, M=Mo, X=Br; 2, M=W, X=I). The X-ray crystal structure of 2 reveals a pseudo-octahedral molecular geometry with an asymmetric ligand arrangement at tungsten in which one CNBu^t is located trans to the η³-C₇H₇ ring. Treatment of 2 with tetracyanoethene results in 1,4-cycloaddition at the η³-C₇H₇ ring to give [WI(CO)₂(CNBu^t)₂{η³-C₉H₇(CN)₄}], 3. The principal reaction type of the molybdenum complex 1 is loss of carbonyl and bromide ligands to afford substituted products [MoBr(CNBu^t)₂(η⁷-C₇H₇)] 4 or [Mo(CO)(CNBu^t)₂(η⁷-C₇H₇)]Br. Reaction of [MoBr(CO)₂(η⁷-C₇H₇)] with one equivalent of CNBu^t in toluene at 60°C affords [MoBr(CO)(CNBu^t)(η⁷-C₇H₇)], 5, which is a precursor to [Mo(CO)(CNBu^t)(NCMe)(η⁷-C₇H₇)][BF₄], 6, by reaction with Ag[BF₄] in acetonitrile. In contrast with the parent dicarbonyl systems [MoX(CO)₂(η⁷-C₇H₇)], complexes of the Mo(CO)(CNBu^t)(η⁷-C₇H₇) auxiliary, 5 and 6, do not afford observable η³-C₇H₇ products by ligand addition at the molybdenum centre.     

Metalated 1, 3‐Azaphospholes: η1‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)5 and μ2‐[(1, 3‐Benzazaphospholide‐P)(cyclopentadienide)nickel] Complexes

1H‐1, 3‐Benzazaphospholes react with M(CO)₅(THF) (M = Cr, Mo, W) to give thermally and relatively air stable η¹‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)₅ complexes. The ¹H‐ and ¹³C‐NMR‐data are in accordance with the preservation of the phosphaaromatic π‐system of the ligand. The strong upfield ³¹P coordination shift, particularly of the Mo and W complexes, forms a contrast to the downfield‐shifts of phosphine‐M(CO)₅ complexes and classifies benzazaphospholes as weak donor but efficient acceptor ligands. Nickelocene reacts as organometallic species with metalation of the NH‐function. The resulting ambident 1, 3‐benzazaphospholide anions prefer a μ₂‐coordination of the η⁵‐CpNi‐fragment at phosphorus to coordination at nitrogen or a η³‐heteroallyl‐η⁵‐CpNi‐semisandwich structure. This is shown by characteristic NMR data and the crystal structure analysis of a η⁵‐CpNi‐benzazaphospholide. The latter is a P‐bridging dimer with a planar Ni₂P₂ ring and trans‐configuration of the two planar heterocyclic phosphido ligands arranged perpendicular to the four‐membered ring.     

Organotransition-Metal Complexes of Multidentates 2. Synthesis and Allyl Bromination of N,N-Bis(3,5-Dimethylpyrazol-1-YL)Methane Derivatives of the Group VI Metal Carbonyls

N,N-Bis(3,5-dimethylpyrazol-1-yl)methane (H₂CPz'₂) reacts with the hexacarbonyls of chromium, molybdenum, and tungsten to give cis-(H₂CPz'₂)M(CO)₄ derivatives with M=Cr, Mo, W. The direct allyl bromination of these complexes is also investigated and only the molybdenum complex is converted into (H₂CPz'₂)Mo(CO)₂(π-C₃H₃)(Br).