Amidinato Complexes Research Articles

Single or Paired? Structure and Reactivity of PNP-Chromium(II) Hydrides.

The preparation and reactivity of a range of novel paramagnetic chromium(II) complexes supported by a carbazole-based PNP pincer ligand is reported. Deprotonation of the ligand precursors R(PNP)H (1R) and subsequent reaction with chromium(II) chloride led to the formation of square-planar chlorido complexes R(PNP)CrCl (2R). Further reaction with various alkylating agents resulted in the isolation of chromium alkyl complexes R(PNP)CrR' (3R-R') which were then hydrogenated to yield two rare examples of paramagnetic chromium(II) hydrides 4iPr and 4tBu. Both compounds were characterized by X-ray diffraction and paramagnetic NMR spectroscopy supported by a comprehensive DFT-supported assignment of the resonances. While the di(tert-butyl)phosphino PNP substituted complex 4tBu was found to exhibit a monomeric square-planar molecular structure, its isopropyl-substituted analog 4iPr forms a dimer, also indicated by a strong antiferromagnetic coupling of the chromium centers. The pronounced reactivity of these compounds toward C═X double bonds was demonstrated by reaction with benzophenone, N,N'-dicyclohexylcarbodiimide, and carbon dioxide, which gave the corresponding insertion products. The alkoxido complex 5iPr, the amidinato complex 6iPr, and the formato compound 7tBu were also characterized by X-ray diffraction.

Selective Intermolecular C–H Bond Activation: A Straightforward Synthetic Approach to Heteroalkyl Yttrium Complexes Containing a Bis(pyrazolyl)methyl Ligand

The reactions of bis(pyrazolyl)methanes CH2(C3HN2R2-3,5)2 (R = Me, tBu) with Y(CH2SiMe3)3(THF)2 and LY(CH2SiMe3)2(THF)n (L = amidopyridinate (Ap′), amidinate (Amd), tridentate amidinate bearing 2-methoxyphenyl pendant in a side arm (AmdOMe) and pentamethylcyclopentadienyl (Cp*); n = 0, 1) were investigated. CH2(C3HN2tBu2-3,5)2 turned out to be inert in these reactions, while less bulky CH2(C3HN2Me2-3,5)2 easily undergoes metalation by yttrium alkyls. The reaction of Y(CH2SiMe3)3(THF)2 with CH2(C3HN2Me2-3,5)2 regardless of the molar ratio of the reagents affords a homoleptic tris(alkyl) species, Y[CH(C3HN2Me2-3,5)2]3 (1). However, the reactions of equimolar amounts of LY(CH2SiMe3)2(THF)n and CH2(C3HN2Me2-3,5)2 occur selectively with replacement of a sole CH2SiMe3 fragment and afford the related heteroalkyl complexes LY(CH2SiMe3)[CH(C3HN2Me2-3,5)2](THF)n (L = Ap′, n = 1 (6); Amd, n = 0 (7); AmdOMe, n = 1 (8); Cp*, n = 1 (9)) in good yields. The second equivalent of CH2(C3HN2Me2-3,5)2 does not react with heteroalkyl yttrium complexes. The X-ray studies revealed that in complexes 1 and 6–9 the bis(pyrazolyl)methyl ligands are bound to the yttrium centers in a similar fashion via one covalent Y–C and two coordination Y–N bonds. Thermal decomposition of complexes 6–9 (C6D6, 80 °C) as evidenced by 1H NMR spectroscopy resulted in SiMe4 elimination, while no activation of the C–H bonds of bis(pyrazolyl)methyl ligands was detected. When 6 was treated with an equimolar amount of PhSiH3, only the YCH2SiMe3 bond selectively underwent σ-bond metathesis and a dimeric yttrium alkyl-hydrido complex, {Ap′Y[CH(C3HN2Me2-3,5)2](μ2-H)}2 (10), was formed. The reaction of 6 with 2,6-diisopropylaniline also resulted in the selective protonation of the YCH2SiMe3 bond and cleanly afforded alkyl-anilido complex Ap′Y(NHC6H3iPr2-2,6)[CH(C3HN2Me2-3,5)2](THF) (11). The ternary catalytic systems 6–9/borate/AliBu3 (borate = [HNMe2Ph][B(C6F5)4], [Ph3C][B(C6F5)4]; [Ln]:[borate]:[AliBu3] = 1:1:10) demonstrated moderate catalytic activity in isoprene polymerization; they allow quantitative conversion into polymer of up to 1000 equiv of monomer in 2–4 h. The best activity and 1,4-cis selectivity (83.5%) were demonstrated by amidinato complex 8.

Synthesis, structure and reactivity study of magnesium amidinato complexes derived from carbodiimides and N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-butadiene ligands.

We report an amidinato ligand-supported series of magnesium complexes obtained from the insertion of a magnesium-carbon bond into a carbon-nitrogen double bond of different carbodiimides and α-diimine ligands. The magnesium complexes [Mg(CH2Ph){CyN[double bond, length as m-dash]C(CH2Ph)NCy}]2 (), [Mg(CH2Ph){(i)PrN[double bond, length as m-dash]C(CH2Ph)N(i)Pr}]2 () and the homoleptic [Mg{(t)BuN[double bond, length as m-dash]C(CH2Ph)N(t)Bu}2] () (Cy = cyclohexyl, (i)Pr = isopropyl, (t)Bu = tert-butyl) were prepared by the reaction of dibenzyl magnesium [Mg(CH2Ph)2(Et2O)2] with the respective carbodiimides either in 1 : 1 or 1 : 2 molar ratio in toluene. The analogous reaction of [Mg(CH2Ph)2(Et2O)2] with the N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene (Dipp2DAD) ligand afforded the corresponding homoleptic magnesium complex [Mg{DippN[double bond, length as m-dash]C(CH2Ph)CH2NDipp}2] () (Dipp = 2,6 diisopropylphenyl) in good yield. The solid-state structures of magnesium complexes were confirmed by single-crystal X-ray diffraction analysis. It was observed that in each case, a magnesium-carbon bond was inserted into the carbon-nitrogen double bond of either carbodiimides or Dipp2DAD resulting in a monoanionic amido-imino ligand. In a further reaction between and N-aryliminopyrrolyl ligand 2-(2,6-(i)Pr2C6H3N[double bond, length as m-dash]CH)C4H3NH (ImpDipp-H) in 1 : 2 molar ratio, a new magnesium complex [Mg(ImpDipp)2{CyN[double bond, length as m-dash]C(CH2Ph)NHCy}] (), with one amidinato and two aryliminopyrrolyl ligands in the coordination sphere, was obtained in good yield. In contrast, the homoleptic magnesium complex reacted with one equivalent of N-aryliminopyrrolyl ligand (ImpDipp-H) to produce another mixed ligated magnesium complex [Mg{DippN[double bond, length as m-dash]C(CH2Ph)CH2NDipp}(ImpDipp)] (), with a benzylated DAD ligand and aryliminopyrrolyl ligands in the coordination sphere. Further reaction of complex with benzyl alcohol (PhCH2OH) afforded the third mixed ligated magnesium complex [Mg{DippN[double bond, length as m-dash]C(CH2Ph)CH2NDipp}(OCH2Ph)2] () in very good yield. The magnesium complexes were characterised using standard analytical/spectroscopic techniques and their solid-state structures were established by single-crystal X-ray diffraction analysis.

Divergent reactivity of nitric oxide with metal–metal quintuple bonds

Reactions of NO with the quintuple bonded chromium and molybdenum amidinate dimers, respectively, gave dichromium nitrosyl nitrito amidinato complexes, and the quadruple bonded dimolybdenum nitrito amidinato species with a paddlewheel configuration.

Extremely Bulky Amido and Amidinato Complexes of Boron and Aluminium Halides: Synthesis and Reduction Studies

An extremely bulky secondary amine, HN(Ar†)(SiPr3i) HL† (Ar† = C6H2{C(H)Ph2}2Pri−2,6,4) has been synthesised and deprotonated with KH in toluene, to afford the potassium amide [KL†(η6-toluene)], which was structurally authenticated. Reaction of this with BBr3 and AlBr3, reproducibly gave the crystallographically characterised amido bromo-borane, [L†B(H)Br], and aluminacycle, [AlBr2{κ2-C,N-N(H)(SiPr3i){C6H2[CPh2][C(H)Ph2]Pri-2,6,4}}], respectively, via ligand C–H activation processes. The known secondary amines, HN(Dip)(Mes) (HLMes) and HN(Dip)(Trip) (HLTrip) (Dip =2,6-diisopropylphenyl, Mes = mesityl, Trip = 2,4,6-triisopropylphenyl), have been structurally characterised, and deprotonated to give the in situ generated lithium amides, [Li(LMes)] and [Li(LTrip)]. Reaction of these with BBr3 and AlBr3 has given the amido group 13 element halide complexes, [LMesBBr2] and [LAlBr2(THF)] (L = LMes or LTrip), the crystal structures of all of which have been determined. Synthetic routes to two new bulky amidine pro-ligands, ArN = C(But)-N(H)Ar, Ar = C6H2{C(H)Ph2}2Me-2,6,4 (Piso*H) or C6H2Pr2i(CPh3)-2,6,4 (Piso″H), have been developed, and the compounds crystallographically characterised. Deprotonation of Piso″H gave the potassium amidinate, [K(Piso″)], which was reacted with BBr3 to give [(Piso″)BBr2]. Reaction of Piso″H with AlMe3 afforded [(Piso″)AlMe2], which, when treated with I2 yielded [(Piso″)AlI2], the crystal structure of which was determined. Reductions of all of the prepared amido and amidinato group 13 element(iii) halide complexes were attempted using a variety of reducing reagents, with a view to prepare boron(i) or aluminium(i) complexes. While these were not successful, this study does offer synthetic inorganic chemists a variety of new very bulky anionic N-donor ligands, and boron/aluminium halide complexes thereof, for use in their own research.

Evaluation of Homoleptic Guanidinate and Amidinate Complexes of Gadolinium and Dysprosium for MOCVD of Rare-Earth Nitride Thin Films

Metal−organic chemical vapor deposition (MOCVD) of thin films of two representative rare-earth nitrides is reported here for the first time. Four homoleptic, all-nitrogen-coordinated, rare-earth (RE) complexes were evaluated as precursors for the respective nitride thin film materials. Two guanidinato complexes [RE{(iPrN)2C(NMe2)}3] [RE = Gd (1), Dy (2)] and two amidinato complexes [RE{(iPrN)2CMe}3] [RE = Gd (3), Dy (4)] were compared and used either as single source precursors or together with ammonia for MOCVD of gadolinium nitride (GdN) and dysprosium nitride (DyN), respectively. The thermal properties of the precursors were studied and the fragmentation patterns were characterized by high-resolution electron impact−mass spectrometry (HR EI-MS). The obtained nitride films were investigated using a series of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), nuclear reaction analysis (NRA), Rutherford backscattering (RBS), and X-ray photoelectron spectroscopy (XPS). The f...

Bulky amidinato complexes and amidine adducts of Al, Ga and In halides

Reactions of a series of bulky amidinate salts M[RC(NAr) 2] (M = Li, Na or K; R = H, Fiso; Me, Aiso; Bu t , Piso; Ar = 2 , 6 - Pr 2 i C 6 H 3 ) with group 13 halides are reported. Treatment of the metal(I) halides, ‘GaI’ or InCl, with [Li(Fiso)] led to disproportionation reactions which gave the first gallium(II)-amidinate complex, [{GaI(Fiso)} 2] ( 7), in addition to the metal(III) complexes, [GaI(Fiso) 2] ( 8) and [InCl(Fiso) 2] ( 10). Moreover, the Ga(II) compounds 7 and [{GaI(Piso)} 2] ( 9) were synthesised in metathesis reactions between amidinate salts and [{GaI 2(NHCy 2)} 2] (Cy=cyclohexyl). Treating [AlMe 2(Aiso)], [{AlH 2(Piso)} 2] or [AlMe 2(Piso)] with iodine in toluene led to isolation of the Al(III) iodide complexes [AlI 2(Aiso)] ( 12), [AlI 3(AisoH)] ( 13) and [AlI 2(Piso)] ( 14). The adduct [GaCl 3(FisoH)] ( 16) was obtained from the reactions of either [Na(Fiso)] or FisoH with GaCl 3, whilst the amidinium salt [TripH 2][InBr 4] ( 17), (Trip = [TrC(NPr i ) 2] −, Tr = 9-triptycenyl) was isolated from the reaction of [Li(Trip)] with InBr 3. The X-ray crystal structures of 7, 9, 10, 13, 14, 16 and 17 are reported.

The reaction of amidinato(pyridine) complexes of molybdenum and tungsten with triethylborane adduct of N-heterocyclic carbene (NHC · BEt 3): Investigation on the reactivity of NHC · BEt 3 as carbene precursor toward transition metal complexes

The reaction of triethylborane adduct of N-heterocyclic carbene, NHC · BEt 3, (NHC = I i Pr = 1,3-diisopropylimidazol-2-ylidene (I i Pr · BEt 3; 1a), NHC = IMes = 1,3-dimesitylimidazol-2-ylidene (IMes · BEt 3; 1b)), which was prepared by the reaction of the corresponding imidazolium salt with one equivalent of LiBEt 3H, with amidinato(pyridine) complex, [M(η 3-allyl){η 2-(NPh) 2CH}(CO) 2(NC 5H 5)] (M = Mo; 2-Mo M = W; 2-W), was investigated. The reaction of compound 1 with complex 2 under toluene-reflux conditions resulted in the formation of carbene complex [M(η 3-allyl){η 2-(NPh) 2CH}(CO) 2(NHC)] (M = Mo, NHC = I i Pr; 3a-Mo, M = Mo, NHC = IMes; 3b-Mo, M = W, NHC = I i Pr; 3a-W, M = W, NHC = IMes; 3b-W). These complexes were characterized spectroscopically as well as by X-ray analyses. Complex 3a-Mo was formed in various solvents such as 1,2-dimethoxyethane (DME), 1,2-dichloroethane, and acetonitrile under refluxing conditions for 3 h. In toluene, 3a-Mo was obtained in a good yield by heating at 70 °C for only 20 min. Employment of NHC · BEt 3 ( 1) was found to afford convenient route for the introduction of the carbene ligand to the transition metal complexes.

Synthesis and some reactivity of amidinato(pyridine) complexes of molybdenum and tungsten formulated as [M(η 3-allyl)(amidinato)(CO) 2(NC 5H 5)

Bis(pyridine) complexes of molybdenum and tungsten, [M(η 3-allyl)Cl(CO) 2(NC 5H 5) 2] (M=Mo; 3-Mo, M=W; 3-W), reacted with an equimolar amount of lithiated amidinate, Li[(PhN) 2CR] (R=H; 4a-Li, R = CH 3; 4b-Li), to yield corresponding amidinato(pyridine) complexes, [M(η 3-allyl){(PhN) 2CR}(CO) 2(NC 5H 5)] (M=Mo, R=H; 5a-Mo, M=Mo, R=CH 3; 5b-Mo, M=W, R=H; 5a-W), as a yellow solid. The dissociation of pyridine ligand from the central metal in complexes 5a was observed in a polar solvent such as acetonitrile. In these cases, although the formation of amidinato(acetonitrile) complexes, [M(η 3-allyl){(PhN) 2CH}(CO) 2(NCMe)] (M=Mo; 6a-Mo, M=W; 6a-W), was suggested spectroscopically, isolation of complexes 6a was not successful but the re-formation of pyridine complexes 5a was observed. In the reactions of complexes 5a with PEt 3 and with P(OMe) 3, the substitution reactions easily took place to give [M(η 3-allyl){(PhN) 2CH}(CO) 2(PEt 3)] (M=Mo; 7a-Mo, M=W; 7a-W) and [M(η 3-allyl){(PhN) 2CH}(CO) 2{P(OMe) 3}] (M=Mo; 8a-Mo, M=W; 8a-W), respectively. These complexes were characterized spectroscopically as well as, in some cases, by X-ray analyses.

Synthesis of Novel Amidinato(amidine) Complexes of Molybdenum via Bis(amidine) Complexes

Abstract The molybdenum complex [Mo(η3-allyl)Cl(CO)2(NCMe)2] (1) reacted with two equivalents of amidines, ArN=C(R)NHAr (R = H, CH3; Ar = C6H5, p-CH3–C6H4) (2), to give corresponding bis(amidine) complexes, [Mo(η3-allyl)Cl(CO)2(amidine)2] (3). Upon a treatment of bis(amidine)molybdenum complexes (3) with a base, such as n-butyllithium, complexes (4) bearing both amidinato and amidine ligands were formed and isolated as a yellow solid. The amidine ligand in complexes 4 was easily substituted by PEt3 to give amidinato(phosphine) complexes of molybdenum (5) as a red solid. These complexes were characterized spectroscopically as well as by X-ray analyses.

Reaction of [M(η3-allyl)(η2-amidinato)(CO)2(pyridine)] complexes (M = Mo, W) with bidentate ligands: nitrogen donor vs. phosphorus donor

The reactivity of amidinato complexes of molybdenum and tungsten bearing pyridine as a labile ligand, [M(eta(3)-allyl)(eta(2)-amidinato)(CO)(2)(pyridine)](M = Mo; 1-Mo, M = W; 1-W), toward bidentate ligands such as 1,10-phenanthroline (phen) and 1,2-bis(diphenylphosphino)ethane (dppe) was investigated. The reaction of 1 with phen at ambient temperature resulted in the formation of monodentate amidinato complexes, [M(eta(3)-allyl)(eta(1)-amidinato)(CO)(2)(eta(2)-phen)](M = Mo; 2-Mo, M = W; 2-W), which has pseudo-octahedral geometry with the amidinato ligand coordinated to the metal in an eta(1)-fashion. The phen ligand was located coplanar with two CO ligands and the eta(1)-amidinato ligand was positioned trans to the eta(3)-allyl ligand. In solution, both complexes 2-Mo and 2-W showed fluxionality, and complex 2-Mo afforded allylamidine (3) on heating in solution. In the reaction of 1 with dppe at ambient temperature, the simple substitution reaction took place to give dppe-bridged binuclear complexes [{M(eta(3)-allyl)(eta(2)-amidinato)(CO)(2)}(2)(mu-dppe)](M = Mo; 5-Mo, M = W; 5-W), whereas mononuclear monocarbonyl complexes [M(eta(3)-allyl)(eta(2)-amidinato)(CO)(eta(2)-dppe)](M = Mo; 6-Mo, M = W; 6-W) were obtained under acetonitrile- or toluene-refluxing conditions. Mononuclear complex 6 was also obtained by the reaction of binuclear complex 5 with 0.5 equivalents of dppe under refluxing in acetonitrile or in toluene. The X-ray analyses and variable-temperature (31)P NMR spectroscopy of complex 6 indicated the existence of the rotational isomers of the eta(3)-allyl ligand, i.e., endo and exo forms, with respect to the carbonyl ligand. The different reactivity of complex 1 toward phen and dppe seems to have come from the difference in the pi-acceptability of each bidentate ligand.

Synthesis and catalytic properties of oxalic amidinato complexes

Download options Please wait... Supplementary files Crystal structure data TXT (68K) Article information DOI https://doi.org/10.1039/B010017J Article type Paper Submitted 15 Dec 2000 Accepted 22 Mar 2001 First published 15 May 2001 Download Citation J. Chem. Soc., Dalton Trans., 2001, 1761-1767 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Synthesis and catalytic properties of oxalic amidinato complexes C. Chen, L. H. Rees, A. R. Cowley and M. L. H. Green, J. Chem. Soc., Dalton Trans., 2001, 1761 DOI: 10.1039/B010017J To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Chi-Tien Chen Leigh H. Rees Andrew R. Cowley Malcolm L. H. Green

N,N′-Unsubstituted amidinato metallacycle complexes of Group 13 metal alkyls: the crystal structure of trimeric [{Me 2Al(μ-HNCPhNH)} 3

The amidinato complexes [Me 2ML] (L=HNCPhNH, M=Al, Ga, In; L=HNCBu t NH, M=Ga) result from the reaction of the trialkylmetal with an equimolar amount of the amidine. MS data indicate that the complexes exist as dimers or trimers in the gas phase. X-ray crystallographic studies on [{Me 2Al(μ-HNCPhNH)} 3] ( 1) reveal a novel trimeric structure in the solid state, with bridging benzamidinato ligands, and a 12-membered metallacycle. Reaction of InMe 3 with two moles of benzamidine yields a cyclic imidoylamidinato derivative with a six-membered [InNCNCN] ring.

Living Polymerization of Carbodiimides Initiated by Copper(I) and Copper(II) Amidinate Complexes

Various catalysts for the polymerization of carbodiimide have been investigated. In early studies, anionic polymerization techniques were employed, but the products obtained were low molecular weight oligomers. More recently, a living route using titanium(IV) complexes as initiators has been employed and the high molecular weight polymers obtained exhibit a well-ordered helical, extended-chain conformation. However, the titanium complexes are sensitive to high temperatures and the presence of oxygen or water. Herein, we report that more robust catalysts based on copper(I) and copper(II) complexes also initiate living carbodiimide polymerizations. The tolerance of these complexes to impurities is illustrated by the fact that they cleanly initiate the polymerization of carbodiimides under air and oxygen. They are even active in the presence of water, but both molecular weights and yields tend to be lower than in dry solvents. It has been shown that the catalytic activity of a copper(II) amidinato complex is...

Complexes of the platinum metalsXLV. Synthesis and x-ray crystal structure of hexacarbonyl bis (μ- N,N′-diphenylacetamidinato)diruthenium (I/I)

The ruthenium(I) amidinato complex [Ru{PhNC(Me)NPh}(CO) 3] 2 has been prepared by heating [Ru 3(CO) 12] with the free amidine, PhNC(Me)NHPh, in boiling benzene under a carbon monoxide atmosphere, and by heating [{Ru(O 2CMe)(CO) 2} 2] n with free amidine and triethylamine in acetonitrile under carbon monoxide. The structure of [Ru{PhNC(Me)NPh}(CO) 3] 2 has been determined by X-ray diffraction methods. The binuclear complex has two Ru(CO) 3 units linked by an RuRu bond [2.714(1) Å] and a cis pair of bridging amidinato ligands. Variable temperature 1H and 13C { 1H} NMR spectra show evidence of hindered rotation about the Nphenyl bonds of the amidinate ligands. An attempt to prepare the corresponding propionamidinate derivative gave a product which is tentatively formulated as [Ru{PhNC(Et)NPh}(CO) 2(HO 2CMe)] 2 on the basis of analytical and spectroscopic evidence.

Complexes of the platinum metals. Part 43. N,N′-diphenylamidinato derivatives of ruthenium, osmium and iridium

N,N′-Diphenylamidines PhNC(R)–NHPh (R = H, Me, Et or Ph) reacted with the precursors [MH2(CO)(PPh3)3], [MH(Cl)(CO)(PPh3)3] and [M(O2CCF3)2(CO)(PPh3)2]·nMeOH (M = Ru, n= 0.75; or Os n= 0.33) in boiling benzene to afford the amidinato complexes [MH{PhNC(R)NPh}(CO)(PPh3)2], [MCl{PhNC(R)NPh}(CO)(PPh3)2] and [M(O2CCF3){PhNC(R)NPh}(CO)(PPh3)2] respectively. The hydrides [MH{PhNC(R)NPh}(CO)(PPh3)2] have also been obtained by oxidative addition of amidines to [Ru(CO)3(PPh3)2] and by treatment of the precursors [MH(Cl)(CO)(PPh3)3] with amidines in the presence of an excess of base (NEt3). The trifluoroacetates [M(O2CCF3)2(CO)(PPh3)2]·nMeOH reacted with amidines in the presence of NEt3 to afford the hydrides [MH{PhNC(R)NPh}(CO)(PPh3)2](M = Ru, R = H; M = Os, R = H, Me, Et or Ph) or the bis(amidinato) complexes [M{PhNC(R)NPh}2(CO)(PPh3)](M = Ru; R = Me, Et or Ph). Reactions of the dichlorides [MCl2(PPh3)3] with amidines and base (NEt3) in boiling toluene containing traces of alcohol were accompanied by a carbonyl-abstraction reaction leading to formation of [MH{PhNC(R)NPh}(CO)(PPh3)2] and/or [MCl{PhNC(R)NPh}(CO)(PPh3)2]. The hydrides [MH{PhNC(R)NPh}(CO)(PPh3)2] are also obtained when [RuH2(PPh3)4] or [OsH4(PPh3)3] reacts with amidines in boiling toluene (containing a trace of alcohol) or in 2-methoxyethanol. The carbonyl abstractions are remarkable in that they have no parallel in the corresponding reactions involving the related triazenide (PhNNNPh–) and carboxylate (RCO2–) ligands even when neat alcohols are used as solvents. Reactions of mer-[IrH3(PPh3)3], [IrHCl2(PPh3)3]–NEt3 and [IrHCl2(PPh3)3] with amidines in boiling benzene or toluene afforded [IrH2{PhNC(R)NPh}(PPh3)2], [IrH(Cl){PhNC(R)NPh}(PPh3)2] and [IrCl2{PhNC(Ph)NPh}(PPh3)2] respectively.

Amidinato complexes of the platinum metals and an avid carbonyl abstraction reaction

Platinum metal hydrido and trifluoroacetato complexes react with N,N′-diphenylamidines, PhNC(R)NHPh (R = H, Me, Et, Ph), giving the amidinato derivatives Ru{PhNC(R)NPh} 2(CO)(PPh 3), MX{PhNC(R)NPh}(CO)(PPh 3) 2 and IrX 2{PhNC(R)NPh}(PPh 3) 2 (M = Ru, Os; X = H, Cl; X 2 = H 2, Cl 2 or HCl). The reactions of RuH 2(PPh 3) 4 and OsH 4(PPh 3) 3 with amidines are accompanied by an avid alcohol decarbonylation reaction to form the carbonyls MH{PhNC(R)NPh}(CO)(PPh 3) 2.

Ph–C(NSiMe3)2]2FeCl; ein Amidinatokomplex von Eisen(III) mit verzerrt trigonal-bipyramidaler Struktur / [Ph–C(NSiMe3)2]2FeCl; an Amidinato Complex of Iron(III) with a Distorted Trigonal-Bipyramidal Structure

The amidinato complex [Ph—C(NSiMe3)2]2FeCl has been prepared by the reaction of FeOCl with the amidine Ph—C(NSiMe3)[N(SiMe3)2] in acetonitrile/THF in the form of dark red moisture sensitive single crystals. The complex was characterized by IR spectroscopy, by its 57Fe-Mössbauer spectra, as well as by an X-ray structure determination. Space group PI, Z = 2, 3180 observed unique reflections, R = 0.068. Lattice dimensions at —80°C: a = 1210.4(2), b = 1272.7(3), c = 1316.0(3) pm; α = 67.81(3)°, β = 76.14(3)°, γ = 67.19(3)°. The complex has a molecular structure in which the iron atom is surrounded in a distorted trigonal-bipyramidal fashion with the chlorine ligand and two nitrogen atoms of different amidinato chelates in equatorial positions. The remaining nitrogen atoms occupy the apical positions.

Synthese und Kristallstruktur des Amido-Palladats (PPh4)2[Pd2Cl4(NH2)2] · CH2Cl2 und des Benzamidin-Palladats PPh4{ [Ph– C(NH2)(NH)]PdCl3} · CH3CN / Synthesis and Crystal Structure of the Amido Palladate (PPh4)2[Pd2Cl4(NH2)2] · CH2Cl2 and of the Benzamidine Palladate PPh4{[Ph—C(NH2)(NH)]PdCl3} · CH3CN

Orange crystals of (PPh4)2[Pd2Cl4(NH2)2] have been prepared by the reaction of (PPh4)2[Pd2Cl6] with N,N,N′-tris(trimethylsilyl)benzamidine in boiling acetonitrile in the presence of water, and orange brown crystals of PPh4{[Ph—C(NH2)(NH)]PdCl3} by the reaction of the amidinato complex PPh4[Ph—C(NSiMe3)2PdCl2] with HCl gas in acetonitrile solution. The complexes were characterized by IR spectroscopy as well as by X-ray structure determinations. (PPh4)2[Pd2Cl4(NH2)2] · CH2Cl2: Space group PĪ, Z = 1, 2784 observed unique reflections, R = 0.043. Lattice dimensions at —60 °C: a = 1053.3(4), b = 1081.1(4), c = 1249.2(4) pm, α = 102.90(2)°, β = 110.44(2)°, γ = 102.23(2)°. The compound consists of PPh4 + ions and centrosymmetric anions [Pd2Cl4(NH2)2]2- with bridging chlorine atoms and terminal amido groups. PPh4{[Ph—C(NH2)(NH)]PdCl3} -CH3CN: Space group C2/c, Z = 8, 1183 observed unique reflections, R = 0.033. Lattice dimensions at —60 °C: a = 3106.7(6), b = 1059.0(1), c = 1818.0(4) pm, β = 90.98(2)°. The compound consists of PPh4 + ions, [Ph—C(NH2)(NH)PdCl3]-ions, and included CH3CN molecules. In the anion the benzamidine ligand is bound via the nitrogen atom of the imido group.

Ag2[Ph – C(NSiMe3)2]2 und Au2[Ph – C(NSiMe3)2]2: Amidinatokomplexe mit kurzen Metall–Metall-Abständen / Ag2[Ph—C(NSiMe3)2]2 and Au2[Ph—C(NSiMe3)2]2: Amidinato Complexes with Short Metal—Metal Distances

The amidinato complexes of silver(I) and gold(I), M2[Ph—C(NSiMe3)2]2, have been prepared by the reaction of N,N,N′-tris(trimethylsilyl)benzamidine with AgO2CCH3, and ClAuCO, respectively, in acetonitrile suspensions. Both complexes were characterized by IR spectroscopy as well as by X-ray structure determinations. Ag2[Ph—C(NSiMe3)2]2: Space group P1̄, Z = 2 (6408 observed unique reflexions, R = 0.023). Lattice dimensions at —10 °C: a = 1132.5(5), b = 1221.4(6), c = 1407.9(8) pm, α = 107.85(3), β = 106.63(4), γ = 91.54(3)°. Au2[Ph—C(NSiMe3)2]2: Space group P1̄, Z = 2 (6654 observed unique reflexions, R = 0.043). Lattice dimensions at —73 °C: a = 1119.6(6), b = 1219.0(8), c = 1391.7(9) pm, α = 108.74(4), β= 106.70(5), γ = 91.49(4)°. The compounds, which are isotypical, form dimeric molecules with short metal—metal contacts of Ag···Ag = 265.5(2) and Au···Au = 264.6(2) pm and two chelating amidinato ligands with Ag—N bond lengths of (averaged) 212.4(2) pm and Au—N bond lengths of 206.0(7) pm.