Cobalt-pyridine bond strength in RCo[N,N′-ethylenebis(salicyclideneaminato)] (pyridine) R=Me,Et,n-Pr,i-Pr,n-Bu,i-Bu

The use of differential scanning calorimetry has provided enthalpies,H (298 K), of the dissociation reactions RCo(salen) (pyridine) (c) RCo(salen) (c)+pyridine(g)R=Me 34.5, Et 21.9,n-Pr 12.8,i-Pr 11.1,n-Bu 8.3 andi-Bu 13.5 kJ mol^–1

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Zusammenfassung Mit Hilfe der Differential-Scanning-Kalorimetrie wurden die EnthalpienH(298 K) der Dissoziationsreaktionen RCo(salen)(Pyridin)(c) RCo(saleo)(c)+Pyridin(g) bestimmt: R=Me 34,5, Et 21,9,n-Pr 12,8,i-Pr 11,1,n-Bu 8,3 undi-Bu 13,5 kJ·mol^–1.

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(298 K) : R() () R ()+() R R = – 34,5; – 21,9; - –12,8; - 11,1; - –8,3 13,5 · ^–1.

     

Zur Synthese der Heptaphospha-nortricyclane R3P7R = Et,i-Pr,n-Bu,i-Bu,SiH2Me,SiH3, Et2P–SiMe2

Concerning the Synthesis of the Heptaphospha-nortricyclanes R₃P₇ R = Et, i-Pr, n-Bu, i-Bu, SiH₂Me, SiH₃, Et₂P—SiMe₂ The preparative access to the compounds Et₃P₇ 1 ,i-Pr₃P₇ 2 ,n-Bu₃P₇ 3 ,i-Bu₃P₇ 4 , (H₃Si)₃P₇ 5 , (MeH₂Si)₃P₇ 6 , and (Et₂P—SiMe₂)₃P₆ 7 through the reaction of Li₃P₇ · 3 DME with either EtBr, i-PrBr, n-BuBr, H₃SiI, MeSiH₂Br or Et₂P—Sime₂Cl, respectively, is described. At 20°C the compounds 1 to 4 are yellow-greenish, viscid liquids (viscosity increases with the size of R), which are well soluble in ethers and non-polar solvents. 5 forms colorless crystals, which (similar to those of 6 ) decompose, when exposed to sunlight. 6 and 7 are generated quantitatively, these compounds, however, cannot be isolated undecomposed. While the formation of 1 occurs quantitatively via the red intermediate Li₂EtP₇, it is possible to isolate Li(i-Pr)₂P₇ from the residue of the reaction leading to i-Pr₃P₇. This Li-phosphide is said to cause the formation of higher, P-rich phosphanes like i-Pr₃P₉. Treatment of Li₃P₇ with (Me₃C)₃SiBr does not yield [(Me₃C)₃Si]₃P₇. The ratio R₃P₇(sym.): R₃P₇(asym.) — being 1:3 in Et₃P₇ or Me₃P₇-shifts with increasing size of R, favouring the symmetrical isomer. There are no hints for the formation of an asymmetrical isomer in (H₃Si)₃P₇ — as already known from (Me₃Si)₃P₇, where an asymmetric isomer does not exist either.     

Variable trends in R-X bond dissociation energies (R = Me, Et, i-Pr, t-Bu)

[structure: see text] High level ab initio molecular orbital calculations confirm experimental indications that the effect of alkyl substituents (R = Me, Et, i-Pr, t-Bu) on R-X bond dissociation energies varies considerably according to the nature of X. A simple qualitative explanation in terms of valence-bond theory is presented, highlighting the increasing importance of the stabilization of R-X by the ionic R(+)X(-) configuration for electronegative X substituents (such as F, OH, and OCH(3)).     

Synthesis, characterization, and structural studies of mixed-ligand diorganotin esters, [R2Sn(OP(O)(OH)Ph)(OS(O)2R1)]n [R = n-Bu, R1 = Me (1), n-Pr(2); R = Et, R1 = Me (3)] with 1D and 3D coordination polymeric motifs

Mixed-ligand diorganotin esters, [R 2Sn(OP(O)(OH)Ph)(OS(O) 2R (1))] n [R = n-Bu, R (1) = Me ( 1), n-Pr ( 2); R = Et, R (1) = Me ( 3)], have been synthesized by reacting the tin precursors, R 2Sn(OR (1))OS(O) 2R with an equimolar amount of phenylphosphonic acid under mild conditions (room temperature, 6-8 h, CH 2Cl 2). These have been characterized by IR, multinuclear ( (1)H, (13)C{ (1)H}, (31)P, and (119)Sn) NMR, and single crystal X-ray diffraction studies. The asymmetric unit of 1 is comprised of a tetramer with four crystallographically unique tin atoms. The structure reveals a central eight-membered (Sn-O-S-O) 2 cyclic ring with two exocyclic tin atoms, which results from micro 3-binding of the two methanesulfonate groups. The remaining two sulfonates are monodentate and contribute in O...HO(P) hydrogen bonding. The molecular structure is extended into a 3D coordination polymer with the aid of hydrogenphenylphosphonate group on each tin atom, acting in a micro 2-O 2P mode and forms a series of eight-membered (Sn-O-P-O) 2 rings in the structural framework. 2 and 3 are isostructural and represent linear 1D coordination polymers via micro 2-binding mode of both alkanesulfonate and hydrogenphenylphosphonate groups.     

Synthesis and X-ray and Spectral Study of the Compounds [Q4N]2[Fe2(S2O3)2(NO)4] (Q = Me,Et, n-Pr,n-Bu)

Iron nitrosyl complexes with general formula [Q₄N]₂[Fe₂(S₂O₃)₂(NO)₄] (Q = Me, Et, n-Pr, n-Bu) were synthesized by the exchange reaction of K₂[Fe₂(S₂O₃)₂(NO)₄] with tetraalkylammonium bromides. The molecular and crystal structure of [(CH₃)₄N]₂[Fe₂(S₂O₃)₂(NO)₄] were studied by X-ray diffraction analysis. The iron atom in the four-membered cycle of the [2Fe–2S] anion is bound to another Fe atom and to two sulfur atoms and is coordinated by two nonequivalent NO groups, each bridging sulfur atom being bound to the SO₃group. The structurally equivalent iron atoms are in the state Fe^1–(S= 1/2). The Mössbauer spectroscopy method shows that the complexes are diamagnetic due to the strong Fe–Fe bond. It is found that the SO₃group provides higher stability of the thiosulfate anion than the anion in Roussin's red salt [Fe₂S₂(NO)₄]^2–.     

Nitrile Cluster Compounds [(M6X12)X2(RCN)4] (M=Nb, Ta; X=Cl, Br; R=Et, n-Pr, n-Bu)

Three new series of mixed-ligand clusters of the [(M₆X₁₂)X₂(RCN)₄] (M=Nb, Ta; X=Cl, Br; R=Et, n-Pr, n-Bu) composition have been prepared. It is supposed that four nitrile molecules and two halogen atoms are coordinated to the terminal octahedral coordination sites of the [M₆X₁₂]²⁺ unit.     

Synthesis,characterization and in vitro antitumour activity of diorganotin bisxanthates [R2Sn(S2COR′)2] (R=Me,Et, nBu,Ph; R′=Et,iPr, Hex) and crystal structure of bis(O-ethyldithiocarbonato)diphenyltin(IV)

A series of diorganotin bisxanthate compounds, [R₂Sn(S₂COR′)₂] (R=Me, Et, nBu, tBu, and Ph; R′?Et, iPr and cHex) have been prepared and characterized by spectroscopic methods (IR, NMR and FAB MS). The xanthate ligands chelate the R₂Sn moieties forming disparate Sn–S bonds leading to skew-trapezoidal biypramidal tin atom geometries. The crystal structure of a representative compound, [Ph₂Sn(S₂COEt)₂], confirms the spectroscopic results and shows the tin atom to be coordinated by two asymmetrically chelating xanthate ligands [Sn–S(1) 2.486(1), Sn–S(2) 3.052(1) Å and Sn–S(3) 2.484(1), Sn–S(4) 3.220(1) Å] with the two phenyl substituents lying over the weaker Sn–S interactions so that C–Sn–C is 126.5(1)°. Crystal data for [Ph₂Sn(S₂COEt)₂]: monoclinic space group P2₁/n: a=9.645(1), b=23.723(3), c=9.798(2) Å, ß=100.23(1)°, V=2206.2 ų, Z=4; 2708 data refined to final R 0.023. A selection of these compounds has been evaluated for activity against the L1210 mouse leukaemia cell line.     

Synthesis and crystal structure of two new Bi(III) complexes {(Me2NCS2)3Bi}2 and {[(CH2)5NCS2]2BiI}2

Six bismuth(III) complexes containing dithio-ligands formulated as (R₂NCS₂)₃Bi [R₂NCS₂M?=?Me₂NCS₂Na, C₄H₈NCS₂Na, Bz₂NCS₂Na] and [(R₂NCS₂)₂BiI]₂ [R₂NCS₂M?= C₅H₁₀NCS₂Na, ⁿ Bu₂NCS₂Na, OC₄H₈NCS₂Na] have been obtained by reactions of bismuth(III) halides with dithiocarbamate ligands in 1?:?2 or 1?:?3 stoichiometry. All compounds were characterized by elemental and IR analyses. The crystal structures of complexes 1 and 4 have been determined by X-ray single crystal diffraction. The structure analyses reveal that Bi^III in complex 1 adopts a distorted pentagonal–pyramidal coordination, due to its stereochemically active lone pair of electrons. A long Bi?·?S contact of 3.218 (3)?Å leads to dimeric associations of molecules in the crystal structure. The structure of complex 4 is six-coordination with a distorted octahedral configuration. Intramolecular S?·?S weak interactions contribute to the stability and lead to a one-dimensional chain structure.     

Synthesis and X-ray crystal structure of complexes Cp(CO)2MnP(SR)3 (R = Pri,Ph)

Cp(CO)₂Mn · THF reacts in THF with thiosters of phosphorus acid, P(SR)₃, to give new complexes Cp(CO)₂MnP(SR)₃ in which the manganese atom is coordinated to the phosphorus atom. The X-ray crystal structure of compounds with R = Prⁱ and Ph was established. The metal atom has a coordination enviroment of the three-legged piano stool type. The bond angles OC-Mn-CO and OC-Mn-P are 90.6–95.9(4)°. Bond distances are: Mn-P 2.188(2) and 2.171(2) E, P-S 2.097(3)-2.137(3) E.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1116–1119, June, 1994.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No.93-03-5830).     

Synthesis and reactivity of Ir(I) and Ir(III) complexes with MeNH2, Me2C=NR (R = H, Me), C,N-C6H4{C(Me)=N(Me)}-2, and N,N'-RN=C(Me)CH2C(Me2)NHR (R = H, Me) ligands

Complexes [Ir(Cp*)Cl(n)(NH2Me)(3-n)]X(m) (n = 2, m = 0 (1), n = 1, m = 1, X = Cl (2a), n = 0, m = 2, X = OTf (3)) are obtained by reacting [Ir(Cp*)Cl(mu-Cl)]2 with MeNH2 (1:2 or 1:8) or with [Ag(NH2Me)2]OTf (1:4), respectively. Complex 2b (n = 1, m = 1, X = ClO 4) is obtained from 2a and NaClO4 x H2O. The reaction of 3 with MeC(O)Ph at 80 degrees C gives [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(NH2Me)]OTf (4), which in turn reacts with RNC to give [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(CNR)]OTf (R = (t)Bu (5), Xy (6)). [Ir(mu-Cl)(COD)]2 reacts with [Ag{N(R)=CMe2}2]X (1:2) to give [Ir{N(R)=CMe2}2(COD)]X (R = H, X = ClO4 (7); R = Me, X = OTf (8)). Complexes [Ir(CO)2(NH=CMe2)2]ClO4 (9) and [IrCl{N(R)=CMe2}(COD)] (R = H (10), Me (11)) are obtained from the appropriate [Ir{N(R)=CMe2}2(COD)]X and CO or Me4NCl, respectively. [Ir(Cp*)Cl(mu-Cl)]2 reacts with [Au(NH=CMe2)(PPh3)]ClO4 (1:2) to give [Ir(Cp*)(mu-Cl)(NH=CMe2)]2(ClO4)2 (12) which in turn reacts with PPh 3 or Me4NCl (1:2) to give [Ir(Cp*)Cl(NH=CMe2)(PPh3)]ClO4 (13) or [Ir(Cp*)Cl2(NH=CMe2)] (14), respectively. Complex 14 hydrolyzes in a CH2Cl2/Et2O solution to give [Ir(Cp*)Cl2(NH3)] (15). The reaction of [Ir(Cp*)Cl(mu-Cl)]2 with [Ag(NH=CMe2)2]ClO4 (1:4) gives [Ir(Cp*)(NH=CMe2)3](ClO4)2 (16a), which reacts with PPNCl (PPN = Ph3=P=N=PPh3) under different reaction conditions to give [Ir(Cp*)(NH=CMe2)3]XY (X = Cl, Y = ClO4 (16b); X = Y = Cl (16c)). Equimolar amounts of 14 and 16a react to give [Ir(Cp*)Cl(NH=CMe2)2]ClO4 (17), which in turn reacts with PPNCl to give [Ir(Cp*)Cl(H-imam)]Cl (R-imam = N,N'-N(R)=C(Me)CH2C(Me)2NHR (18a)]. Complexes [Ir(Cp*)Cl(R-imam)]ClO4 (R = H (18b), Me (19)) are obtained from 18a and AgClO4 or by refluxing 2b in acetone for 7 h, respectively. They react with AgClO4 and the appropriate neutral ligand or with [Ag(NH=CMe2)2]ClO4 to give [Ir(Cp*)(R-imam)L](ClO4)2 (R = H, L = (t)BuNC (20), XyNC (21); R = Me, L = MeCN (22)) or [Ir(Cp*)(H-imam)(NH=CMe2)](ClO4)2 (23a), respectively. The later reacts with PPNCl to give [Ir(Cp*)(H-imam)(NH=CMe2)]Cl(ClO4) (23b). The reaction of 22 with XyNC gives [Ir(Cp*)(Me-imam)(CNXy)](ClO4)2 (24). The structures of complexes 15, 16c and 18b have been solved by X-ray diffraction methods.     

Zur Bildung cyclischer Silylphosphane Umsetzung von Li-Phosphiden mit R2SiCl2 (R = Me,Et, t-Bu)

Formation of Cyclic Silylphosphanes. Reaction of Li-Phosphides with R₂SiCl₂ (R? Me, Et, t-Bu) The reaction of Me₂SiCl₂ with Li-phosphides (mixture of LiPH₂, Li₂PH) leads to the formation of Me₂Si(PH₂)Cl 1 , Me₂Si(PH₂)₂ 2 , H₂P? SiMe₂? PH? SiMe₂Cl 3 , (H₂P? SiMe₂)₂PH 4 , (HP? SiMe₂)₃ 6 , 5 , 7 , 8 , 9 , 10 , 40 . Excess of phosphides in Et₂O – as well as excess of LiPH₂ – favourably forms 10 . Li₂PH (virtually free of Li₃P and LiPH₂) is obtained by reaction of LiPH₂ · DME with LiBu; Li₃P by reaction of PH₃ with LiBu in toluene. Isomerization by Li/H migration determines the course of reaction of the PH-bearing compounds with Li-phosphides. With Me₂SiCl₂ Li₃P mainly generates compound 10 . The reaction of the Li-phosphides with Et₂SiCl₂ mainly leads to (HP? SiEt₂)₃ 18 and (HP? SiEt₂)₂ 17 as well as to Et₂Si(PH₂)Cl 11 , Et₂Si(PH₂)₂ 12 , (ClEt₂Si)₂PH 13 , H₂P? SiEt₂? PH? SiEt₂Cl 14 , (H₂P? SiEt₂)₂PH 15 and 16 . In the reaction with LiPH₂ · DME the same compounds are obtained and isomerization by Li/H migration (formation of PH₃) already begins at ?70°C. In toluene ClEt₂Si? P(SiEt₂)₂P? SiEt₂Cl is additionally formed. Derivatives of 9, 10, 40 are not observed. The reaction of (t-Bu)₂SiCl₂ with LiPH₂ leads to HP[Si(t-Bu)₂]₂PH 20 (yield 76%) and formation of PH₃, the reaction with Li₂PH to 20 (54%) besides HP[Si(t-Bu)₂]₂PLi 21 .     

Raman spectra and molecular dynamics of R2NPX2 (R=Me and Et; X=F, Cl, and Br)

The Raman spectra of compounds R₂NPX₂ (R=Me and Et; X=F, Cl, and Br) were studied. The time correlation functions of vibrational and rotational relaxations as well as the characteristic times of these processes were calculated. Conclusions concerning the mechanisms of formation of the contours of the Raman lines with frequencies in the 670–705 cm⁻¹ range corresponding to the totally symmetric vibrations of the P-N bond in the R₂NPX₂ molecules were drawan. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 961–967, May 1997.     

Synthesis, characterization, and hydrolytic behavior of mixed-ligand diorganotin esters, [R2Sn(O2CR')OSO2Me]2 (R=n-Pr, n-Bu; R'=C9H6N-2, 4-OMe-C9H5N-2, C9H6N-1)

Reactions of the tin precursors, R2Sn(OMe)OSO2Me (R=n-Pr, n-Bu), with an equimolar quantity of 2-quinoline/4-methoxy-2-quinoline/1-isoquinoline carboxylic acid in acetonitrile proceed under mild conditions (rt,12-15 h) via selective Sn-OMe bond cleavage to afford the corresponding mixed-ligand diorganotin derivatives [R2Sn(O2CR')OSO2Me]2 [R'=C9H6N-2, R=n-Pr (1), n-Bu (2); R'=4-OMe-C9H5N-2, R=n-Pr (3), n-Bu (4); R'=C9H6N-1, R=n-Pr (5), n-Bu (6)]. These have been characterized by FAB mass, IR, and multinuclear (1H, 13C, 119Sn) NMR spectral data and X-ray crystallography (for 4 and 6). The molecular structure of 4 (C20H29NO6SSn, monoclinic, P2(1)/n, a=14.1(13) A, b=16.7(18) A, c=20.3(19) A, beta=107(4) degrees, Z=8) comprises distorted octahedral geometry around each tin atom by virtue of weakly bridging methanesulfonate [Sn(1A)-O(3B)=3.010, Sn(1B)-O(3A)=2.984 A] and (N,O) chelation of the carboxylate ligands. The spectral data of 1-4 suggest a similar structural motif in solution. The molecular structure of 6 (C38H53N2O10S2Sn2, monoclinic, P2(1)/c, a=11.339(2) A, b=14.806(3) A, c=24.929(5) A, beta=100.537(3) degrees, Z=4) reveals varying bonding preferences with monomeric units being held together by a bridging methanesulfonate [Sn(2)-O(5)=2.312(2) A] and a carboxylate group bonded to Sn(1) and Sn(2) atoms, respectively. Slow hydrolysis of compound 2 derived from 2-quinoline carboxylic acid in moist CH3CN affords the asymmetric distannoxane, [Bu2Sn(O2CC9H6N-2)-O-Sn(OSO2Me)Bu2]2 (7) (C27H45NO6SSn2, monoclinic, C2/c, a=21.152(3) A, b=13.307(2) A, c=26.060(4) A, beta=110.02(10) degrees, Z=8) featuring ladder type structural motif by virtue of unique mu2-coordination of covalently bonded oxygen atoms [O(6), O(6)#1] of the methanesulfonate groups.     

Nitrogenase model complexes [Cp*Fe(mu-SR(1))2(mu-eta(2)-R(2)N=NH)FeCp*] (R(1) = Me, Et; R(2) = Me, Ph; Cp* = eta(5)-C5Me5): synthesis, structure, and catalytic N-N bond cleavage of hydrazines on diiron centers

The reactions of [Cp*Fe(mu-SR1)3FeCp*] (Cp* = eta5-C5Me5; R1 = Et, Me) with 1.5 equiv R2NHNH2 (R2 = Ph, Me) give the mu-eta2-diazene diiron thiolate-bridged complexes [Cp*Fe(mu-SR1)2(mu-eta2-R2N NH)FeCp*], along with the formation of PhNH2 and NH3. These mu-eta2-diazene diiron thiolate-bridged complexes exhibit excellent catalytic N-N bond cleavage of hydrazines under ambient conditions.     

Synthesis,spectral and magnetic studies on mixed-ligand complexes M(DIAFO)2(NCS)2 and M(DIAFH)2X2 (M = FeII,CoII, NiII). The crystal structure of Co(DIAFO)2(NCS)2

Summary A series of mixed-ligand complexes of group VIII metals, M(DIAFO)₂(NCS)₂ and M(DIAFH)₂X₂ (M = Fe^II, Co^II, Ni^II, X = NCS^–, Cl^–) with the 3,3-bridged derivative of 2,2-bipyridyl (bipy) (1) were prepared, where DIAFO (2) and DIAFH (3) are 4,5-diazafluoren-9-one and 4,5-diazafluoren-9-hydrazone, respectively. These complexes were investigated by i.r., u.v.-vis-near i.r. spectroscopy and by variable-temperature magnetic susceptibility measurements. The electronic spectra show that the two ligands exert a field strength far removed from the Fe^II cross-over value. All the complexes are paramagnetic, following the Curie-Weiss law in the 77–300 K range. A typical crystal structure of Co(DIAFO)₂(NCS)₂ for these compounds was determined with orthorhombic, space group Pcan, a = 10.377(5) Å, b = 13.289(6) Å, c= 16.629(7) Å, V = 2293(2) ų, D _c = 1.563 g cm^–3, F(000) = 1091.74, Z = 4, R = 0.043, R = 0.047. Steric effects are thought to be operative in both ligands studied, but are weaker than those of the typical bidentate diimine ligand bipy.Author to whom all correspondence should be directed.     

Synthesis and characterization of diorganotin(IV) complexes of tetradentate Schiff bases: crystal structure of n-Bu2Sn(Vanophen)

Diorganotin(IV) complexes of the general formula R₂SnL (R=Ph, n-Bu and Me) have been prepared from diorganotin(IV) dichlorides (R₂SnCl₂) and tetradentate Schiff bases (H₂L) containing N₂O₂ donor atoms in the presence of triethylamine in benzene. The Schiff bases, H₂L, were derived from salicylaldehyde, 3-methoxysalicylaldehyde (o-vanillin), 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and diamines such as o-phenylenediamine and 1,3-propylenediamine. The complexes were characterized by IR, NMR (¹H, ¹³C, ¹¹⁹Sn) and elemental analysis. The structure of the complex, n-Bu₂Sn(Vanophen), was determined using single crystal X-ray diffraction. The tin atom has a distorted octahedral coordination, with the Vanophen ligand occupying the four equatorial positions and the n-butyl groups in the trans axial positions. Six-coordinated distorted octahedral structures have been proposed for all diorganotin(IV) complexes studied here, as they possess similar spectroscopic data.     

Synthesis and spectroscopic characterization of bis(N-alkyldithiocarbamato)nickel(II) complexes: crystal structures of [Ni(S2CNH(n-Pr))2] and [Ni(S2CNH(i-Pr))2]

Bis(N-alkyldithiocarbamato)nickel(II) complexes (1–5) [Ni(S₂CNHR)₂] (where R?=?Me, Et, n-Pr, i-Pr, n-Bu) were synthesized by the reaction of NiCl₂?·?6H₂O and the corresponding sodium salt of N-alkyldithiocarbamate in 1?:?2 molar ratio in aqueous medium. These bis(N-alkyldithiocarbamato)nickel(II) complexes (1–5) were characterized by elemental analysis, UV-Visible, IR, and ¹H/¹³C-NMR spectroscopy. The crystallographic investigation of [Ni(S₂CNH(n-Pr))₂] (3) and [Ni(S₂CNH(i-Pr))₂] (4) revealed distorted square-planar geometry around nickel(II). The dithiocarbamates have anisobidentate coordination with nickel and the dithiocarbamates are trans.