Volume 56, Issue 7

Radical Labeled M etallocenes (M = Fe, Co). M etallocenylene B ridged B is(3-im idazolin-l-oxyls) The addition of the lithium salt of the silyl protected hydroxylamine 1-hydroxy-2,2,4,5,5-pentamethyl-3-imidazoline (1) to 6 ,6 -dimethylfulvalene gives the lithium cyclopentadienide 2 from which the 1,1 '-substituted ferrocene and cobaltocinium derivatives 3 and 4 were obtained. Deprotection and oxidation of 3 and 4 afford the metallocenylene bridged bis(3-imidazolin-l-oxyls) 5 and 7. The ferrocene bridged diradical 5 forms with DDQ a charge transfer complex 8 . The complexes 5 and 7 were characterized by X-ray diffraction and by their EPR spectra. Magnetic measurements show at room temperature two independent spins for 5 and 7 and four unpaired electrons for 8 , the latter arising from three different sources [Fe(III) low spin d 5 , two nitroxides and DDQ - radical anion].

The structures, energies and vibrational frequencies of H 2 N-NO 2 and H 2 N-NO have been calculated at HF, MP2(FC), MP2(FULL) and CISD levels of theory using a polarized triple-zeta 6-311+G(d,p) basis augmented with a diffuse function. In addition, the structures and energies were also computed at the QCISD(T)/6-311+G(d,p) level of theory. The structure and bonding in H 2 N-NO 2 and H 2 N-NO is discussed on the basis of a Natural Bond Orbital Analysis (NBO analysis) and in addition based on qualitative valence bond (VB) considerations.

The metalation of triisopropylsilylphosphane with potassium bis(trimethylsilyl)amide yields quantitatively colorless pyrophoric potassium triisopropylsilylphosphanide (1 ) which is insoluble in hydrocarbons. The reaction of 1 with indium(III)chloride in toluene gives potassium tetrakis(triisopropylsilylphosphanyl)indate (2) in a rather poor yield. In the solid state this compound shows the formation of a one-dimensional polymeric chain with the indium as well as the potassium atoms in a distorted tetrahedral environment. The mean In-P and K-P bond lengths are 257.0 and 330.4 pm, respectively.

The reactions of [Fe('pyS 4 ')] 2 with PMe 3 , PnPr 3 , N 2 H 4 and pyridine afforded mononuclear [Fe(L)('pyS 4 ')] complexes with L = PMe 3 ( 1 ), PnPr 3 (2 ), N 2 H 4 (3) and pyridine (4). NMR spectroscopy, magnetic measurements and X-ray structure determinations revealed that all complexes exhibit frans-thiolate donors and low-spin Fe II centres, irrespective of the σ-π or σ ligand character of L. In this regard, the properties of [Fe(L)('pyS 4 ')] complexes strongly contrast with those of [Fe(L)('NHS 4 ')] complexes ('N H S 4 ' 2- = 2 ,2 '-bis(2 -mercaptophenylthio)- diethylamine(2 -)) and indicate that the rigid py(CH 2 ) 2 entity of the 'pyS 4 2- ligand is able to enforce trans configurations and low-spin states of complexes with [FeNS 4 ] cores. In spite of their diamagnetism, confirming the absence of antibonding electrons, all complexes 1 to 4 are highly reactive and rapidly exchange their L ligands for CO to give [Fe(CO)('pyS 4 ')]. Evidence was obtained that the oxidation of [Fe(N'-H 4 )('pyS 4 ')] (3) yields the diazene complex [μ-N 2 H 2 {Fe('pyS 4 ’)} 2 ] (5).

The stannides RERhSn (RE = Ho -Yb) and ScTSn (T = Pd, Pt) were prepared by reaction of the elements in sealed tantalum tubes in a high-frequency furnace, by arc-melting, or by a tin-flux technique in quartz tubes. The rhodium based stannides crystallize with the ZrNiAl type structure, space group P6̄2m. The four structures were refined from single crystal X-ray data: a = 754.5(3), c = 377.1(1) pm, wR2 = 0.0357, 233 F 2 values for HoRhSn, a = 753.3(1), c = 372.16(8) pm, wR2 = 0.0721, 233 F 2 values for ErRhSn, a = 753.7(3), c = 369.0(2) pm, wR2 = 0.0671,233 F 2 values for TmRhSn, and a = 753.17(5), c = 366.53(4) pm, wR2 = 0.0566, 180 F 2 values for YbRhSn with 14 parameters for each refinement. ScPdSn and ScPtSn adopt the HfRhSn type, a superstructure of ZrNiAl, space group P6̄2c: a = 747.5(1), c = 710.2(1) pm, for ScPdSn, and a = 738.37(9), c = 729.47(9) pm, wR2 = 0.0452,369 F 2 values, 18 variables for ScPtSn. Structural motifs in these stannides are transition metal centered trigonal prisms formed by the rare earth and tin atoms. While these prisms are regular in the rhodium based stannides, significant distortions occur in ScPdSn and ScPtSn. The formation of the superstructure can be ascribed to packing reasons. The shortest interatomic distances occur between the transition metal (T) and tin atoms. These atoms form three-dimensional [FSn] networks in which the rare earth atoms fill distorted hexagonal channels. The series RERhSn displays a somewhat unique behavior. The a lattice parameter is more or less independent of the rare earth element, while the c lattice parameter shows the expected lanthanoid contraction. 119 Sn Mössbauer spectroscopic data of the rhodium stannides show signals at isomer shifts varying from 1.77 to 1.82 mm/s subject to quadrupole splitting between 0.75 to 0.82 mm/s.

New intermetallic compounds EuAgCd and YbAgCd were synthesized in quantitative yield by reaction of the elements in sealed tantalum tubes in a high-frequency furnace. Both com­ pounds were investigated by X-ray diffraction on powders and single crystals: KHg 2 type, Imma, a = 490.41(8), b = 771.0(1), c = 834.4(2) pm, wR2 = 0.0624, 255 F 2 values, 12 variables for EuAgCd, and MgZn 2 type, Pb 3 /mmc, a = 584.66(5), c = 946.83(9) pm, wR2 = 0.0502, 187 F 2 values, 11 variables for YbAgCd. Owing to the very small difference in scattering power, no long range ordering of the silver and cadmium atoms is evident from the X-ray data, although Ag-Cd ordering is expected. The silver and cadmium atoms randomly occupy the mercury and zinc positions of the KHg 2 and MgZn 2 type structures, respectively. In EuAgCd the [AgCd] substructure consists of strongly puckered, orthorhombically distorted Ag 3 Cd 3 hexagons, while a three-dimensional network of face-and comer-sharing tetrahedra is observed in YbAgCd. The rare earth atoms fill the space between the Ag 3 Cd 3 hexagons (EuAgCd) or within the three-dimensional tetrahedral network (YbAgCd). Magnetic susceptibility measurements in­ dicate Pauli paramagnetism for YbAgCd and Curie-Weiss behavior above 60 K for EuAgCd with an experimental magnetic moment of 7.82(3) μ B /Eu indicating divalent ytterbium and europium. Ferromagnetic ordering at Tc = 28.0(5) K is observed for EuAgCd. At 2 K and 5 T the saturation magnetization is 5.85(5) μ B /Eu.

Ba 16 NbsN 19 was synthesized by reaction of Ba with Nb under nitrogen at ambient pressure at 1223 K. The refined crystal structure was solved in the space group P1̄ (no. 2), Z = 2, with the lattice constants a = 1099.33(3), b = 1140.41(15), c = 1622.06(6) pm, α = 72.197(2)°, β = 59.949(1)°, γ = 82.243(2)° and R 1 = 0.058, wR 2 = 0.088. The crystal structure contains both isolated [NbN 4 ] 7- as well as dimeric units [Nb 2 N 7 ] 11- . Together with the Ba 2+ ions the compound has to be regarded as Ba 16 [NbN 4 ] 3 [Nb 2 N 7 ].

The new compounds Ni 2 (tren) 3 (M O₂ O 2 S 6 ) 2 · 2.75 H 2 O (I) and C O₂ (tren) 3 (MoS 4 ) 2 (II) (tren = tris(2-aminoethyl)amine) were prepared under solvothermal conditions. The structure of I is built up of one-dimensional [Ni 2 (tren) 3 ] n 4+ chains and isolated [M O₂ O 2 S 6 ] 2- anions. Each Ni atom in the cationic chain is surrounded by six N-atoms to form a distorted octahedron. The connection of the Ni-atoms in the [Ni 2 (tren) 3 ] n 4+ -units with the tren molecules leads to zigzag chains in the (100) plane. The situation is different for compound II which consists of isolated [C O₂ (tren) 3 ] 4+ cations and discrete tetrahedral [M O S 4 ] 2- anions. The Co atom in the cation is in a distorted trigonal bipyramidal environment of four N atoms of one tren molecule and of one N atom from a bridging tren-molecule, building up the dimeric structure of the [C O₂ (tren) 3 ] 4+ unit. Between the anions and cations of both compounds hydrogen bonding is observed. The thermal behaviour of I and II was investigated using differential thermoanalysis and thermogravimetry. On heating I first looses the crystal water and then decomposes slowly in one step, whereas II decomposes also in one step, but at a significantly lower temperature.

LaAlSi 2 (a = 4.196(2), c = 11.437(7) Å; P3̄ml; Z = 2) was synthesized by arc-melting of preheated mixtures of the elements. The compound was investigated by means of X-ray methods and by neutron diffraction. The crystal structure can be described as a stacking variant of two different segments. The first one corresponds to the CaAl 2 Si 2 structure type (LaAl 2 Si 2 ), the second one with the A1B 2 structure type (LaSi 2 ). The segments are stacked along [001]. The electronic structure of the compound is discussed on the basis of LMTO band structure calculations.

Die Kristall­ struktur von [CollH] 2 [AsF 6 ][As 2 F 11 ] (Coll = 2,4,6-Trimethylpyridin) Collidinium and Imidazolium Salts of Fluorine-Containing Anions. The Crystal Structure of [CollH] 2 [AsF 6 ][As 2 F 11 ] (Coll = 2,4,6-Trimethylpyridine) From s-Collidine (1, Coll) and aqueous HF compounds of the composition Coll · n HF (n = 1 -2) are formed which are transformed to [CollH] + [HF 2 ] - (2) by sublimation. [CollH] 2 [AsF 6 ][As 2 F] J (3) is obtained from 1 and the superacid system HF/AsF5. 2 reacts with 2,3-dihydro-l,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (4, Im) to give the imidazo­ lium salt [ImH] + [HF 2 ] - (5). Hydrogen bonds in the crystal structure of [CollH] 2 [AsF 6 ][As 2 Fn ] (3) are discussed.

The compound (Me 2 NO) 3 SiOSi(ONMe 2 ) 3 was prepared by the reaction of LiONMe 2 with Si 2 Cl 6 , a reaction in which oxygen is inserted into the Si-Si bond. The crystal structure of (Me 2 NO) 3 SiOSi(ONMe 2 ) 3 was determined and shows the compound to have a linear siloxane core and SiON units with small valence angles at oxygen, caused by weak Si (-N interactions leading to partially hypercoordinate Si centres.

Water- and oxygen-sensitive compounds R*EHal 2 •D, R*EHal 2 and R* 2 EHal (R* = SitBu 3 ; E = B, Al, Ga, In, TI; Hal = F, Cl, Br, I; D = OR 2 , NR 3 ) have been synthesized by reaction of EHal 3 with NaR* in the absence or presence of donors as well as by substitution of D, Hal or R* by other substituents, or by reaction of R* 2 E-ER* 2 (E = Al, In) with I 2 , H 2 , AgF 2 or HBr. Thermal decomposition of the compounds in solution or in the gas phase leads to elimination of D from R*EHal 2 •D, or of R*Hal from R*EHal 2 and R* 2 EHal, respectively. The dihalides R*EHal 2 act as Lewis acids with respect to donors OR 2 or NR 3 (formation of adducts R*EHal 2 •D), the monohalides R* 2 EHal as Lewis bases with respect to acceptors EHal 3 (formation of R* 2 E + EHal 4 - ). Dehalogenations of R* 2 EHal and R*EHal 2 with alkali metals or NaR* leads to compounds R* 4 E 2 (E = AI, In, Tl), R* 3 E 2 • (E = AI, Ga), R* 4 E 3 • (E = Al, Ga), R* 4 E 4 (E = AI, Ga), R* 6 Ga 8 , R* 8 In 12 , (R* 2 B - ), R* 2 A - , R* 3 Ga 2 - , R* 4 Ga 3 - , R* 4 Ga 4 2- , R* 4 Tl 3 Cl, or R* 6 Tl 6 Cl 2 . The structures of R*BBr 2 •Py, R*AlBr 2 •NEtMe 2 , (R*AlClOBu) 2 , R* 2 BF as well as R* 2 ECl (E = B, Al, Ga, Tl) have been determined by X-ray structure analyses.

Water- and oxygen-sensitive compounds of the type R ’ n EHal 3-n (R' = SitBu 2 Ph; E = Triel) with or without donors, viz. RAlBr 2 , R' 3 Al, R'GaCl 2 'THF, R'GaCl 2 , R' 3 Ga, R'InCl 2 ·THF and R' 3 In have been synthesized by reaction of EX 3 with NaSitBu 2 Ph (prepared for this purpose) in the absence or presence of donors. The dihalides R'EHal 2 have also been obtained by reaction of R' 3 E with EHal 3 , whereas monohalides R' 2 EHal are not accessible via these and other routes up to date. All trielanes have been characterized by NMR and the structures of the R' 3 E compounds have been determined by X-ray analyses.

The aminoiminoborane tmp-B=NCMe 3 (1) adds to TiBr 4 or ZrCl 4 in a 1:1 ratio while PdCl 2 adds 1 in a 1:2 ratio. In these new compounds the NBN unit is almost linear and the configuration corresponds to an allene. On the other hand 1 and Ti(OR) 4 compounds and Ti(NMe 2 ) 4 give N metallated diaminoboranes tmp-B(X)-NCMe 3 EX 3 (X = OR, NMe 2 ). Mixed compounds Ti(OR) 3-n X n lead to diaminoboranes with BOR groups while the TiCl bond inserts into the B = N bond of 1 to produce tmp-BNMe 2 -NCMe 3 TiCl 3 . Hydrolysis of this compound leads to a spirocyclic dititanoxane with a short linear Ti-O-Ti bond and pentacoordinated Ti centers carrying two Cl atoms each. Spirocycles with a BN 2 E (E = Ti, Nb, Ta, Pd) unit are formed when 1 is allowed to react with TiCl 4 , NbCl 5 , TaCl 5 and PdCl 2 . The palladium compound 16 is dimeric, and dimerization occurs via Pd-Cl bridges. The aminoiminoborane tmp-B=NC 6 H 3 -2,6-iPr 2 reacts with the titanium compounds in the same manner as 1, however without formation of spirocycles.

The reaction of Ph 2 SbSiMe 3 with CpFe(CO) 2 X (X = Cl, Br) leads to the formation of the diphenyldiferriostibonium salts [{CpFe(CO) 2 } 2 SbPh 2 ] 2 FeX 4 , whereas PhSb(SiMe 3 ) 2 and CpFe(CO) 2 Cl react to give the phenyltriferriostibonium salt [{CpFe(CO) 2 } 3 Sb] 2 FeCl 4 . Sb(SiMe 3 ) 3 reacts with CpFe(CO) 2 X (X = Cl, Br) to yield the halogenotriferriostibonium salts [{CpFe(CO) 2 } 3 SbX] 2 FeX 4 . The chloro derivative can also be obtained: from SbCl 3 with {CpFe(CO) 2 } 2 or Na[CpFe(CO) 2 ], and from SbCl 5 and Na[CpFe(CO) 2 ], The compounds have been characterized by spectroscopic (IR, NMR, MS), analytical (C, H) and X-ray diffraction investigations ([{CpFe(CO) 2 } 2 SbPh 2 ] 2 FeBr 4 , [{CpFe(CO) 2 } 3 SbPh] 2 FeCl 4 , [{CpFe(CO) 2 } 3 SbCl] 2 FeCl 4 ).

Eight compounds of the type (RSO 2 ) 2 N-C(O)-NR' 2 , where R = Me or 4-tolyl and R' = Me, Et, i Pr or Ph, were obtained in good yields by treating the corresponding carbamoyl chlorides R' 2 NC(0)C1 with silver salts AgN (SO 2 R) 2 in acetonitrile solution. The pronounced sensitivity of the compounds towards atmospheric moisture is indicative of a high degree of electrophilic activation at the carbonyl centre; bulk hydrolysis rapidly leads to carbon dioxide and the corresponding ammonium salt R' 2 NH + 2 'N (SO 2 R) 2 . In the 1 H and 13 C NMR solution spectra, the R4N groups of the ureas give rise to distinct R' resonances at room temperature, reflecting unusually high barriers to rotation about the C(O)-NR' 2 bonds. For ( MeSO 2 ) 2 N-C(O)-NMe 2 (1a) and the analogous ditosyl compound, the 1 H NMR signals of the dimethylamino group were found to coalesce at 107 °C and 93 °C, respectively, which corresponds to a rotational barrier of ⊿G # c ≈ 80 kJ mol -1 . In the crystal of la (triclinic, space group P1̄, Z = 2; X-ray diffraction at -75 °C), the molecule possesses an essentially planar Me 2 N-C(O)-N moiety (except H atoms), whereas the C-NS 2 grouping is pyramidalized to such an extent that N lies 27.8(2) pm out of the plane defined by the carbonyl C atom and the two sulfonyl S atoms [S-N-S 120.52(11)°, C-N-S 115.73(14) and 115.06(14)°]. The most remarkable features of the molecular structure are the exceedingly long C(O)-NS 2 bond [148.6(3) pm] and the concomitantly short C-O and C(O)-NC 2 bonds [121.4(3) and 132.2(3) pm]. The crystal packing of la is governed by a three-dimensional network of nine intermolecular C-H···O hydrogen bonds originating from the activated M e-S and M e -N donor groups (H···O 230-266 pm, C-H···O 123-173°).

Isochrysophanol, isozyganein, ω-hydroxyisochrysophanol, and morindaparvin are naturally occurring substituted anthraquinones. We report the synthesis of these compounds as well as selected biological activities.