Volume 44, Issue 4

The first bis(cyclotriphosphanyl)diorganylcyclotetraphosphane [(t-BuP) 2 P] 2 (t-Bu) 2 P 4 (1) has been obtained by reacting (t-BuP) 2 PSnMe 3 with PCl 3 , in the molar ratio 3:1. and has been isolated in pure form. Compound 1 is formed as a mixture of two configurational isomers 1a and 1b, which differ in the relative arrangement of the trans-oriented tert-butyl groups at the two three-membered rings. The constitutional isomer, in which three atom , is obviously not stable for steric reasons.

Sodium pentaphosphacyclopentadienide has been prepared as a pure NaP 5 /[18]crown-6/THFsolution by reacting white phosphorus with sodiumdihydrogenphosphide (P :NaPH 2 = 5:1 to 5.6:1) in boiling tetrahydrofuran in the presence of [18]crown-6.

From aqueous HF solutions the following fluorooxo complexes have been crystallized and characterized: A I (NMe 4 ) 2 [V 3 O 3 F 12 ] (1), A I = Na. K; K 2 (NMe 4 )[V 2 O 2 F 9 ]·H 2 O (2); Cs(NMe 4 )[V 2 O 2 F 8 (H 2 O)] (3) and NMe 4 [VOF 4 ] (4). The structures of 1 and 3 have been determined. Crystal data: 1c, hexagonal, space group P6 3 /m . a = 1695.0(9), c = 1248.1(5) pm. Z = 6: 1803 reflections. R = 0.045. 3, orthorhombic. space group Pnma, a = 2152.8(7), b = 751.5(2), c = 850.7(2) pm, Z = 4; 1379 reflections, R = 0.030. 1 contains a trimeric, cyclic anion with asymmetrically bonded μ-fluoroligands and terminal V = O groups in the same plane; the anion of 3 is a fluorobridged dimer with unequally coordinated vanadium atoms with terminal V = O groups. The preparation of these com pounds establishes the presence of VOF 4 (H 2 O) - species in aqueous solutions.

From aqueous HF solutions the following fluorooxo complexes have been obtained: K 2 (NMe 4 )[Mo 2 O 2 F 9 ]·H 2 O (1), K(NMe 4 ) 2 [Mo 3 O 6 F 9 ] (2), (NMe 4 ) 2 [Mo 2 O 4 F 6 (H 2 O)] (3), (NMe 4 ) 2 [W 2 O 4 F 6 (H 2 O)] (4) and (NEt 4 ) 2 [Mo 2 O 4 F 6 ] (5). The structures of 1 and 3 have been fully determined: Crystal data, 1, orthorhombic, space group Abm 2, a = 632.4(2), b = 2078.8(6), c = 1252.3(4) pm, Z = 4; 949 reflections, R = 0.0203. 3, orthorhombic, space group Pca 2 1 , a = 1086.1(2), b = 1386.1(2), c = 1194.4(2) pm, Z = 4; 1826 reflections, R = 0.0231. 1 and 3 contain dimeric fluoro-bridged anions. The central atoms of 3 (and of the isostructural 4) are unequally coordinated. The anion of 2 is a cyclic fluoro-bridged trimer with cis-dioxo groups in the molecular plane. In the anion of 5 two octahedra share an edge, occupied by fluoro ligands.

Compounds of the general formula (CMe 3 ) 2 Si(R)OH, (R = Cl, OH, NH 2 ) react with n-C 4 H 9 Li or Na to give the alkali silanolates 1-5.1-5 serve as starting materials in the reactions with chlorosilanes for the synthesis of siloxanes (6-12). Ring closure reactions of dilithiated 9,11, and 12 occur with SiCl 4 (13) and Cl 2 SiMe 2 (15, 16). 13 contains an (SiO ) 4 , 15 an Si(OSiN) 2 Si. and 16 an O(SiOSi) 2 N eight-membered ring. Hydrolysis of 13 leads to the formation of the hydroxy-substituted eightmembered ring 14. The crystal structures of (CMe 3 ) 2 Si(OH)-O-SiMe,-O-(H 2 N)Si(CMe 3 ), (11) and Me 2 Si[OSi(CMe 3 ) 2 NH] 2 SiMe 2 (15) are reported and discussed.

Simultaneous strontium and zinc substitution for calcium in the fluoroapatite lattice was investigated. Crystallographic data for different members of the series Cain 10-x-y Sr x Zn y (PO 4 ) 6 F 2 were obtained from X-ray powder diagrams. The effects of the substitutional process on the strength of the phosphate P -O-bonds were checked by Raman spectroscopy. For comparative purposes, the first members of the series Sr 10-x Z x (PO 4 ) 6 F 2 were also investigated in a similar way.

The bromoarsenates(lll) [Et 4 N] 3 [As 3 Br 12 ] (1). [Ph 4 P] 2 [As 2 Br 8 ] (2), [(n-prop) 4 N] 2 [As 2 Br 8 ] (3) and {[pipH] 3 [As 2 Br 9 ] · [pipH]Br} (4) have been prepared and their structures established by X-ray structural analysis. The central As atom in the novel face-bridged trioctahedral species [As 3 Br 12 ] displays an effectively regular octahedral coordination in one of the two independent anions in the unit cell of 1. The As-Br distances are 2.671 (1) - 2.672(2) Å with Br-A s-Br angles in the range 88.8(1)-91.2(1)°. In contrast the outer As atoms exhibit a severely distorted octahedral geometry with three short As - Br terminal bonds (2.404(2)-2.409(2) Å). The [As 2 Br 8 ] 2- anions in 2 and 3 are centrosymmetric with the As atoms displaying a square-pyramidal coordination. A structural correlation of opposite As-Br distances in the linear three-centre Br-As···Br interactions is presented. The sum of the bond valences in bromoarsenates(III) is a minimum for the regular octahedral geometry, reflecting, thereby, the influence of the As 4s-orbital in the antibonding 2a 1g MO. An empirical expression for As-Br distances in bromoarsenates(III) is derived.

The reaction of [PtCI 6 ] 2- with BrF 3 generates the mixed complexes [PtF n C 6-n ] 2- , n = 1- 5, of which the species with n = 2. 3, 4 are cis-configurated. Due to the stronger trans-effect of Cl compared to F, on treatment of [PtF 5 Cl] 2- and cis-[PtF 4 Cl 2 ] 2- with Cl - the trans-isomers are formed stereospecifically. The pure fluoro-chloro-platinates(IV) are separated by ion exchange chromatography on diethylaminoethyl-cellulose. The vibrational spectra o f the mixed ligand complexes are completely assigned according to point groups D 4h , C 4v , C 3v and C 2v . The Pt-Cl stretching vibrations of [PtF 5 Cl] 2- , trans-[PtF 4 Cl 2 ] 2- , mer-[PtF 3 Cl 3 ] 2- and [PtFCl 5 ] 2- are split by the isotopes 35 Cl and 37 Cl, showing well resolved sharp Raman lines in the expected ratio of intensities.

. Triphenylboron adducts of 2- and 3-hydroxyalkyl isocyanides spontaneously undergo intramolecular cyclization to give oxazolidin-2-ylidene and perhydrooxazin-2-ylidene boron complexes, respectively. The same compounds are obtained by methanolysis of the stable species Ph 3 B-CNCR 1 R 2 CR 3 R 4 -OSiMe 3 (R 1 , R 2 , R 3 , R 4 = H, alkyl) (2a-i) and Ph 3 B-CN(CH 2 ) 3 -OSiMe 3 (2j)IR, 1 H NMR, 13 C{H} NMR. and mass spectra of the new compounds are reported.

Reactions of the low valent azido complex NEt 4 [CpMn(CO) 2 N 3 ] (1) with electrophiles preferably give the dinitrogen complex [CpMn(CO) 2 N 2 ] (2). Thus, 2 forms when 1 is reacted with NOBF 4 , NO 2 BF 4 or HCl/THF. respectively. 2 forms also if 1 is reacted with the 1,3-dipolarophile CI 3 C-CN. The reaction of 1 with CH 3 I. however, gives the methylamine complex [CpMn(CO) 2 NH 2 CH 3 ], presumably via methylazido, -nitrene and -aminyl interm ediates. Cycloadditions could be achieved with the isoelectronic [CpFe(cdpe)N 3 ] (3); 3 yields the corresponding 2-triazolato-4,5-dialkylester complexes 4 when reacted with RO 2 C-C=C-CO 2 R(4a: R = Me; 4b: R = Et). The ethyl derivative was characterized by X-ray structure analysis.

The (ether-phosphane) complexes cis-Cl 2 Pt(Ph 2 P∼D ) 2 (2a, b) [D = CH 2 C 4 H 7 O (a). C H 2 C 4 H 7 O 2 (b)] are obtained by reaction of Ph 2 P∼D (1a , b) with either K 2 PtCl 4 or Cl 2 Pt(COD) (COD = 1,5-cyclooctadiene). Both Cl - anions are abstracted from 2a, b using AgSbF 6 to give the cationic bischelate complexes (5a, b). The stepwise cleavage and reform ation of Pt-O bonds in (ether-phosphane) platinum complexes is demonstrated bv the sequence (6a) → [trans-(Ph 2 P∼D ) 2 PtCO(Cl)][SbF 6 ] (7 a )→5a, when 5a, 6a, and 7a are reacted with KCl, CO, and AgSbF 6 respectively. Reduction of 2a with NaBH 4 results in the formation of trans-H 2 Pt(Ph 2 P∼D) 2 (4a). In the presence of HCl 2a is reformed. Excess NaBH 4 or heating of 4a yields the bischelate platinum(0) complex (3a), which is also isolated by reduction of 2a with sodium amalgam. A general method for obtaining (3a-c) [D = CH 2 CH 2 O CH , (c)] is the substitution of COD in Pt(COD) 2 by the ether-phosphanes 1a-c. The structures and bonding properties of the compounds 2-7 are discussed on the basis of their 31 P{ 1 H } NMR and IR spectra.

[Li 3 (12-crown- 4 ) 3 O 2 CCH 3 ][Cd(Se 4 ) 2 ] has been prepared by the reaction of [Li(12-crown-4)] 2 Se 6 with Cd(C 2 CCH 3 ) 2 in ethanolic solution. The corresponding polyselenide complex of mercury is formed by the reaction of [K(18-crown-6)] 2 Se 6 with Hg(O 2 CCH 3 ) 2 in the same solvent. Both com pounds form dark red crystals, which were characterized by single crystal X-ray structure determinations. The only product to be isolated from the reaction of Bi(NO 3 ) 3 ·5H 2 O with [Na( 15-crown-5)] 2 Se 6 in ethanolic solution was [Na(15-crown-5)]NO 3 , whose structure has also been determined. [Li 3 (12-crown-4) 3 O 2 CCH 3 ][Cd(Se 4 ) 2 ]: space group Pbca, Z = 8. 1404 observed independent reflexions. R = 0.097. Lattice dimensions (19 °C): a = 1981.5(6). b = 1400.3( 1), c = 3268.9(9) pm. The compound forms a dicationic ensemble, in which three lithium ions coordinate with the oxygen atoms of the acetate ion. In the anions the cadmium atom is coordinated tetrahedrally by four selenium atoms of two Se 4 2- units. {[K (18-crown-6)] 2 [Hg(Se 4 ) 2 ]} 2 : space group P 1, Z = 1. 3210 observed independent reflexions, r = 0.055. Lattice dimensions (19 °C): a = 1057.4(2). b = 1130.6(2), c = 2000.1(2) pm. α = 88.52(1)°, β = 85.86(1)°, γ = 66.22(1)°. The com pound has a complex ionic structure, in which the formula units form centrosymmetric dimers through K-O contacts between two cations. In addition there are K···Se contacts with the spiro-bicyclic anions, which - together with 6 K-O bonds within the crowns - lead to the coordination number of 8 for the remaining potassium ions. [Na(15-crown-5)]NO 3 : space group P2 1 2 1 2 1, Z = 4. 1211 observed independent reflexions. R = 0.052. Lattice dimensions (20 °C): a = 912.9(2). b = 989.6(1). c = 1658.3(3) pm. The compound forms ion pairs, in which the sodium atom coordinates with the five oxygen atoms oi the crown ether, as well as with two oxygen atoms of the nitrate ion with Na -O bond lengths of 240 and 247 pm.

Acetylenes carrying one bulky substituent can be transformed into symmetrically or asymmetrically substituted cyclopentadienones 2 or 3 when they are heated with Co 2 (CO) 8 and carbon monoxide. Intramolecular cyclizations yielding compounds 5 are also possible.

Various N-glycosides derived from glucose and α-amino acids and the isomeric Amadori compounds form bis(chelate) complexes of copper(II), palladium (II) and platinum (II). The IR spectra indicate that the ligands are coordinated through the amino group and a carboxylate oxygen atom.

N, N, N′, N′ -Tetramesyl dicarboxylic diamides Ms 2 NC(O)-Q-C(O)NMs 2 [Q = (CH 2 ) n with n = 0 (2a), 2 (2b), 3 (2c), 4 (2d); Q = o-phenylene (2e)] were prepared by reacting AgNMs 2 (1) with the appropriate dicarboxylic dichlorides in acetonitrile at room temperature (2a, 2 c-2e) or at 0 °C (2b), respectively. Under similar conditions, malonic dichloride undergoes an elimination, forming AgCl, HNMs 2 and probably polymeric C 3 O 2 . At 20 °C in CH 3 CN, the succinic acid derivative 2b eliminates one mole of HNMs 2 and, by ring closure, yields γ-dimesylamino-Δ βγ - butenolide (4a), the first example of a stable γ-amino-Δ βγ -butenolide. Treatment of 4a with aqueous NaOH results in the formation of NaNMs 2 and sodium succinate. Crystalline 4a is thermally stable at 100 °C; no signs of an isomerization 4a → γ-dimesylamino-Δ αγ -butenolide could be detected. Unlike the structurally related α-angelicalactone (4c), whose bromination affords the saturated dibromolactone 9 as a mixture of cis- and mws-isom ers, 4a adds bromine (20 °C, CHCl 3 ) under ring cleavage to form BrC(O)CH 2 CHBrC(O)NMs 2 (7). The new compounds 2, 4a and 7 as well as the stereoisomers of 9 were characterized by spectroscopic ( 1 H and 13 C NMR, MS, IR) and analytical methods. In order to obtain reference values for the chemical shifts of 7, the following new compounds were prepared: CH 3 (CH 2 ) 2 C(O)NMs 2 (10c, from 1 and butvryl chloride); CH 3 CH 2 CHBrC(O)NMs 2 (12c, from 1 and 2-bromobutyryl bromide); C 2 H 5 OC(O)CH 2 CHBrC(O)NMs 2 (13, from 7 with ethanol and from 4a by simultaneous reaction with bromine and ethanol).

The preparation and structure elucidation of Co(III)- and Ni(II)-complexes of pyridine- 2, 6-di(monothiocarboxylic acid) are reported. The Co ion chelates two of these tridentate ligands to form the octahedral bis(pyridine-2,6-dicarbothioato)-cobaltat(III). whereas the Ni ion coordinates only with two of the three binding sites of each ligand to give a tetrahedral complex. Bis(pyridine-2,6-dicarbothioato)-nickelat(II) is stable only in the absence of O 2 ; it polymerizes by formation of disulfid bridges between the free thiocarboxyl groups if exposed to air.

The reaction of 1 with N, N′-dimethyl-N, N′-bis(trimethyIsilyl)urea, 2 has furnished the compound Me 2 NCH 2 CH 2 N(Me)P(NMe) 2 C(:O), 3. Following oxidation o f phosphorus in 3 through several reagents, intramolecular donor-acceptor interactions were observed when an electronegative group was bonded to phosphorus; this group, activating the phosphorus atom, should be well polarizable in solution and should readily depart from the molecule as an anion. The unusual spirophosphoranes 8, 11 and 12 could thus be synthesized. The reaction of equimolar quantities of MeOCH 2 CH 2 OPCl 2 , 15 with 2 has furnished 16 which is related to 3. Reaction of 15 with excess 2 constitutes a new mode o f formation of the previously reported diphosphorus compound 17.

Some differently substituted 4-phenylthiophene derivatives 2a-d and 8a, b have been prepared from α-substituted-β-thiocyanatomethyl cinnamonitrile (1). The thiophene derivatives 2a, b and 8a react with trichloroacetonitrile and formamide to afford thieno[2,3-d]pyrimidine derivatives 4, 5 a-c, 7 and 9 a-c, respectively.

[MoCl 4 (NCl)] 2 has been prepared by the reaction o f molybdenum hexacarbonyl with excess nitrogen trichloride in CCl 4 solution; the product is a red, moisture-sensitive crystal powder. Decomposition above 100 °C leads to MoNCl 3 . According to the IR spectrum, [MoCl 4 (NCl)] 2 is dimerized via chloro bridges, the group being linear.

The title compound has been prepared by the reaction of FeCl 3 with N, N, N′-tris(trimethylsilyl) benzamidine in CH 2 Cl 2 solution as dark red, moisture-sensitive crystals. The complex was characterized by its IR spectrum as well as by an X-ray structure determination. Crystal data: space group P2 1 /n, Z = 2 (1178 observed independent reflexions, R = 0.089). Lattice dimensions (20 °C): a = 1240.2(2), b = 645.7(3), c = 1779.7(3) pm, β = 91.31(2)°. The compound forms centrosymmetric molecules, in which the iron atoms are members of two fused planar heterocycles with the NN group as the com m on edge. The NN bond length (142.5(9) pm) is very close to the NN bond length of hydrazine.

A quenchable high-pressure phase of AgNb 3 O8(AgNb 3 O8-II) could be synthesized at 35 kbar. 1100 °C in a modified Belt-type apparatus. The structure (Ibam, a = 7.343, b = 10.415. c = 7.007 Å , Z - 4) comprises dodecahedra NbO 7 and distorted pentagonal bipyramids NbO 7 shared in such a way that elongated hexagonal tunnels along [001] are formed. Ag + -ions are situated within these tunnels. The shortest O-O distances are 2.247(11) Å (shared edges between NbO 8 dodecahedra). AgNb 3 O 8 -II is metastable at atmospheric pressure and retransforms to the normal pressure phase AgNb 3 O 8 -I at 800 °C.

Some unsymmetrical chlorophosphines RR′PCI were prepared by the reaction of RPCl 2 (R = CH 3 , C 2 H 5 , i-C 3 H 7 , C 6 H 5 ) with Grignard reagents R′MgCl (R′ = c-C 5 H 9 , c-C 6 H 11 , i-C 3 H 7 ) and characterized by elemental analyses and spectroscopic data (IR, 31 P and 13 C NMR).