G. W. A. Fowles

Some coordination compounds of zirconium tetrabenzyl and some reactions in which there is insertion into carbonzirconium bonds

Abstract Zirconium tetrabenzyl (ZrBz 4 ) has been allowed to react with a number of nitrogen and oxygen donor ligands. Air-sensitive complexes of formula ZrBz 4 ·2L ZrBz 4 ·L or 2ZrBz 4 ·L have been isolated and characterised by analysis and by NMR and IR spectroscopy. The reaction of ZrBz 4 with SO 2 , PhNCO and MeNCS gave ZrBz(SO 2 Bz) 3 , Zr[NPhC(O)Bz] 4 and Zr(NMeC(S)Bz) 4 respectively.

The cleavage of an ether by reaction with tungsten(VI) selenide tetrachloride

The reaction of WSeCl4 with 1,2-dimethoxyethane (dme) results in the cleavage of one of the ether linkages and the formation of a tungsten alkoxide, the ethereal oxygen being co-ordinated to the tungsten atom. The crystal structure shows the WSe bond length to be 2.225(5) A, indicative of a multiple bond.

Reaction of some aliphatic and aromatic nitriles with tungsten(VI) chloride leading to the formation of tungsten–nitrogen multiply bonded compounds

From the reaction of WCl6 with a number of aliphatic and aromatic nitriles, compounds [WCl4(NCRCl2)]·RCN (R = Me, CH2Cl, CHCl2, CH2ClCCl2, CH2CH, CMe3, Ph, C6H4Cl-4, C6H4Me-2, or C6H4Me-4) have been isolated. These species have been characterised by analysis and n.m.r. and i.r. spectroscopy. It is suggested that these metal imido-derivatives may be intermediates in the formation of WCl4·2RCN from the reaction of WCl6 with alkyl cyanides.

Some coordination compounds of phenylzirconium trichloride

Abstract Phenylzirconium trichloride has been isolated as its tetrahydrofuran adduct PhZrCl 3 ·3thf (I). The reaction of I with a range of nitrogen, phophorus and sulphur ligands gave products of stoichiometry PhZrCl 3 ·thf·L (L = 2,2′-bipyridyl, 4,4′-bipyridyl, 2-methylpyridine or triphenylphosphine) and PhZrCl 3 ·thf·2L′ (L′ = pyridine, PhCN or 1,4-thioxan). Reaction of I with methyl cyanide gave PhZrCl 3 ·2CH 3 CN, which reacted with bidentate donors to give complexes of formula PhZrCl 3 ·L (L = 2,2′-bipy, 4,4′-bipy or Ph 2 PCH 2 CH 2 PPh 2 ). The adducts were characterised by analysis, NMR and infrared spectroscopy.

The reaction of RTiBr3 (R = methyl, phenyl and p-tolyl) with some monodentate and bidentate ligands

Abstract RTiBr 3 (R = CH 3 , C 6 H 5 and (4-CH 3 )C 6 H 4 ) forms 1/2 adducts, RTiBr 3 2L, with a number of monodentate ligands containing nitrogen, oxygen ad sulphur donor atoms. Bidentate ligands normally give 1/1 adducts, as do the bulky monodentate ligands (C 6 H 5 ) 3 PO. Dioxan gives 1/1 adducts with CH 3 TiBr 3 and C 6 H 5 TiBr 5 but a 1/2 adduct with (4-CH 3 )C 6 H 4 TiBr 3 . Structures are assigned on the basis of IR and NMR data.

A π-allyl to σ-allyl rearrangement: The isolation of (di-π-cyclopentadienyl)-(σ-allyl)(carbon disulphide)niobium and its reaction with alkyl halides

Abstract A π-allyl to σ-allyl rearrangement occurs when (π-C 5 H 5 ) 2 (gs-allyl)Nb reacts with CS 2 to give (π-C 5 H 5 ) 2 (σ-ally)Nb(CS 2 (I); I reacts with RI to give (π-C 5 H 5 ) 2 (σ-allyl)Nb(CSSR)I.

Crystal structure of benzyltriphenylphosphonium pentachlorosulphido-tungstate(VI) and a study of the vibrational spectra of salts containing [WCl5Y]–(Y = O or S) ions

The salt [PPh3(CH2Ph)][WCl5S] is formed when WCl4S is treated with [PPh3(CH2Ph)]Cl (1 : 1 molar ratio) in Ch2Cl2 solution. Crystals are monoclinic, space group P21/c, with a= 10.572(9), b= 18.413(13), c= 14.250(11)A, and β= 104.20(8)°. The salt consists of discrete [PPh3(CH2Ph)]+ and [WCl5S]– ions with the W–S bond length being 2.132(13)A and the W–Cl lengths spanning the range 2.246(17)–2.461(12)A. The i.r. and Raman spectra of a series of salts containing the [WCl5Y]– anion (Y = O or S) have been recorded and are reported, together with an assignment of the a1 stretching modes.

Ambient temperature preparations of thio-, seleno-, and oxo-halides of niobium, tantalum, molybdenum, tungsten, and rhenium

The isolation of a large range of thio-, seleno-, and oxo-halides has been achieved by allowing Sb2Y3(Y = O, S, or Se) to react with a metal halide at room temperature with carbon disulphide as solvent.

Adducts of molybdenum(V) trichloride sulphide

The compound MoCl3S reacts with methyl cyanide to give MoCl3S,MeCN and MoCl3S,2MeCN, which have been characterised as containing six-co-ordinate molybdenum with bridging Mo–S–Mo and terminal MoS bonds respectively. The complex MoCl3S,2MeCN reacts with other ligands; 1,4-dioxan and 1,2-bis(methoxy)-ethane give adducts MoCl3S,2diox and MoCl3S,bme, while pyridine gives the salt [Hpy][MoCl4S,py] and 1,10-phenanthroline reduces molybdenum to the quadrivalent state in forming MoCl2S,phen. Direct reaction of MoCl3S with py gives MoCl3S,3py (one py being in the lattice). The salts WCl3S and MoCl3S did not react with any of the ligands tried even after prolonged reaction periods.

Preparation of halide sulphides and halide selenides of molybdenum and tungsten

A study has been made of a number of methods for the preparation of halide sulphides and halide selenides of molybdenum and tungsten in several oxidation states and the relative merits of the methods are discussed. The method of most general application is reaction of Sb2S3 or Sb2Se3 with the appropriate halide. In the case of WSCl4 the best preparative method is by reaction of sulphur with WCl6. Halide sulphides and selenides of molybdenum(IV) and tungsten(IV) are formed in the thermal decomposition of the corresponding quinquevalent compounds. The properties of these compounds are reported. Attempts to make similar tellurium compounds have been unsuccessful.