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The Schiff-base dianion N,N'-2,2-dimethyltrimethylenebis[salicylideneiminate(2-)] (salnptn) coordinates to vanadium( w ) to form [VO(salnptn)] whose crystal structure has been determined. The compound is polymeric in the solid state with -. V=O ---V=O -+ V=O chains, the salnptn donor atoms being coplanar and the salnptn framework umbrella-shaped. In the derivative [VO(OMe)(salnptn)], the crystal structure of which has also been determined, the OMe and the vanadyl oxygen are co-ordinated cis to each other, and the salnptn now occupies three equatorial and one axial coordination positions. Even N,N'-ethylenebis(salicy1ideneiminate) seems to behave analogously, though it is normally planar.We have recently described a series of vanadium(1v) complexes of tetradentate dianionic Schiff bases.' It is now well established that vanadyl(rv) compounds with such ligands are essentially five-co-ordinate, but they fall into two classes, one of green compounds with v(V=O) ca. 980 cm-' in which the five-coordinate species are without obvious intermolecular interactions in the crystal, and another which are yellow-brown, with v(V=O) ca. 880 cm-l and which appear to 'polymerise' in the crystal, forming V=O --+ V=O --V=O chains, though the 0 -V co-ordinate bond is rather long, ca. 2.2 8, compared with ca. 1.6 8, for V=0.2 Among the compounds we prepared was wO(2-OC6H4-CH=NCH,CMe2CH2N=CHC6H40-2)] ' or wO(salnptn)] which shows v(V=O) at 871 cm-' and is orange, suggesting a polymeric structure in the solid, but its solubility in organic solvents is nevertheless very high. Accordingly we undertook an X-ray crystal-structure analysis to determine whether the colour and IR data, or the solubility, is the more reliable indicator of the solid-state configuration.

The preparation and some physical properties of complexes of the types [MX,L,] where M = Re, Ru, or 0 s and [MX,L,] where M = Re, 0 s . or Ir and L = tertiary monophosphines are described. A few tertiary monoarsine analogues are also included.

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The complex [VO(salen)] [H,salen = N,N'-ethylenebis(salicylideneimine)] reacted with HBF,*Et,O in air to produce the novel linear species [{VO(salen)},(p-F)]', the structure of which has been determined as its BF,-and [VO,F,] -salts. The perchlorate and triflate (O,SCF,-) salts have been characterised spectroscopically and analytically, as well as the tetrafluoroborate homologues from salicylaldehyde and 2-methylpropylenediamine, and from ethylenediamine and 3-methoxysalicylaldehyde. The [VO,F,] is mononuclear in the above salt, as well as in [PPh,][VO,F,], compared t o a polynuclear form found in [NH,] [VO,F,]. The mononuclear anion was also fully characterised by 19F and 51V NMR spectroscopy.

The reaction of co-ordinate8 dinitrogen in a well defined manner to form organonitrogen ligands was first noted in the reaction of organic acid halides with [M(N,),( dppe),][dppe = 1 ,Z-bis( diphenylphosphino)ethane] and [ReCl(N,)(PMe,Ph),L] to form acyl-and aroyl-diazenido-complexes.3 Since then there have been brief reports of the reactions of the molybdenum and tungsten bis(dinitrogen) complexes with alkyl halides under irradiation to give alkyldiazenido-and related complexes,4*5.11,12 and with tetrahydrofuran (thf) to form complexes which were tentatively described as tetrahydropyridazido-complexes 1, but were recently shown to be w-diazobutanol c0mp1exes.l~ Here we describe in detail the work briefly reported in refs. 3 and 4. RESULTSAcyldiazenido-and Aroyldiazenido-complexes and their Derivatives --,4cyl and aroyl halides react with the com-(PR3)J (py = pyridine) to form acyldiazenido-and aroyldiazenido-complexes.3 The products containing molybdenum or tungsten are most easily isolated as the hydrochlorides, formulated [MC1,(N2HCOR) (dppe),] (R = alkyl or aryl). One mol of hydrogen chloride can be removed by plexes [M(N,) z(dPP4 21. tReCI(N2) (PR3)4J 2 or [ReCW,) (PYb pqx,).(dppe),] -t-RCOC~ -1-HCI + [NICl,(N,HCOR) (dppe) ?] NEt, HCI [i?ICl( N,COII) (clppe) ,] ( 1)bases, as shown in (1). Acylation and aroylation of the rhenium dinitrogen complexes analogously yield [ReCl,-(N,COR) (PRJJ, b u t the resulting diazenido-ligand is not protonated by hydrogen chloride. These complexes (with R = aryl) have been obtained previously from aroylhvdrazines,15 but the acyldiazenido-complex is the first of its type. The complexes [OsCl,(N,) (PR3)3], which are isoelectronic in the valence shell with the rhenium, molybdenum, and tungsten complexes, do not react with acyl or aroyl halides, even in toluene under reflux.

The title compounds of the general type (I) have been prepared from Ti(C5I‐I5)C13 and the appropriate trimethylsilylhydrazine in Et2O with a yield of about 90%.