Group VB

Group VB.—Depending on the reaction conditions, SbC reacts with [Mn-(CO)2Cp(THF)] to give either [ Mn(CO)2Cp 2Cu-Sb Mn(CO)2Cp Cl)], which contains a 3-membered Mn2Sb ring, or [ Cp(CO)2MnSbCl2 2Mn(CO)2Cp], which contains a chain of metal atoms.  

Substitution Reactions of Metal and Organometal Carbonyls with Group V and VI Ligands 

In an account of his forty years work on metal carbonyl-liquid ammonia systems, Behrens includes information on [M(CO) Lj,] complexes (L=NH3, bipy, phen, or terpy). Reviews have also appeared on alkylaminobis(difluoro-phosphine) complexes, cyclometallations involving phosphorus donor ligands, and optically active species/ 

The phosphinie complexes [M(CO)n(PhaPCH=CHCH=CHPh)], M = Fe, = 4 M = Mo, n = 5), prepared from the newly synthesized -buta-l,3-dienyl-phosphine, react with [Fes(CO)i2] to afford the dimetallic complexes [(OC)nM-(PhaPCH=CHCH=CHPh)Fe(CO)3] containing an iron- -diene moiety. The complexes [M(CO)n(PhPHPR3)m] (M=Mo, n = 4 or 5, m=2 or 1, R = Ph or But M = Fe, = 4, m=l, R = Ph) and the related [ M(CO) a /M-PPh(H)P(Ph)-P(Ph)H ] have also been isolated. The presence of both P—H bonds and unligated phosphine groups in these compounds permits the subsequent preparation of 

Savignac, P. Cadiot, and F. Mathey, Inorg. Chim. Acta, 1980, 45, L 43. 

Although not yet published in a journal, according to thesis work, the vanadium compounds VSCl (11), VSBr, and VSI (208) seem to exist. Numerous niobium chalcogenide halides have been reported, and among these are the best characterized examples of Group VB (see Table X). Only two tantalum compounds, TaS2(IIl2 (361) and TaSCU (13] have thus far been described in the literature. 

Compound Preparation Crystallo- graphic data Optical properties Magnetic data Other physical data 

The reaction starts at room temperature. The BCI3 formed is condensed in a side arm cooled by liquid nitrogen. 

By mixing solutions of sulfur and the pentachlorides of niobium and tantalum in benzene in a dry, inert atmosphere at room temperature, fine crystalline powders are formed having the compositions NbS2Cl and TaSaClz, respectively (361). By the direct interaction of sulfur with the pentachlorides in a sealed tube at 240-300°C, a reaction product sublimes it has the composition M(S2)mCln where M is Nb or Ta, and m = 1-3, n = 1-4, depending on the initial ratio of MCI5 to S. 

The platelike crystals of the compounds NbY2X2 are stable in air, and dissolve in hot HNO3 with precipitation of Nb20s, and in 20% KOH-H2O2, affording a clear solution. At 10 torr, they completely decompose as follows. 

In the presence of 18-crown-6, potassium metal, and THF, [(l2PhSb)Mn(CO)2-Cp] and [Mn(CO)a(THF)Cp] give [(//-PhSb) Mn(CO)aCp 2], which contains the phenylstibanediyl ligand and near trigonal-planar antimony.  

Other published studies relevant to this Chapter include  

Johnson and R. E. Benfield, J.C.S. Dalton, 1978, 1554. Carbonyl scrambling in [M4(CO)i2] (M = Co, Rh, or Ir) explained in terms of disposition of metal tetrahedron within ligand polyhedron. 

Collins, F. A. Cotton, S. A. Koch, M. Millar, and C. A. Murillo, Inorg. Chem., 1978, 17, 2017. Details of Z-ray structures of Li4[W2Mea],40Et2 and Li4[WaMe8-nCln],4THF. 

Jackson and A. Poe, Inorg. Chem., 1978,17, 997. Kinetic measurement of metal-metal bond strengths of [Mn2(CO)io] and related derivatives. 

There are two magnetic vanadium nuclei V (JV= 99.76%, 7=7/2) and (0.24%, 1=6), and from the natural abundances it is clear why practically all investigations have been carried out on V. This is one of the most suitable nuclei for NMR experiments, considering its high receptivity (0.381) and low Q (—0.052X 10 m ) which, in general, gives rise to sufficiently narrow lines even in compounds where there is virtually no symmetry. 

Nuclear quadrupole coupling constant (polycrystalline samples if not indicated otherwise) absolute errors in parentheses. Chemical shifts and linewidths are given for isotropic systems (neat liquids or solutions). 

From quadrupole splittings in nematic liquid crystals. 

P(CH2CH2PPh2)2] to low frequency of the unresolved signal for the meridional isomer ( — 1734 ppm).  

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This group may be further subdivided into Group VA—soluble in concentrated sulphimic acid and soluble in 85 per cent, phosphoric acid— and Group VB—soluble in concentrated sulphuric acid and insoluble in 85 per cent, phosphoric acid. 

V (various compounds) Group VB N Methanol Aromatic diadds 68... 

Reaction of an alkyl (usually trimethyl) of Group-IIIb element (Al, Ga, In) with a hydride of a Group-Vb element (P, As, Sb) at 600-800°C and 1 atm. [4i][42] p. doping obtained from addition of diethyl zinc or bis(cyclopentadienyl) magnesium. 

The CVD of the III-V compounds is usually obtained by reacting an alkyl of a Group-IIIb element with a hydride of a Group-Vb element. These reactions have largely replaced the co-reduction of the halides, The general reaction is as follows ... 

Just as, in Group VB, niobium, so, in this Group, molybdenum provides most of the examples of the chalcogenide halides. The occurrence and preparation of such compounds are described in numerous publications. In most cases, they have been obtained as powders, with the composition based on chemical analyses only. The presence of defined, homogeneous phases is, therefore, in many cases doubtful. In addition, some published results are contradictory. A decision is possible where a complete structure analysis has been made. As will be shown later, the formation of metal-metal bonds (so-called clusters), as in the case of niobium, is the most characteristic building-principle. Such clusters... 

Table 4. Sintering Characteristics of Diborides of Group-VB Metals (VBj, NbBj, TaBj)...

Ligands that reduce the activity of Hg(II) more than that of Hg(I) lead to disproportionation products when added to a solution containing Hg2 ions. Because the smaller Hg ion is a better electron-pair acceptor acid than the larger Hgj ion, the number of Hg(I) complexes may be limited, but many complexes of Hg(I) are formed by reactions of Hg, with ligands containing donor atoms from groups VB and VIB. Polyethers and polyesters are good solvents for these reactions, ... 

Intrinsic Activity Poisons. These poisons decrease the activity of the catalyst for the primary chemical reaction by virtue of their direct electronic or chemical influence on the catalyst surface or active sites. The mechanism appears to be one that involves coverage of the active sites by poison molecules, removing the possibility that these sites can subsequently adsorb reactant species. Common examples of this type of poisoning are the actions of compounds of elements of the groups Vb and VIb (N, P, As, Sb, O, S, Se, Te) on metallic catalysts. 

George, J. W., Halides and Oxyhalides of the Elements of Groups Vb and Vlb George, Philip and McClure, Donald S., The Effect of Inner Orbital Splitting on the Thermodynamic Properties of Transition Metal Compounds, and 2 33... 

Group 4 (IVB) perchlorates, 28 278 Group VB metal carbides, 4 650-651 cemented carbides, 4 655 preparation, 4 650-677 Group 5 (VB) hydrides, 13 627 Group V hydrides, compound... 

We do not believe that an Fe X2 valence formulation (32, 42) is supported by the shift data for the group Vb dianion compounds. The shifts are so similar for the Vb and VIb compounds that it is highly unlikely we are dealing with Fe It is also rather implausible that a... 

Fig. 17 a One-dimensional electron density distribution of Ca2Al/VBS along the c axis b Gaussian deconvolution of the hydroxide layer c Gaussian deconvolution of the interlayer space and the resulting conformation of VBS molecules in C2/c space group, VBS molecules are related by an helicoidal axis 2 located midway in the interlamellar space... 

Arsenic and antimony are Group VB elements and both occur in soils predominantly in - -3 and - -5 oxidation states and they have similar redox and sorption behaviour. The oxidized forms are rather insoluble in soils and the reduced forms much more soluble. 

Symbol Nb atomic number 41 atomic weight 92.906 a Group VB (Group 5) element a transition metal in the triad of vanadium and tantalum also. 

The group IV B elements titanium, zirconium, and hafnium exhibit the normal isotope effect. Most of the data for the titanium-hydrogen system have been obtained at elevated temperatures. However, extrapolation of the available data (II, 13,31) to room temperature indicates a normal effect for hydrogen and deuterium. The group VB metals vanadium, niobium, and tantalum, on the other hand, exhibit inverse isotope effects indeed, these are the only pure metals that exhibit the inverse effect near room temperature. Extensive data have been reported for these systems. The P-C-T data obtained by Wiswall and Reilly (32) for vanadium hydrogen and deuterium clearly show a greater stability for... 

Titanium Salt Components Group VB Other Usea... 

Compared to vanadium, the higher oxidation states are much more frequently and the lower ones much less frequently encountered in niobium and tantalum. Niobium and tantalum are also much more prone to extended metal-metal bonding in their lower oxidation states V6-based clusters, for example, remain undiscovered. Little resemblance is found to the group VB elements phosphorus and arsenic. 

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