First transition series

The low volatility of many transition-element compounds has in the past restricted those readily available for electron-diffraction study to fairly simple molecules such as halides and carbonyls. However, as general interest in organometallic chemistry has grown, many new volatile compounds have been prepared, and electron-diffraction workers have been able to study simple transition-metal complexes containing cyclopentadienyl and other electron-donating organic systems. 

Among halides recently investigated are the tetrahedral molecules titanium tetrachloride (Ti-Cl = 2.170 0.002 A), vanadium tetrachloride (V-Cl = 2.138 0.002 A), . iand vanadium tetrabromide(V-Br = 2.30 0.02A).i  

In one of the studies of VCl, the Cl Cl vibrational amplitude was found to be abnormally large compared with that in TiCl4, and spectroscopic evidence is given supporting the view that the anomaly may be attributed to vibronic interaction in VQ4. Vanadium pentafluoride is trigonal bipyiamidal with V-F (mean) = 1.71 0.01 A. Ferric chloride, FeClj, is monomeric between 650 and 800 °C with Fe-Cl = 2.14 0.01 A supposedly it decomposes at 900 C to ferrous chloride, FeCl2, which has Fe-Cl = 2.17 0.01 A. 

Almenningen, A. Haaland, and T. Motzfeldt, in Selected Topics in Structure Chemistry, ed. P. Andersen et al., Universitetsforlaget, Oslo, a 1967, p. 105. 2, 

Cobalt acquires the krypton electron configuration in sflylcobalt tetracarbonyl, SiHsCo(CO)4. The structure is that of a trigonal bipyramid 

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PHYSICAL PROPERTIES OF THE FIRST TRANSITION SERIES ELEMENTS... 

In the chemistry of nickel, we observe the continuing tendency for the higher oxidation states to decrease in stability along the first transition series unlike cobalt and iron, the -e3 state is rare and relatively unimportant for nickel and the +2 state is the only important one. 

Copper differs in its chemistry from the earlier members of the first transition series. The outer electronic configuration contains a completely-filled set of d-orbitals and. as expected, copper forms compounds where it has the oxidation state -)-l. losing the outer (4s) electron and retaining all the 3d electrons. However, like the transition metals preceding it, it also shows the oxidation state +2 oxidation states other than -l-l and - -2 are unimportant. 

Transition metal atoms are distinguished from other atoms by their having partially filled 3d, Ad or 5d orbitals. Here we consider only metals of the first transition series. Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, in which the 3d orbital is involved. 

Manganese, atomic no. 25, belongs to the first transition series and is the principal member of Group 7 (VIIA). It has nine isotopes (1,2) (Table 1). Table 1. Isotopes of Manganese... 

Vanadium [7440-62-2] V, (at. no. 23, at. wt 50.942) is a member of Group 5 (VB) of the Periodic Table. It is a gray body-centered-cubic metal in the first transition series (electronic configuration When highly pure, it is very soft and dutile. Because of its high melting point, vanadium is referred to as a... 

Copper compounds, which represent only a small percentage of ah copper production, play key roles ia both iadustry and the biosphere. Copper [7440-50.8] mol wt = 63.546, [Ar]3/°4.t is a member of the first transition series and much of its chemistry is associated with the copper(II) ion [15158-11-9] [Ar]3i5. Copper forms compounds of commercial iaterest ia the +1 and +2 oxidation states. The standard reduction potentials, for the reasonably attainable valence states of copper are... 

In the solid state all three elements have typically metallic structures. Technetium and Re are isostructural with hep lattices, but there are 4 allotropes of Mn of which the o-fomi is the one stable at room temperature. This has a bcc structure in which, for reasons which are not clear, there are 4 distinct types of Mn atom. It is hard and brittle, and noticeably less refractory than its predecessors in the first transition series. 

As you can see from Figure 6.9, the electron configurations of several elements (marked ) differ slightly from those predicted. In every case, the difference involves a shift of one or, at the most, two electrons from one sublevel to another of very similar energy. For example, in the first transition series, two elements, chromium and copper, have an extra electron in the 3d as compared with the 4s orbital. 

Complex ions are commonly formed by transition metals, particularly those toward die right of a transition series (MCr — 3oZn in the first transition series). Nontransition metals, including Al, Sn, and Pb, form a more limited number of stable complex ions. 

The interesting part is what happens next. In the case of the following element, number 21, or scandium, the orbital energies have reversed so that the 3d orbital has a lower energy. Textbooks almost invariably claim that since the 4s orbital is already full there is no choice but to begin to occupy the 3d orbital. This pattern is supposed to continue across the first transition series of elements, apart from the elements Cr and Cu where further slight anomalies are believed to occur. 

The atomic structure of the transition metals is such that the J shell is only partly filled. The first transition series (3d) comprises Sc, Ti, V, Cr, Mn, Fe, Co, and Ni the second (4d), Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, and Ag the third (5d), Hf, Ta, W, Re, Os, Ir, Pt, and Au. Carbonyl derivatives of at least one type are found for all these metals. Although only a few are presently used in CVD, many are being investigated as they constitute an interesting and potentially valuable group of precursor materials. 

Nitrides of Metals of the First Transition Series R. Juza... 

Allen GC, Warren KD (1971) The Electronic Spectra of the Hexafluoro Complexes of the First Transition Series. 9 49-138... 

Table 1.3 contains values for two 3d cases. At KsCuFg, ATreplirreg) contributes about 40% of the total stabilization, but at Ni (aq) only 15%. This is because in the first transition series, the nephelauxetic effect increases substantially when the oxidation state increases from -i-2 to -e3. The relatively small contribution for the M (aq) ion explains why text books use this example to explain the double bowl shapes AErep(irreg) is almost exactly cancelled by the sum of AEso and ATrix, so the total stabilization is nearly equal to the orbital stabilization energy. In most other cases, A rep(irreg) is much more important and may play an important role in sustaining the Irving-WilUams rule in complex-ing reactions [32, 33]. 

Ziegler, T., Li, J., 1994, Bond Energies for Cationic Bare Metal Hydrides of the First Transition Series A Challenge to Density Functional Theory , Can. J. Chem., 72, 783. 

Harrison, J.G. (1983) Density functional calculations for atoms in the first transition series, J. Chem. Phys., 79,2265-2269. 

From the data of Tabic 6-4, determine which charge is most common for first transition series elements (those elements in period 4 among the transition groups). 

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