Group 4 titanium

Diaminocarbene complexes were reported as early as 1968 [152], Preparation and applications of such complexes have been reviewed [153], Because of 7t-electron donation by both nitrogen atoms, diaminocarbenes are very weak tt-acceptors and have binding properties towards low-valent transition metals similar to those of phosphines or pyridines [18,153]. For this reason diaminocarbenes form complexes with a broad range of different metals, including those of the titanium group. Titanium does not usually form stable donor-substituted carbene complexes, but rather ylide-like, nucleophilic carbene complexes with non-heteroatom-substituted carbenes (Chapter 3). 

There is only one reported mononuclear hydrazido(2—) complex for the titanium group, [Ti(r/5-CjHj)2(NNSiMe3)2].498 Other hydrazido complexes are known but involve bridging hydrazido groups (see below). For reasons not yet fully understood, titanium is apparently reluctant to form four electron metal-nitrogen multiple bonds. 

The abundances of the elements of the titanium group were compared to those of the zinc group in Table 13-1. It will be recalled that unlike the zinc group metals, which are rare but easily isolated, the titanium group metals are abundant, but purified with difficulty. Note from the (very rough) figures given that titanium is 50 times as abundant as zinc, zirconium is 3000 times as abundant as cadmium, and hafnium 30 times as abundant as mercury. 

Methods of Preparation—Alkali Phosphides—Alkaline Earth Phosphides— Copper, Silver and Gold Phosphides—Zino Group Phosphides—Boron and Aluminium Phosphides—Titanium Group Phosphides—Tin and Lead Phosphides—Arsenic, Antimony and Bismuth Phosphides—Chromium, Molybdenum and Tungsten Phosphides—Manganese Phosphides—Iron, Cobalt and Niokel Phosphides—Platinum Phosphides. 

Beckhaus, R., Santamaria, C. Carbene complexes of titanium group metals -formation and reactivity. J. Crganomet. Chem. 2001,617-618, 81-97. 

Maidanovskaya, L.G. and Skipko, T.V., Adsorption of pyridine and phenol from n-hexane by titanium-group metal oxides, Zh. Fiz. Khim., 46, 115, 1972. 

The titanium group comprises titanium, zirconium, hafnium and thorium. 

SAL/SHE] Sale, F. R., Shelton, R. A. J., Studies in the chemical metallurgy of the titanium group metals I. The vapour pressure over solid zirconium tetraiodide, J. Less-Common Met., 9, (1965), 54-59. Cited on page 175. 

PANI Composites with Oxides of the Titanium Group of Transition Metals... 

Cerium will [have to] be located in accordance with the value of its atomic weight following caesium 133 and barium 137, and in accordance with the formula of its higher degree of oxidation it should be located in the titanium group, i.e., in the place IV-6. ... 

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