Chromium binary compounds

Other Binary Compounds. The chromium sulfide system is very complex, with two forms of Cr2S3 and several intermediate phases between these and CrS.4 Rhombohedral Cr2S3 has complex electrical and magnetic properties.5... 

Additional data on chromium-oxygen binary compounds are found in the literature (50,56,59,62,63). 

Burdett JK, Graham MA, Turner JJ. Binary compounds of dinitrogen with nickel, chromium, platinum, and copper a vibrational investigation of the metal-dinitrogen linkage. J Chem Soc Dalton Trans. 1972 1620-1625. 

Iron carbide (3 1), Fe C mol wt 179.56 carbon 6.69 wt % density 7.64 g/cm mp 1650°C is obtained from high carbon iron melts as a dark gray air-sensitive powder by anodic isolation with hydrochloric acid. In the microstmcture of steels, cementite appears in the form of etch-resistant grain borders, needles, or lamellae. Fe C powder cannot be sintered with binder metals to produce cemented carbides because Fe C reacts with the binder phase. The hard components in alloy steels, such as chromium steels, are double carbides of the formulas (Cr,Fe)23Cg, (Fe,Cr)2C3, or (Fe,Cr)3C2, that derive from the binary chromium carbides, and can also contain tungsten or molybdenum. These double carbides are related to Tj-carbides, ternary compounds of the general formula M M C where M = iron metal M = refractory transition metal. 

The preparation of pentadienylsodium was being studied at about the same time as ferrocene was discovered. It was not until 1968, however, that the first binary pentadienyl complex of a transition element, bis(pentadienyl)-chromium, was obtained from PINa and CrCl2 (121). This compound forms green, air-sensitive crystals, and like chromocene it has two unpaired electrons (Ht = 2.74 BM). This discovery was shortly followed by that of the curious complex, bis(pentadienyl)dinickel (12) which was prepared from NiCl2 and triethylaluminium in 1,4-pentadiene (122). The pentadienyl ligands in 12... 

High-purity elements were used to synthesize the required binary and ternary compounds for further experimentation chromium pellets of 99.999 + % from United Minerals Chemical Corp. molybdenum powder or rods of 99.99 + % and 99.95 + %... 

Alcohols may be oxidized in a similar way. However, these reactions strongly resemble those reported for Cr molecular sieves, and a small concentration of Cr in solution may well account for most of the observations of catalysis. Binary molybdenum-chromium oxides supported on alumina have been used in the autoxidation of cyclohexene with 02 and r-BuOOH as an initiator (62). This is a complex reaction in which uncatalyzed and Cr-catalyzed oxidation combine to yield 2-cyclohexen-l-one, 2-cyclohexen-l-ol, and 2-cyclohexenyl hydroperoxide the Mo compound can use the hydroperoxide formed in situ as an oxidant for the epoxidation of cyclohexene. Although much lower oxygen consumption was observed for the reaction filtrate than for the suspension, it is unclear how the Cr is held by the oxide. 

Figures 11-13 depict the resolution of some binary and ternary lead and chromium compounds mixtures, as a further evidence of the reliability of the iterative combined simulated annealing-Kalman filtering procedure for the quantification of the shifted spectra. The mean errors were about 4% for binary mixtures and larger, about 10%, for ternary mixtures. This error was still acceptable considering the complexity of the unresolved ternary...

Binary and Ternary Compounds and Related Systems.—Halides. The solubility of chromium in CrCl2 has been investigated and the depression of the freezing point of anhydrous CrCl2 determined by d.t.a. and solubility measurements. The m.pt. of pure CrCl2 was found to be 1095 1 K and the eutectic was obtained at 1083 K and 3.4 0.1 mole % of Cr. From the saturation solubility curve, a value of 57.0 kJ mol" for A/f oin. of Cr in CrCl2 was obtained. ... 

Various Ziegler-Natta and ROMP caalysts based on group IV-VIII transition metal salts showed to be very active and selective in the polymerization of both exo-and ew(7o-dicyclopentadiene [151-155]. Thus, binary Ziegler-Natta systems derived from chromium, molybdenum, and tungsten halides associated with organo-aluminum compounds form addition and ring-opened polymers [Eq. (94)]. 

---