3,361,779 United States Patent Office Paterated Jan. 2, 1968 1. 2 bon of the aromatic ring is bonded apparently by co 3,361,779 ORGANOMETALLC COMPOUNDS ordinate covalence in a fashion such that the ring con Thomas H. Coffield, Heidelberg, Germany, and Rex D. tributes six electrons to the metal atom. Likewise, the Closson, Northville, Mich., assignors to Ethyl Corpo other electron donor groups also are covalently or co ration, New York, N.Y., a corporation of Virginia 5 ordinatively bonded to the metal atom. Such donation of No Drawing. Filed Aug. 20, 1959, Ser. No. 834,931 electrons contributes materially to the stability of the 18 Claims. (Cl. 260-429) molecule since the metal atoms, with the donated elec trons, approaches the electron configuration of the next This application is a continuation-in-part of my earlier higher rare gas. In a preferred embodiment of this inven filed copending application, U.S. Ser. No. 690,909, filed on () tion the compound has the electron configuration of the Oct. 18, 1957, now abandoned. next higher rare gas. For example, the chromium atom in This invention relates to novel organometallic com benzene chromium tricarbonyl has the electron configura pounds and their preparation. More particularly the pres tion of krypton. Thus, in the case of benzene chromium ent invention relates to novel and useful aromatic transi tricarbonyl, the three CO groups donate a total of six tion metal complexes. electrons and the benzene molecule donates six electrons, An object of this invention is to provide a novel class giving a stable compound which can be illustrated as foll of organometallic compounds. Another object is to pro lows: wide a novel class of stable aromatic transition metal co ordination compounds. A further object is to prove a novel class of stable non-ionic aromatic metal complexes having unsymmetric configurations. A still further object is to pro vide a class of stable non-ionic aromatic transition metal The novel aromatic metal compounds of this invention complexes in which a single aromatic molecule is coordi find a number of uses. In particular, the compounds are nated with a metal atom. Other objects will become ap valuable as polymerization catalysts in the polymeriza parent from the following discussions. 25 tion of unsaturated hydrocarbons wherein they have the The above objects are accomplished by a non-ionic com advantage of supplying the aromatic molecule which is plex aromatic metal compound of the metals of Groups sometimes necessary to promote polymerization and in ad IV-B through VI-B having a single aromatic molecule dition are soluble both in the hydrocarbon itself, the sol bonded to the metal through the carbon atoms of the ben vent medium, and the resulting polymers. Further, the Zene ring, which compound is stabilized by additional co 30 compounds of this invention are useful as dryers in organic valent bonding to dissimilar electron-donating groups. The drying oil compositions and as metal sources in gas-phase metal in the novel compounds of this invention is a metal plating. of Groups IV-B, V-B and VI-B of the Periodic Table as The aromatic compounds coordinated to the metal in shown in the Handbook of Chemistry and Physics (37th the compounds of this invention, which are represented by edition; the Chemical Rubber Publishing Co., Cleveland, 35 A in the above formula, are, in general, compounds con Ohio, 1955) on pages 392 and 393, and thus includes those taining an isolated benzene nucleus. That is, aromatic metallic elements having atomic numbers of from 22 compounds which are free of aliphatic unsaturation on a through 24, 40 through 42 and 72 through 74. carbon atom adjacent the benzene ring and which do not The compounds of this invention may be represented by contain unsaturation on a carbon atom of a fused ring the formula 40 which carbon atom is adjacent the benzene nucleus. The AMQ aromatic compounds applicable to the compounds of this wherein A represents an aromatic compound having a invention have no aliphatic double bond in conjugated benzene nucleus coordinted to the metal atom, M, through relationship to the ring. Thus, aryl and alkyl substituted the carbon atoms of the benzene ring and Q represents aromatic compounds are applicable to this invention, as discrete combinations of non-aromatic electron donor are fused ring compounds having isolated benzene nuclei, groups involved in covalent or coordinate-covalent bond that is, having no unsaturation on a carbon atom adjacent ing with the metal atom. to the benzene ring. Aromatic compounds having from 6 These novel compounds achieve stabilization through to 18 carbon atoms are generally preferred in compounds coordination of sufficient electrons to give the metal atom of this invention. Benzene itself, mesitylene, toluene, bi the electronic configuration similar to that of the next 50 phenyl, Tetralin, m-hexyl-biphenyl and the like are ex higher rare gas. The compounds of this invention can also amples of applicable aromatic compounds. be represented by the formula In some cases, other aromatic compounds which do not have an isolated nucleus are desirable. Typical examples AM (B)(C) of such compounds are styrene cyclopentadienyl chloro wherein A and Mare defined above and B and C represent 55 chromium, methyl-styrene cyano vanadium tricarbonyl, electron-donating entities capable of donating form 1 to 8 naphthalene dichloro titanium dinitrosyl, anthracene di electrons to the metal atom, b is an integer ranging from ethylmolybdenum dimethylene diamine, 1-ethyl naphthal 1-8, and c is an integer ranging from 0-4, such that the ene amylvanadium tricarbonyl, and the like. atomic number of the metal M, plus b times the number The metal constituent in the compounds of the present of electrons donated by b, plus c times the number of elec 60 invention are transition metal elements of the fourth, fifth trons donated by C plus the six electrons donated by the and sixth periods of the Periodic Table. These elements aromatic molecule A equals an integer having a value of constitute Groups IV-B, V-B and VI-B of the Periodic from two less than the atomic number of the next higher Table and include, in group IV-B, titanium, zirconium rare gas to the value of the next higher rare gas. and hafnium; in Group V-B, vanadium, niobium, and The compounds of this invention are quite different tantalum; and in Group VI-B, chromium, molybdenum from any compound heretofore known. The aromatic por and tungsten. tion of the compound is actually a molecule, as distin The constituents represented by B and C in the above guished from an aryl radical, e.g., phenyl, which is found formula are electron-donating groups capable of coordi in organometallic compounds. The aromatic molecule is 70 nating with the metal atom in the novel compounds of not bonded to the metal through a single carbon atom, as this invention, and donating thereto from 1 to 8 electrons. in the usual aryl metal compounds but, instead, each car That is, the groups represented by B and C in the above 3,361,779 3 4. formula are capable of sharing electrons with the metal amine, benzene vanadium nitrosyl butadiene, amyl atom so that the metal achieves a more stable structure benzene chromium cyclohexadiene carbonyl, toluene tri by virtue of such added electrons. A preferred embodi methyl hafnium N,N'-diphenylmethylenediamine, toluene ment of this invention comprises those compounds in dicyano zirconium cyclohexadiene and the like. which the metal has attained the electron configuration A preferred cyclic diolefin donor used in forming the of the next higher rare gas by virtue of the coordinating compounds of our invention is cyclopentadiene. Com groups, as it is found that these compounds have excep pounds in which an aromatic molecule, as defined above, tional stability. and a cyclopentadiene molecule are both coordinated with These electron-donating groups in coordination with a metal atom of Groups IVB-VIIB, are stable and have the metal are, generally, either organic radicals or O the characteristics of volatility and fuel solubility which molecular species which contain labile electrons, which make them more valuable as gasoline additives than electrons assume more stable configuration in the molecule certain of the other compounds of our invention. The when associated with the metal. The electron-donating cyclopentadiene molecule may contain from 5 to about groups applicable to the compounds of this invention may 13 carbon atoms and may be substituted with various also be inorganic entities which are capable of existing groups such as alkyl, aryl, cycloalkyl, halogen nitro groups as ions, such as hydrogen, the cyanide group, and the and the like. Typical of such compounds are mesitylene various halogens. titanium cyclopentadiene dicarbonyl, toluene zirconium Donors capable of sharing a single electron with a methylcyclopentadiene dicarbonyl, hexamethylbenzene metal atom include monovalent organic radicals, the hy niobium cyclopentadiene nitrosyl, chlorobenzene vana drogen atom, the cyanide group CN, and the halogens, 20 dium trichloromethylcyclopentadiene carbonyl hydride, fluorine, chlorine, bromine and iodine. These groups Xylene dichloro chromium nitrocyclopentadiene, N,N- function as electron donors by sharing an electron with diethylaniline molybdenum cyclopentadiene carbonyl and an electron of the metal atom in a single covalent bond. anisole chromium benzylcyclopentadiene triphenylphos Examples of the aromatic metal coordination compounds phine. of this invention containing such a donor group include 25 The cyclopentadienyl radical contributes five electrons toluene heptabutyl zirconium, mesitylene tetracyano tri to certain of the novel aromatic metal coordination com chloro vandium, ethylbenzene tribromo trihydro molyb pounds of this invention. The cyclopentadienyl radical denum, benzene hexaethyl chromium, isopropyl benzene found in these novel compounds contain from 5 to about heptabromo tantalum, benzene octachloro titanium and 13 carbon atoms and thus includes the substituted cyclo the like.