Metal-organo compounds with sterically exposed metal-metal bonds, and a method for their production

Abstract

Metal-organo complex characterized as having at least one sterically exposed metal-metal bond, and having the structure: R.sub.n M M'R.sub.n wherein R represents a ligand which may contain one or more atoms of carbon, hydrogen, oxygen, nitrogen, sulfur or phosphorus; n is an integer of from 1 to 3; M and M' each represent the same or a different transition metal; and the symbol represents at least one sterically exposed metal-metal bond. The preparative method involves the low temperature reaction between an alkali metal naphthalene in an ethereal solvent, with the dihalogenide of at least one metal-organic species. The reaction mixture is allowed to slowly warm to ambient temperatures, the solvent is evaporated, and the naphthalene sublimed at temperatures below 40° C. The remaining crude product is extracted with an organic solvent, the extract is separated from the insoluble portion, and the product recovered by evaporating the solvent. The metal-organo complex has utility as an absorbent of nitrogen when present as a contaminant in argon. .Iadd. When M and M' in the above formula are both titanium, and R is cyclopentadienyl, and n is 2 the above preparative method results in a metal-organo complex, as above defined, wherein pairs of the ligands are pi-bonded to each titanium atom, and one of these four ligands bridges the two titanium atoms by a pi-bond to one titanium and a sigma-bond to the other. .Iaddend.

I claim: .[.1. A metal-organo complex having at least one sterically exposed metal-metal bond and having the structure: 
     
        are both hafnium and R is the cyclopentadienyl ligand..].  .[.11.  A method for preparing a metal-organo complex having at least one sterically exposed metal-metal bond having the structure:   R.sub.n M  M'R.sub.n     wherein R represents the cyclopentadienyl ligand; n is an integer of from 1 to 3; M and M' each represent the same or a different transition metal selected from the group consisting of titanium, zirconium, hafnium, molybdenum and tungsten; and the symbol   represents a single or multiple, sterically exposed metal-metal bond, which comprises:   (a) admixing a halogenide of the metal-organo compound selected to supply the desired ligand, with a cold ethereal solvent solution of potassium, sodium or lithium naphthalene at a temperature between -200° C. and -25° C. and agitating the mixture for at least 2 hours;   (b) gradually warming the reaction mixture during a period of at least two hours to substantially ambient temperature;   (c) removing the ethereal solvent and excess naphthalene at temperatures under 40° C; and   (d) extracting the residue at a temperature not exceeding 40° C. to   
     
     
        obtain the metal-organo complex..].  12. The method of claim .[.11.]. .Iadd.27 .Iaddend.wherein the sodium, potassium or lithium naphthalene is prepared in situ, in the ethereal solvent, by agitating the elemental metal and the naphthalene in said solvent as a reaction medium, prior to 
     
     
        the addition of the halogenide. 13. The method of claim .[.11.]. .Iadd.27 
     
     
        .Iaddend.wherein both M and M' are titanium. 14. The method of claim 
     
     
        .[.11.]. .Iadd.27 .Iaddend.wherein both M and M' are zirconium. 15. The method of claim .[.11.]. .Iadd.27 .Iaddend.wherein both M and M' are 
     
     
        hafnium. 16. The method of claim .[.11.]. .Iadd.27 .Iaddend.wherein both M 
     
     
        and M' are tungsten. 17. The method of claim .[.11.]. .Iadd.27 
     
     
        .Iaddend.wherein both M and M' are molybdenum. 18. The method of claim .[.11.]. .Iadd.27 .Iaddend.wherein M is titanium and M' is molybdenum. 
     
     
            The method of claim .[.11.]. .Iadd.27 .Iaddend.wherein the mixing of the halogenide of the metal-organo compound selected to supply the desired ligand, with the cold ethereal solvent solution of potassium, sodium or lithium naphthalene, is effected at a temperature of -200° C. to -150° C., and the mixture is agitated at a temperature of between -100° C. and -35° C. for a period of between 2 and 60 hours, then at a temperature between -55° C. and -25° C. for a period of between 2 and 30 hours, and then is allowed to warm to ambient 
     
     
        temperature over a period of from 1 to 60 hours. 20. The method of claim 19 wherein the mixture is agitated at a temperature of between -90° C. and -70° C. for a period of between 30 to 50 hours, then at a temperature of between -50° C. and -40° C. for a period of between 10 and 25 hours, and then is allowed to warm to ambient 
     
     
        temperature over a period of from 30 to 50 hours. 21. The method of claim .[.11.]. .Iadd.27 .Iaddend.wherein the ethereal solvent is selected from the group consisting of tetrahydrofuran, dimethyl ether, and 
     
     
        1,2-dimethoxyethane. 22. The method of claim .[.11.]. .Iadd.27 .Iaddend.wherein the residue is extracted with an aromatic hydrocarbon at a temperature below -35° C., is separated from any remaining 
     
     
        insoluble matter, and is at least partially concentrated. 23. The method of claim 21 wherein a quantity of a volatile aliphatic hydrocarbon for which the product has less affinity than for the chosen aromatic hydrocarbon solvent, and which has a higher boiling point than the chosen aromatic solvent, is added to the partially concentrated extract, and wherein the combined hydrocarbon solvent extract is then evaporated to dryness at temperatures below 40° C., thereby providing the 
     
     
        metal-organo complex product. 24. The method of claim 22 wherein the aliphatic hydrocarbon added to the extract is selected from the group consisting of pentane, octane and hexane. .Iadd. 25. A metal-organo complex having the structural formula ##STR3## and giving the infrared spectrum represented by the upper curve of the accompanying drawing and giving the X-ray diffraction data shown in the herein table of Bragg spacing and relative intensity. .Iaddend. .Iadd. 
     
     
             The metal-organo complex of claim 25 containing tetrahydrofuran adduct and giving the infrared spectrum represented by the lower curve of the accompanying drawing. .Iaddend. .Iadd. 27. A method for preparing a metal-organo complex having at least one sterically exposed metal-metal bond having the structure:   R.sub.n M  M'R.sub.n     wherein R represents the cyclopentadienyl ligand; n is an integer of from 1 to 3; M and M' each represent the same or a different transition metal selected from the group consisting of titanium, zirconium, hafnium, molybdenum and tungsten; and the symbol   represents a single or multiple, sterically exposed metal-metal bond, which comprises:   (a) admixing a halogenide of the metal-organo compound selected to supply the desired ligand, with a cold substantially dry, oxygen-free ethereal solvent solution of potassium, sodium or lithium naphthalene at a temperature between -200° C. and -25° C. in a reaction vessel from which air or oxygen has been removed or replaced with an inert atmosphere, and agitating the mixture for at least 2 hours;   (b) gradually warming the reaction mixture during a period of at least one hour to substantially ambient temperature;   (c) removing the ethereal solvent and excess naphthalene at temperatures under 40° C.; and   (d) extracting the residue at a temperature not exceeding 40° C. to obtain the metal-organo complex. .Iaddend.