Abstract: The present invention relates to a catalyst for polymerization of &agr;-olefin, which comprises: an essential component (A) of a transition metal compound, an essential component (B) of an ion exchangeable layer compound except for silicate, or an inorganic silicate, and an optional component (C) of an organoaluminum compound, said component (A) being represented by the general formula (I):

Abstract: A modified aluminoxane is disclosed. Aluminoxane compounds are modified with glycol ethers or polyethers. The modified aluminoxanes are effective activators for single-site catalysts. Catalyst activated with the modified aluminoxane produces polyolefin with increased melt flow index, broadened molecular weight distribution, and improved thermal processability.

Abstract: A particulate, modified chromium oxide catalyst for the polymerisation of ethylene or ethylene with &agr;-olefins, comprising: a) a chromium-oxide catalyst, b) a transition metal compound, and c) a catalyst activator. A method for the preparation of the catalyst comprises the steps of: a) subjecting a chromium oxide catalyst precursor, which comprises a chromium oxide compound combined with an inorganic support, to a temperature in the range of from 400 to 950° C.

Abstract: The present invention provides an improved acyclic anionic six-electron-donor ancillary ligand suitable for being bonded in a transition metal complex. The present invention also provides a transition metal complex that includes at least one acyclic anionic six-electron-donor ancillary ligand which is suitable for use as an olefin polymerization catalyst. The complex includes a Group 3 to 10 transition or lanthanide metal and one or more anionic or neutral ligands in an amount that satisfies the valency of the metal such that the complex has a net zero charge. The present invention also discloses a method for making transition metal complex and a method for using the complex for olefin polymerization.

Abstract: A new process is disclosed, particularly simple, convenient and practical, for the direct synthesis of titanium complexes of the formula (I): (D)(ZR1m)n(A)TiLpXq, wherein (ZR1m)n is a divalent group bridging D and A; D is a delocalized &pgr;-bonded moiety, which is bound in an &eegr;5 bonding mode to Ti, and is preferably a Cp moiety; A is —O—, —S—, —N(R2)— or —P(R2)—, wherein R2 is hydrogen, alkyl, cycloalayl, aryl, alkylaryl or arylalkl; L are monoanionic sigma ligands selected from alkyl, cycloalkyl, aryl, alkylaryl and arylalkyl groups; m is 1 or 2; n is 1-3; p is 1 or 2, q is 0 or 1 and p+q=2; said process comprises reacting a ligand of formula (H—D)(ZR1m)n(A—H) with about 1 molar equivalent of TiX4 in the presence of about (2+p) molar equivalent of LjB or LMgX wherein X is halogen or —OR′, B is an alkaline or alkaline-earth metal, and j is 1 or 2.

Abstract: An organometallic compound of the formula I where M1 is selected from among Fe, Ru and Os and M2 is selected from among the transition metals of groups IV to VI of the Periodic Table, which can be prepared by reacting an organometallic compound of the formula II with a transition metal compound of the formula III, M2L1L2(L3)x+1  III where the variables are as defined above and the organometallic compound of the formula II can, if desired, be doubly deproteinated beforehand, can be used as part of a catalyst system for the polymerization or copolymerization of olefins. This catalyst system comprises one or more organometallic compounds of the formula I and at least one activator.

Abstract: A catalyst obtained by contacting a transition metal compound (A) of the general formula [1]: [LpXoCpjM(N2)nM′XmLl]X′k  [1], wherein M and M′ independently represent a transition metal of Group 3 to 10; X independently represents a hydrogen atom, halogen atom, a specific hydrocarbon group or the like; Cp is a cyclopentadienyl group; L represents a group which bonds to M or M′ by lone pair of electrons or a &pgr; electron; X′ represents a counter anion; k, l, m, o and p each independently represent an integer of 0 to 5; j represents an integer of 0 to 2; n+o+p+j≦6; n represents an integer of 1 to 3; and n+l+m≦6, with an organoaluminum, and an aluminoxane and/or boron compound, or with an aluminoxane and/or boron compound, and a process for producing an addition polymerization with the catalyst.

Abstract: A modified aluminoxane is disclosed. Aluminoxane compounds are modified with glycol ethers or polyethers. The modified aluminoxanes are effective activators for single-site catalysts. Catalyst activated with the modified aluminoxane produces polyolefin with increased melt flow index, broadened molecular weight distribution, and improved thermal processability.

Abstract: Dimetalhydroxy malate compositions as well as methods of administering and making such bioavailable compositions are provided. The metal used can be any nutritionally relevant divalent metal such as calcium, magnesium, zinc, copper, manganese, and iron. The composition can be prepared by reacting malic acid with a divalent metal oxide or hydroxide at a 1:2 molar ratio. The composition can be administered to a warm-blooded animal by any of a number of known delivery routes, including oral delivery.

Abstract: A liquid precursor for forming a transparent metal oxide thin film comprises a first organic precursor compound. In one embodiment, the liquid precursor is for making a conductive thin film. In this embodiment, the liquid precursor contains a first metal from the group including tin, antimony, and indium dissolved in an organic solvent. The liquid precursor preferably comprises a second organic precursor compound containing a second metal from the same group. Also, the liquid precursor preferably comprises an organic dopant precursor compound containing a metal selected from the group including niobium, tantalum, bismuth, cerium, yttrium, titanium, zirconium, hafnium, silicon, aluminum, zinc and magnesium. Liquid precursors containing a plurality of metals have a longer shelf life. The addition of an organic dopant precursor compound containing a metal, such as niobium, tantalum or bismuth, to the liquid precursor enhances control of the conductivity of the resulting transparent conductor.

Abstract: Dicationic or partially dicationic Group 4 metal compounds having utility has addition polymerization catalysts among other uses and a method of preparation.

Abstract: The invention comprises a chemical composition with the structure shown below. The composition can be polymerized or pyrolyzed, forming transition metal nanoparticles homogeneously dispersed in a thermoset or carbon composition. The size of the nanoparticles can be controlled by manipulating the number and arrangement of functional groups in the composition and by changing the conditions of the polymerization or pyrolysis. The resulting thermosets and carbon compositions have useful magnetic, electric, mechanical, catalytic and/or optical properties.

Abstract: This invention relates to a composition of matter comprising the catalyst compound comprising a transition metal complexed with a facially coordinating tridentate bisamide ligand. The invention is also directed to a catalyst system or a supported catalyst system comprising this compound and an activator and to a process for using the catalyst system or supported catalyst system in a process for polymerizing olefin(s).

Abstract: A class of metallocene compounds is disclosed having general formula (I) wherein Y is a moiety of formula (II) wherein A, B, and D, same or different from each other, are selected from an element of the groups 14 to 16 of the Periodic Table of the Elements (new IUPAC version), with the exclusion of nitrogen and oxygen; R1, R2, R3, R4 and R5 are hydrogen or hydrocarbon groups, Z is selected from a moiety of formula (II) as described above and from a moiety of formula (III) wherein R6, R7, R8 and R9, are hydrogen or hydrocarbon groups; L is a divalent bridging group; M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements (new IUPAC version), X, same or different, is hydrogen, a halogen, a R10, OR10, OSO2CF3, OCOR10, SR10, NR102 or PR102 group, wherein the substituents R10 are hydrogen or alkyl groups; p is an integer of from 1 to 3, being equal to the oxidation state of the metal M minus 2.

Abstract: Molecular dipolar rotors comprising a base, an axle connected to said base and oriented substantially perpendicular to said base, and a rotor portion having an electric dipole moment are provided. The molecular dipolar rotors may be attached to a surface. Arrays of molecular dipolar rotors attached to surfaces are provided. Molecular dipolar rotors are useful in preparation of small devices.

Abstract: Disclosed are novel phosphinometallocenylamides that are useful as ligands for asymmetric catalysis. The novel ligands, which are readily modifiable, contain both a phosphine and an amide functionality linked by a metallocene backbone. In addition, the novel compounds are phosphine-amides derived from a phosphine-amine, rather than a phosphine-carboxylic acid. Further, described herein are both processes to make the novel ligands as well as processes that employ such ligands in a catalytically active composition comprising one or more phosphinometallocenylamide compounds in complex association with one or more Group VIb or Group VIII metals to provide chiral products. Further, we describe exemplary catalyst complexes incorporating the novel ligands.

Abstract: Compounds and metal complexes comprising a polycyclic, fused ring ligand or inertly substituted derivative thereof having up to 60 atoms other than hydrogen, said ligand comprising at least: (1) a cyclopentadienyl ring, (2) a 6, 7, or 8 membered ring other than a 6-carbon aromatic ring, and (3) an aromatic ring, with the proviso that said 6, 7, or 8 membered ring (2), is fused to both the cyclopentadienyl ring (1), and the aromatic ring (3), polymerization catalysts, a process to prepare the novel compounds and complexes, and olefin polymerization processes using the same are disclosed.

Abstract: An allylic compound is reacted with an organozinc compound Zn(R6)2 to eliminate a group (the leaving group) from the allylic compound and to add a group from the organozinc compound to it in the presence of a copper salt catalyst and a chiral organic ligand for the copper. A novel ferrocenyl compound and a novel copper complex of the ferrocenyl compound and copper are also described.

Abstract: Conversion of cyclopentadienyl or indenyl compounds to titanium organometallic complexes by treatment with titanium tetraalkoxides is described.

Abstract: The present invention relates to novel chiral 1,1′-ferrocenylene diphosphonites and the synthesis thereof, in addition to complexes of said compounds with metals from groups VIIb, VIIIb and Ib of the Periodic Table and to the use thereof for enantioselective hydrogenation of olefins, ketones and imines, or enantioselective hydroboration and 1,4-addition to activated olefins.

Abstract: The present invention provides methods for the preparation of compounds of the formula (Formula I): LyM(CO)z wherein M is Ru or Os, each L is independently a neutral ligand, y=1-4, and z=1-5. These methods involve the reaction of Ru3(CO)12 or Os3(CO)12 with a neutral ligand in a solvent system having a boiling point higher than that of benzene at atmospheric pressure.

Abstract: The present invention is directed to a transition metal catalyst, comprising a Group 8 metal and a ligand having the structure wherein R, R′ and R″ are organic groups having 1-15 carbon atoms, n=1-5, and m=0-4. The present invention is also directed to a method of forming a compound having an aromatic or vinylic carbon-oxygen, carbon-nitrogen, or carbon-carbon bond using the above catalyst. The catalyst and the method of using the catalyst are advantageous in preparation of compounds under mild conditions of approximately room temperature and pressure.

Abstract: Disclosed are a novel transition metal compound represented by the following general formula (I), a catalyst component for olefin polymerization comprising same, a catalyst for olefin polymerization comprising said catalyst component, and a process for the preparation of an a-olefin polymer: where the definition of formula (I) is described in the specification.

Abstract: Titanium complexes comprising a 3-aryl-substituted cyclopentadienyl ring or substituted derivative thereof, polymerization catalysts, and olefin polymerization processes using the same are disclosed.

Abstract: Metalorganic precursors for deposition of strontium tantalum and strontium niobium oxides by MOCVD techniques have the formula Sr[M(OR1)6-xLx]2 wherein x is form 1 to 6; M is Ta or Nb; R1 is a straight or branched chain alkyl group; and L is an alkoxide group.

Abstract: A novel compound shown by M[N(OC2H5)5(OC2H4OCH3)]2, wherein M represents Sr or Ba, N represents Nb or Ta, which is a liquid at room temperature, is hard to be thermally dissociated, and has a vapor pressure of about 0.2 Torr at 190° C. The compound is produced by reacting 2 moles of N(OC2H5)5 and from 1 to 1.1 moles of M(OC2H4OCH3)2 and then recovering the product by distillation. By using the compounds as raw materials for a CVD method, an SrBi2Ta2O9 thin film or a (Sr0.75Ba0.25)Nb2O6 thin film for semiconductor devices can be produced.

Abstract: Novel, highly effective catalyst compositions are described in which a low cost co-catalyst can be employed at very low aluminum loadings. Such compounds are composed of a cation derived from d-block or f-block metal compound, such as a metallocene, by loss of a leaving group, and an aluminoxate anion derived by transfer of a proton from a stable or metastable hydroxyaluminoxane to such leaving group. These catalyst compositions have extremely high catalytic activity and typically have high solubility in paraffinic solvents. Moreover they yield reduced levels of ash and result in improved clarity in polymers formed from such catalysts. Surprisingly, when isolated and stored, and optionally purified, under anhydrous inert conditions and surroundings, the catalyst compounds are more stable than if kept in solution. Thus these catalyst compounds can be stored, shipped, and used under inert anhydrous conditions as preformed catalysts thus simplifying the polymerization operations.

Abstract: The invention is a polymerization catalyst system derived from tethered, heteroatom-bridged monocyclopentadienyl transition metal compound precursor from Group 4 of the Periodic Table of the Elements. The catalyst system comprises an activated, tethered pair of Group 4 transition metal compounds having a bidentate ancillary ligand system consisting of one cyclopentadienyl group bound to the transition metal and a Group 15 or Group 16 atom covalently bound to the transition metal and linked to the cyclopentadienyl group through a bridging group containing a Group 14-15 element. The ligand systems of each transition metal compound are tethered by at least one tethering group comprising a Group 13-16 element connected at both ends to either the Group 15 or Group 16 atom or the Groups 14-15 bridging group element. The catalyst system can be employed to polymerize olefins to produce a high molecular weight polymer.

Abstract: A class of metallocene compounds is disclosed having the general formula (I): wherein Y is a moiety of formula (II) wherein A, B and D, same or different from each other, are selected from an element of the groups 14 to 16 of the Periodic Table of the Elements (new IUPAC version), with the exclusion of nitrogen and oxygen; R1, R2, R3, R4 and R5 are hydrogen or hydrocarbon groups, Z is selected from a moiety of formula (II) as described above and from a moiety of formula (III): wherein R6, R7, R8 and R9, are hydrogen or hydrocarbon groups; L is a divalent bridging group; M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements (new IUPAC version), X, same or different, is hydrogen, a halogen, a R10, OR10, OSO2CF3, OCOR10, SR10, NR102 or PR102 group, wherein the substituents R10 are hydrogen or alkyl groups; p is an integer of from 0 to 3, being equal to

Abstract: A new process, particularly simple, convenient and practical, for the direct synthesis of organometallic compounds of formula(I): (A)(ZR1m)n(A′)MLpL′q  (I) wherein (ZR1m)n is a divalent group bridging A and A′; A and A′ re independently —O—, —S—, or —N(R2)—, wherein R2 is hydrogen, alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl; M is a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups; L is a monoanionic sigma ligand, such as alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl, optionally containing Si or Ge; L′ is halogen or —OR3, R3 being an hydrocarbon radical; m is 0, 1 or 2; n is 1-8; p is 1-3; q is 0-2. Said process comprises reacting the ligand (H—A)(ZR1m)n(A′—H) with about 1 molar equivalent of ML′s in the presence of about (2+p) molar equivalents of LjB or LMgL′, wherein B is an alkaline or alkaline-earth metal, s ranges from 3 to 6, and j is 1 or 2.

Abstract: Complexes of certain transition metals with certain phosphorous-nitrogen bidentate ligands are part of all of catalyst systems for the polymerization of ethylene. Under certain polymerization conditions novel, highly branched, homopolyethylenes may be produced.

Abstract: This invention is directed to a method for synthesizing a carbonyl based compound under neat conditions comprising refluxing a metal carbonyl compound with an excess of neutral ligand to produce a first mixture; evaporating any excess neutral ligand from the first mixture to produce a second mixture; and distilling the second mixture to produce the carbonyl based compound.

Abstract: The subject invention provides a binuclear metal complex having structure (I) wherein M1, and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m and n are independently +2 or +3; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl, phenyl, etc.; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocyclic ring; wherein i, j and k are integers such that 2≦i+j+k≦4; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+n−4=p×q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene, etc.

Abstract: A liquid precursor for forming a transparent metal oxide thin film comprises a first organic precursor compound. In one embodiment, the liquid precursor is for making a conductive thin film. In this embodiment, the liquid precursor contains a first metal from the group including tin, antimony, and indium dissolved in an organic solvent. The liquid precursor preferably comprises a second organic precursor compound containing a second metal from the same group. Also, the liquid precursor preferably comprises an organic dopant precursor compound containing a metal selected from the group including niobium, tantalum, bismuth, cerium, yttrium, titanium, zirconium, hafnium, silicon, aluminum, zinc and magnesium. Liquid precursors containing a plurality of metals have a longer shelf life. The addition of an organic dopant precursor compound containing a metal, such as niobium, tantalum or bismuth, to the liquid precursor enhances control of the conductivity of the resulting transparent conductor.

Abstract: Chemical vapor deposition processes utilize as precursors volatile metal complexes with ligands containing metalloid elements silicon, germanium, tin or lead.

Abstract: Racemic isomers of metal complexes of Groups 3, 4 or the Lanthanides, addition polymerization catalysts containing the same and olefin polymerization processes using the same comprising a boratabenzene group or divalent derivative thereof are disclosed.

Abstract: There is disclosed a chiral molecular magnet having characteristics exhibiting a monocrystal, a magnetic property, an optical activity, a transparent color and a relatively high transition temperature. This chiral molecular magnet is formed of a monocrystal represented by a general formula [Mn(L)]3[Cr(CN)6]2.4H2O (wherein L is optically active (R or S)-1,2-diamines and derivatives thereof or optically active (R or S)-1,3-diamines and derivatives thereof).

Abstract: The invention relates to metallocene compounds having the formula (I): (CpYq)mMRnBo  (I) wherein: Cp or each same or different Cp is a non-substituted or substituted, fused or non-fused, homo(iso)cyclic or heterocyclic cyclopentadienyl ligand, indenyl ligand, tetrahydroindenyl ligand, fluorenyl ligand or octahydrofluorenyl ligand, Y or each same or different Y is a substituent at the cyclopentadienyl ring of said ligand Cp having the following structure (II): wherein: D is an element of Group 14 of the Periodic Table (IUPAC), R1, R2 and R3 are the same or different and are each one of a hydrogen, a halogen, a substituted or unsubstituted C1-C10 hydrocarbyl group, a substituted or unsubstituted C1-C10 hydrocarbyloxy group, a C1-C12 organosilicon group, or at least two of R1, R2 and R3 form together with D a C4-C20 ring structure; M is a transition metal of Group 4 of the Periodic Table (IUPAC) and is bound to the ligand Cp or ligands Cp in an &eegr;5 bonding mode; R or each same o

Abstract: The present invention relates to a process for carbonylation of epoxide derivatives, in which the reactivity, selectivity and the yield are superior. More specifically, the present invention relates to a process for hydroformylation of an epoxide derivative in which there is utilized a transition metal catalyst having a cyclopentadienyl radical, thereby improving the reactivity and selectivity. Further, the present invention relates to a process for hydroesterification of an epoxide derivative, in which a proper catalyst is selected, and the reaction temperature and pressure are adjusted within proper ranges under the presence of a cobalt catalyst, thereby improving the product selectivity and the yield.

Abstract: The present invention relates to a catalyst for polymerization of &agr;-olefin, which comprises: an essential component (A) of a transition metal compound, an essential component (B) of an ion exchangeable layer compound except for silicate, or an inorganic silicate, and an optional component (C) of an organoaluminum compound, said component (A) being represented by the general formula (I):

Abstract: Volatile metal complexes with &agr;-sila-&bgr;-diketonate ligands containing haloalkyl, and particularly, perfluoroalkyl, substitutents are useful as metal precursors for chemical vapor deposition processes and as nanostructured materials containing fluorous domains.

Abstract: Tin alkoxide compounds are provided with accessible electrons. The tin alkoxide compound have the general formula (THME)2Sn3(M(L)x)y, where THME is (O—CH2)3C(CH3), M is a metal atom selected from Sn and Ti, L is an organic/inorganic ligand selected from an alkoxide, a phenoxide or an amide, x is selected from 2 and 4 and y is selected from 0 and 1. These compounds have applicability as base catalysts in reactions and in metal-organic chemical vapor depositions processes.

Abstract: The invention concerns novel compounds having the elements of group 11, 12 or 14; and a tridentate ligand, a method for preparing them and their use in particular as polymerisation catalyst.

Abstract: A family of trimetallic nitride endohedral metallofullerenes and their preparation are described. The trimetallic nitride endohedral metallofullerenes have the general formula A3-nXn@Cm where n ranges from 0 to 3, A and X may be trivalent metals and may be either rare earth metal or group IIIB metals, and m is between about 60 and about 200. Further, the A3-nXn@C68, A3-nXn@C78, A3-nXn@C80 families of endohedral fullerenes are described. The trimetallic nitride endohedral metallofullerenes are produced by charging a reactor with a cored graphite rod that has been filled with a metal oxide graphite mixture. The metal oxides correspond to the metals for A and X. The graphite rod is arc discharged in a helium and nitrogen atmosphere to produce the desired trimetallic nitride endohedral metallofullerenes.

Abstract: A novel Group IV elements-bridged metallocene complex is disclosed which is represented by the following formula (I): wherein R and R1 are different and are independently selected from the group consisting of &eegr;5-cyclopentadienyl group, substituted &eegr;5-cyclopentadienyl group, indenyl group, and fluorenyl group; R2 is selected from the group consisting of —N(CH3)2, —N(C2H5)2, halogen, alkoxy, —(C═O)NH2, and C6-12 hydrocarbyl group; M is a Group IVA element; and M1 is a Group IVB metal. When employing the metallocene complex to prepare olefin polymers, since it is bridged by a Group IV element, there are two catalytic sites in the single metallocene complex catalyst. Therefore, the olefin monomers can be polymerized to a bimodal olefin polymer by a single catalyst in a single reactor, resulting in lowered capital costs.

Abstract: The invention concerns solutions of alkoxides containing titanium and/or zirconium and/or hafnium and magnesium and/or calcium and/or strontium and/or barium of general formula (I): [MII(OR)2-y(OR1)y]n.[MIV(OR1)4-z(OR)2], in which: MII means magnesium and/or calcium and/or strontium and/or barium; MIV titanium and/or zirconium and/or hafnium; R is an alkyl group with 1 to 18 carbon atoms; R1 is an alkyl group with 1 to 18 carbon atoms, y has a value of between 0 to 2; z has a value of 0 and 4; and n is a number between 0.001 and 3, with the exception that n cannot be 1 when y is 2 and z is 0, or when y is 0 and z is 4. The invention further concerns the production of these alkoxides and their use.

Abstract: 2-alkyl-4-(2,6-dialkylphenyl) indenes, methods for the synthesis thereof, methods for converting such indenes to bridged metallocene ligands, methods for converting such ligands to bridged metallocenes and olefin polymerization processes in which such metallocenes are used as a catalyst or as a component of a catalyst system are described.

Abstract: A class of bridged or unbridged metallocene compounds is disclosed, wherein the cyclopentadienyl ligands have two or four adjacent substituents forming one or two alkylenic cycles of from 4 to 8 carbon atoms.

Abstract: The invention is a catalyst system including a monocyclopentadienyl titanium compound and an alumoxane component which is highly productive for polymerizing ethylene and &agr;-olefins to produce a high molecular weight ethylene-&agr;-olefin copolymer having a high content of &agr;-olefin.

Abstract: Process for the preparation of an olefin polymer using metallocenes containing specifically substituted indenyl ligands A highly effective catalyst system for the polymerization of olefins comprises a cocatalyst, preferably an aluminoxane, and a metallocene of the formula I in which, preferably M1 is Zr or Hf, R1 and R2 are alkyl or halogen, R5 is hydrogen or alkyl, R3 and R4 are alkyl, where R3, R4 and R5 may be halogenated, —(CR7R8)m—R6—(CR7R8)n— is a single- or multi-membered chain in which R6 may also be a (substituted) heteroatom, and m+n is zero or 1.