Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2001-02-02
2002-08-27
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C556S001000, C556S009000, C556S010000, C556S020000, C556S028000, C556S042000, C556S057000, C534S011000, C534S015000, C502S103000, C502S117000, C526S126000, C526S160000
Reexamination Certificate
active
06441211
ABSTRACT:
The present invention relates to a new process, particularly simple, convenient and practical, for the preparation of organometallic complexes; more specifically, it relates to a process for the direct synthesis of non-cyclopentadienyl Group IV metal complexes, wherein the metal atom is linked to two sigma ligands selected from the group consisting of linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl and C
7
-C
20
arylalkyl radicals, optionally containing Si or Ge atoms.
These complexes are useful as catalyst components, e.g. in the polymerization, oligomerization and hydrogenation of olefins, in association with alumoxanes and/or compounds able to form alkylmetal cations.
PRIOR ART DISCLOSURE
Homogeneous catalytic systems based on Group IV metal complexes containing chelating diamido or dialkoxide ligand systems are well known in the state of the art and their use in olefin polymerization reactions has recently received increasing attention. These complexes are usually employed as dihalide or dialkyl derivatives, in association with suitable cocatalysts, such as alumoxanes and borate salts; dichloride metal complexes are the most commonly used derivatives.
Dialkyl metal complexes are synthesized by passing through the corresponding dihalide derivatives, which are hydrocarbylated by ligand exchange with an appropriate hydrocarbylating agent to the target products; total yields are generally unsatisfactory and the following process steps are required:
(1) preparing the dihalide metal coordination complex by reacting a suitable ligand, usually silylated or derivatized with suitable leaving groups, with MX
4
(usually TiCl
4
or ZrCl
4
);
(2) converting the dihalide complex obtained in step (1) into the corresponding dialkyl complex, by substitution of the halogens linked to the metal atom with the desired alkyl or aryl groups, by means of an alkylating agent such as alkyllithium, dialkylmagnesium or the corresponding Grignard reagent.
Therefore, dialkyl complexes can not be expediently synthesized by the existing methodology. For instance, J. Okuda et al. (
Chem. Ber.
128: 221-227, 1995) described the preparation of a class of titanium complexes containing bidentate bis(phenoxy) ligands; dimethyl complexes were synthesized by the reaction of the corresponding dichloride derivatives with Grignard reagents, such as methylmagnesium bromide, at −78° C.
D. McConville and coworkers (
Journal of Molecular Catalysis A: Chemical
128:201-214, 1998) described the reaction of RHN(CH
2
)
3
NHR (wherein R is aryl) with 2 equivalents of BuLi, at −78° C., followed by 2 equivalents of ClSiMe
3
, at 0° C., to produce the silylated diamine ligand R(Me
3
Si)N(CH
2
)
3
N(SiMe
3
)R; this diamine ligand was then treated with TiCl
4
to yield the dichloride complex [RN(CH
2
)
3
NR]TiCl
2
in unsatisfactory yields. Without the previous silylation of said diamine ligand, the reaction of the ligand dilithium derivative with TiCl
4
(THF)
2
gave very low yields (<10%). The dichloride complex [RN(CH
2
)
3
NR]TiCl
2
was then reacted with 2 equivalents of MeMgBr, to give the dimethyl derivative [RN(CH
2
)
3
NR]TiMe
2
. These complexes are active catalysts for the polymerization of &agr;-olefins, and in particular 1-hexene.
With regard to alternative synthetic strategies for the production of metal diarnido complexes, the M(NR
2
)
4
precursor amine elimination approach has provided in general a more efficient preparation than conventional salt elimination synthetic routes (see R. Schrock et al.,
Organometallics,
17:4795-4812, 1998).
However, this route usually leads to a myriad of undesired products and, for subsequent catalysis, it is critical that the amido complexes be converted to dichloride or dialkyl polymerization catalyst precursors, because amido-derived catalysts are significantly less active than chloride or alkyl-derived catalysts.
More specifically, as reported by R. Schrock in the cited reference, the reaction between M(NMe
2
)
4
and a diamine ligand produced the corresponding M(NMe
2
)
2
complex, which was then reacted with an excess of Me
3
SiCl in ether to form the MCl
2
complex; finally, the dichloride species was alkylated by using a Grignard reagent to afford the corresponding dialkyl complex, in unsatisfactory final total yields.
Also in this case, in order to achieve the desired dialkyl metal complex, it is necessary to pass through the metal dihalide derivative, thus requiring numerous reaction steps and lowering total reaction yields. Therefore, the prior art processes for producing metal complexes having hydrocarbon sigma ligands bonded to the central metal atom are inadequate for a commercially viable and practical production of said complexes, for use as catalyst components in olefin polymerization; it is felt the need for a simpler and more convenient and practical method to produce these complexes in satisfactory yields.
SUMMARY OF THE INVENTION
The Applicant has now unexpectedly found a new process for the preparation of organometallic complexes of formula (I):
(A)(ZR
1
m
)
n
(A′)ML
p
L′
q
(I)
wherein:
(ZR
1
m
)
n
is a C
1
-C
50
divalent group bridging A and A′, Z being C, Si, Ge, N, P, O or S; the R
1
groups, equal or different from each other, are hydrogen or linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl or C
7
-C
20
arylalkyl groups; two or more R
1
may form together one or more saturated, unsaturated or aromatic rings;
m is 0, 1 or 2, and more specifically it is 0 when Z is O or S, it is 1 when Z is N or P, and it is 2 when Z is C, Si or Ge;
n is an integer ranging from 1 to 8;
A and A′, the same or different from each other, are divalent anionic groups selected from —O—, —S— and —N(R
2
)—, wherein R
2
is hydrogen, a linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl or C
7
-C
20
arylalkyl, optionally containing one or more atoms belonging to Groups 13-17 of the Periodic Table;
M is a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups of the Periodic Table of the Elements (IUPAC version);
the substituents L, the same or different from each other, are monoanionic sigma ligands selected from the group consisting of linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl and C
7
-C
20
arylalkyl groups, optionally containing one or more Si or Ge atoms; preferably, the substituents L are the same;
the substituents L′, the same or different from each other, are halogens or —OR
3
, wherein R
3
is hydrogen or a linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl or C
7
-C
20
arylalkyl group;
p is an integer ranging from 1 to 3; q is an integer ranging from 0 to 2, p+q being equal to the oxidation state of the metal M minus 2, and p+q being ≦3;
said process comprising the following steps:
(1) reacting a ligand of formula (H—A)(ZR
1
m
)
n
(A′—H) with about (2+p) molar equivalents of a compound of formula L
j
B or LMgL′, wherein A, A′, Z, R
1
, m, n, p, L and L′ have the meaning reported above; B is an alkaline or alkaline-earth metal; and j is 1 or 2, j being equal to 1 when B is an alkaline metal, and j being equal to 2 when B is an alkaline-earth metal; and
(2) reacting the product obtained from step (1) with about 1 molar equivalent of a compound of formula ML′
s
, wherein M and L′ have the meaning reported above; s is an integer corresponding to the oxidation state of the metal and ranges from 3 to 6.
DETAILED DESCRIPTION OF THE INVENTION
The process of the invention allows organometallic complexes to be obtained, wherein the metal bears one or more sigma-bonded hydrocarbon substituents, in a simple, rapid and economic way, leadin
Basell Technology Company BV
Nazario-Gonzalez Porfirio
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