Compounds for use as ligands

1. A metal complex comprising a metal and one or more ligands, wherein the metal is selected from the group consisting of rhodium, iridium, platinum, palladium, titanium, ruthenium and cobalt and at least one of the ligands is a compound of the formula (I):

wherein

R 1 is a cyclopentadienyl group;

X is an alkylene linker comprising at least two in-chain carbon atoms; and

Y is selected from the group consisting of ═O, —OH, ═S, —SH, —S(O), —S(O) 2 , NH 2 , amino or mono-substituted amino.

2. The metal complex according to claim 1 , wherein the compound is not selected from the group consisting of 1-(3-hydroxypropyl)-2,3,4,5-tetramethylcyclopentadiene, 1-(4-hydroxy butyl)-2,3,4,5-tetramethylcyclopentadiene, 1-(5-hydroxypentyl)-2,3,4,5-tetramethylcyclo pentadiene, 1-(3-aminopropyl)-2,3,4,5-tetramethytcyclopentadiene, 1-(4-aminobutyl)-2,3,4,5-tetramethylcyclopentadiene, 1-(5-aminopentyl)-2,3,4,5-tetramethylcyclopentadiene and 1-(8-heptadecenyl)2,3,4,5-tetramethylcyclopentadiene.

3. The metal complex according to claim 1 , wherein R 1 is tetramethylcyclopentadienyl.

4. The metal complex according to claim 1 , wherein X has 2 to 20 in-chain carbon atoms.

5. The metal complex according to claim 1 , wherein X is an alkenylene group.

6. The metal complex according to claim 2 , wherein Y is selected from the group consisting of ═O, —OH and —NH 2 .

7. The metal complex according to claim 1 , wherein Y is a mono-substituted amino group.

8. The metal complex according to claim 7 , wherein the amino group is substituted with a substituted C 1-6 alkyl, aryl, arylalkyl or heteroaryl group.

9. The metal complex according to claim 7 , wherein the mono-substituted amino group is N—(C 1-6 alkyl)amino, amino or tosyl amino.

10. The metal complex according to claim 1 , wherein the X and/or Y is selected from the group consisting of 2-hydroxyethyl, 3-hydroxy-n-propyl, 4-hydroxy-n-pentyl, 2-hydroxypropyl, 3-hydroxybutyl, 3-hydroxy-1-methylpropyl, 1-methylene-3-hydroxypropyl, 3-hydroxy-3-phenylpropyl, 2-oxopropyl, 3-oxobutyl, 4-oxopentyl, 3-aminopropyl, 5-aminopentyl, 3-propanoate and 5-pentanoate.

11. The metal complex according to claim 1 , wherein the metal is a transition metal.

12. The metal complex according to claim 1 , wherein the metal is rhodium or iridium.

13. The metal complex according to claim 1 , wherein the metal complex comprises one or more additional ligands.

14. A process for production of a metal complex comprising a metal and one or more ligands, the metal is selected from the group consisting of rhodium, iridium, platinum, palladium, titanium, ruthenium and cobalt and at least one of the ligands is a compound of formula (I):

wherein

R 1 is a cyclopentadienyl group;

X is an alkylene linker comprising at least two in-chain carbon atoms; and

Y is selected from the group consisting of ═O, —OH, ═S, —SH, —S(O), —S(O) 2 , amino and mono-substituted amino, wherein the process comprises

i) contacting a compound of formula (III):

wherein

X is an alkylene linker comprising at least two in-chain carbon atoms;

Y is selected from the group consisting of ═O, —OH, ═S, —SH, —S(O), —S(O) 2 , amino and mono-substituted amino;

each R 2 is independently an ethenyl group;

with an acid under conditions such that the R 2 groups and the carbon atom to which they are attached together form a cyclopentadienyl group; and

ii) contacting the compound of formula (I) with a metal to form the metal complex.

15. The metal complex according to claim 1 , further comprising a catalyst.

16. The metal complex according to claim 7 , wherein the amino group is substituted with a hydrocarbyl group, a heterocyclyl group or a heterocycloalkyl group.

17. The metal complex according to claim 16 , wherein the hydrocarbyl group, heterocyclyl group or heterocycloalkyl group are optionally attached to the nitrogen atom of the amino group via a linkage selected from the group consisting of —O—, C(O)—, —C(O)O—, —S—, —S(O)— and —S(O) 2 —.