Diphosphine ligand and transition metal complex using the same

1. A transition metal complex having, as a ligand, a compound represented by the formula

wherein R 4 is a C 1-6 alkyl group optionally having substituent(s), and R 5 and R 6 are each a C 1-6 alkyl group optionally having substituent(s), or R 4 is a hydrogen atom or a C 1-6 alkyl group optionally having substituent(s), and the formula

is a group represented by the formula

wherein ring B is a 3- to 8-membered ring optionally having substituent(s).

2. The transition metal complex of claim 1 , wherein the transition metal is rhodium, ruthenium, iridium, palladium, nickel or copper.

3. The transition metal complex of claim 1 , wherein the transition metal is rhodium, ruthenium or palladium.

4. The transition metal complex of claim 1 , wherein R 4 is an unsubstituted C 1-6 alkyl group, and R 5 and R 6 are each an unsubstituted C 1-6 alkyl group.

5. The transition metal complex of claim 1 , which is selected from the following:

(1) [Ru(OAc) 2 (L)];

(2) [RuCl 2 (L)(dmf) n ];

(3) [RuCl(Ar)(L)]Cl;

(4) [Ru(2-methylallyl) 2 (L)];

(5) [RuCl 2 (L)(X)];

(6) (NH 2 Et 2 )[{RuCl(L)} 2 (μ-Cl) 3 ];

(7) [Rh(Y)(L)]Z;

(8) [PdCl 2 (L)]; and

(9) [{Pd(L)} 2 (μ-OH) 2 ]Z 2

wherein L is 2,2′-bis[bis(4-dimethylamino-3,5-dimethylphenyl)phosphino]-1,1′-binaphthyl, 2,2′-bis[bis(4-dimethylamino-3,5-diethylphenyl)phosphino]-1,1′-binaphthyl, 2,2′-bis[bis(4-dimethylamino-3,5-diisopropylphenyl)phosphino]-1,1′-binaphthyl, or 2,2′-bis[bis[4-(pyrrolidin-1-yl)phenyl]phosphino]-1,1′-binaphthyl, Ac is acetyl, dmf is N,N-dimethylformamide, n is an integer of not less than 1, Ar is benzene optionally having substituent(s), 2-methylallyl is η 3 -2-methylallyl, X is ethylenediamine, 1,2-diphenylethylenediamine or 1,1-di(4-anisyl)-2-isopropyl-1,2-ethylenediamine, Y is 1,5-cyclooctadiene or norbornadiene, Z is a counter anion and trifluoromethanesulfonate, tetrafluoroborate, perchlorate, hexafluorophosphate or tetraphenylborate.

6. A catalyst comprising the transition metal complex of claim 1 .

7. The transition metal complex of claim 1 , wherein R 4 is a hydrogen atom or a C 1-6 alkyl group optionally having substituent(s), and the formula

is a group represented by the formula

wherein ring B is a 3- to 8-membered ring optionally having substituent(s).