Optical information recording medium and novel immonium compound

1. An optical information recording medium comprising a substrate having provided thereon a recording layer capable of recording information by laser beam irradiation, wherein the recording layer contains:

an oxonol dye represented by formula (I-5):

wherein R 1 , R 2 , R 3 and R 4 each independently represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group or a heterocyclic group, L 1 , L 2 and L 3 each independently represent a methine group which may have a substituent, m represents 0, 1, 2 or 3, and X k+ is an onium ion represented by formula (I-2):

wherein R 5 and R 6 each independently represents a substituent, R 7 and R 8 each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group, the couples of R 5 and R 6 , R 5 and R 7 , R 6 and R 8 , and R 7 and R 8 each may be combined together to form a ring, and r and s each independently represents 0 or an integer of from 1 to 4, provided that when r and s each is 2 or more, the plurality of R 5 or R 6 groups may be the same or different; and

at least one compound represented by the following general formula (I):

wherein R represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group; X represents an anion; in represents 0, 1 or 2; A represents a group represented by general formula (II) or (III), wherein n represents 1; and at least one of all aromatic groups in existence is substituted by an aryl group having 6 to 18 carbon atoms, an acyl group having 2 to 18 carbon atoms, an alkylsulfonyl group having 1 to 18 carbon atoms, an arylsulfonyl group having 6 to 18 carbon atoms, an alkylsulfinyl group having 1 to 18 carbon atoms, an alkoxycarbonyl group having 2 to 18 carbon atoms, an aryloxycarbonyl group having 7 to 18 carbon atoms, an aryloxy group having 6 to 18 carbon atoms, an acyloxy group having 2 to 18 carbon atoms, a sulfonyloxy group substituted by a hydrocarbon group having 1 to 18 carbon atoms, a sulfamoyl group which may be substituted by a hydrocarbon group having 1 to 18 carbon atoms, a nitro group, a cyano group or a 4- to 7-membered heterocyclic group:

and wherein at least one of the substituents on the aromatic groups is a cyano or an acetyl group and is positioned at the meta-position relative to the carbon atom having N—(R) 2 as a substituent group.

2. The optical information recording medium according to claim 1 , wherein said at least one of the substituents on the aromatic groups of the compound represented by formula (I) is a cyano group.

3. The optical information recording medium according to claim 1 , wherein the compound represented by general formula (I) is compound (I-2), (I-14), (I-20) or (I-24):