-0,0xe0x00x0-bis(diphenyl phosphino)-0,0xe0x00x0-biphenyl (abbreviated hereinafter to xe0x00x0cBIPHEMPxe0x00x0d), 0,0xe0x00x0-dimethyl-0,0xe0x00x0-bis(di-p-tolyl phosphino)-0,0xe0x00x0-biphenyl (abbreviated hereinafter to xe0x00x0cp-Tol-BIPHEMPxe0x00x0d), 0,0xe0x00x0-dimethyl-0,0xe0x00x0-bis(di-0,0-xylyl phosphino)-0,0xe0x00x0-biphenyl (abbreviated hereinafter to xe0x00x0cDM-BIPHEMPxe0x00x0d), 0,0xe0x00x0-dimethyl-0,0xe0x00x0-bis(di-0-methoxy-0,0-dimethylphenyl phosphino)-0,0xe0x00x0-biphenyl (abbreviated hereinafter to xe0x00x0cDMM-BIPHEMPxe0x00x0d), 0,0xe0x00x0-dimethyl-0,0xe0x00x0-bis(di-0-