The present invention provides an IR-absorbing dye of formula (I) or (II): ##STR00001## wherein Q.sup.1, Q.sup.2, Q.sup.3 and Q.sup.4 are the same or different and are independently selected from a C.sub.3-20 heteroarylene group comprising at least one N atom; M is selected from Si(A.sup.1)(A.sup.2), Ge(A.sup.1)(A.sup.2), Ga(A.sup.1), Mg, Al(A.sup.1), TiO, Ti(A.sup.1)(A.sup.2), ZrO, Zr(A.sup.1)(A.sup.2), VO, V(A.sup.1)(A.sup.2), Mn, Mn(A.sup.1), Fe, Fe(A.sup.1), Co, Ni, Cu, Zn, Sn, Sn(A.sup.1)(A.sup.2), Pb, Pb(A.sup.1)(A.sup.2), Pd and Pt; A.sup.1 and A.sup.2 are axial ligands, which may be the same or different, and are selected from --OH, halogen, --OR.sup.3, a hydrophilic ligand and/or a ligand suitable for reducing cofacial interactions; R.sup.3 is a selected from C.sub.1-12 alkyl, C.sub.5-12 aryl, C.sub.5-12 arylalkyl or Si(R.sup.x)(R.sup.y)(R.sup.z); and R.sup.x, R.sup.y and R.sup.z may be the same or different and are selected from C.sub.1-12 alkyl, C.sub.5-12 aryl, C.sub.5-12 arylalkyl, C.sub.1-12 alkoxy, C.sub.5-12 aryloxy or C.sub.5-12 arylalkoxy.Dyes of this type are especially suitable for use in netpage and Hyperlabel systems.