Large Third-Order Nonlinear Optical Susceptibilities of Multiply-Bonded M2(pyphos)4 and M2Pd2Cl2(pyphos)4 (M = Cr, Mo; Pyphos = 6-Diphenylphosphino-2-pyridonate) by Picosecond Degenerate Four-Wave Mixing Method

Multiply-bonded tetranuclear complexes M2Pd2Cl2(pyphos)4 (1) and dinuclear complexes M2(pyphos)4 (2)(a, M = Mo; b, M = Cr; pyphos = 6-diphenylphosphino-2-pyridonate) are found to exhibit large hyperpolarizability γ of nonlinear optical property by using the picosecond degenerate four-wave mixing (DFWM) method; the γ values of 1a (1.5 × 10−30 esu), 1b (5.2 × 10−31 esu), and 2a (6.9 × 10−31 esu) are greater than those (ca. 10−35—10−33 esu) of transition metal poly(yne) polymers.