First prepd by reduction of MnI2 with a Grignard reagent under CO pressure: Hurd et al., J. Am. Chem. Soc. 71, 1899 (1949). Improved prepns: Brimm et al., ibid. 76, 3831 (1954); Closson, ibid. 80, 6167 (1958); Podall et al., ibid. 82, 1325 (1960); Calderazzo, Inorg. Chem. 4, 293 (1965). Crystal structure: Dahl, Rundle, Acta Crystallogr. 16, 419 (1963); molecular structure: Almenningen et al., Acta Chem. Scand. 23, 685 (1969). Reviews: Organic Syntheses via Metal Carbonyls vol. 1, I. Wender, P. Pino, Eds. (Interscience, New York, 1968) passim; Anisimov et al., Usp. Khim. 37, 380-408 (1968); Russ. Chem. Rev. 37, 184-197 (1968) (English translation).