Abstract The phase-transfer-catalytically in situ generated dihalocarbenes CCl2 and CBr2 are inserted into a β-C-H bond of the five-and six-membered phosphamanganacycloalkanes (OC)4[xxx] (1a, b) [n = 1(a), 2(b)] to give the functionalized metallacycles (OC)4[xxx](2a, a′, b, b′) [X = Cl: n = 1(a), 2(b); X = Br: n = 1(a′), 2(b′)]. 2b crystallizes in the orthorhombic space group Pbca with Z = 8 and has a distorted chair conformation with equatorial position of the CHCl2 group. The envelope conformation of 2a in solution was elucidated by means of 1H and 13C{1H} NMR spectroscopic investigations.