Arsaalkenes R-As=C(NMe2)2 [R = PhC(O), 4-EtC 6H4C(O), 2,4,6-Me3C6H 2C(O), tBuC(O), Me3Si]: Versatile reagents in the chemistry of heterocumulenes

Article abstract of DOI:10.1021/om051084t

Reaction of [Cp(CO)₂M=P=C(SiMe₃)₂] (where M = Mo (3a), W (3b)] with 2 equiv of the arsaalkene PhC(O)As=C(NMe ₂)₂ afforded the metalloarsaalkenes Cp(CO) ₂M-As=C(Ph)-O-P-O-C(Ph)=As-C(SiMe₃)₂ [where M= Mo (6a), W (6b)]. Small amounts of [η³3:η³- (Me₃Si)₂CPAs-AsPC(SiMe₃)₂}-{Mo(CO) ₂Cp}₂] (7) were formed as a minor product. Similarly, 3b and 2 equiv of 4-EtC₆H₄C(O)As=C(NMe₂) ₂ gave rise to the formation of [Cp(CO)₂W-As=C(4-EtC ₆H₄)-O-P-O-C(4-EtC₆H₄)=As- C(SiMe₃)₂] (8). However, treatment of 3a and 3b with an excess of tBuC(O)As=C(NMe₂)₂ yielded cocrystals of the η³-2-phospha-1,3-diarsaallyl complexes [Cp(CO) ₂M{η³-tBuC(O)AsPAsC(O)tBu}] [where M = Mo (13a), W (13b)] and the η³-1,2,3-triarsaallyl complexes [Cp(CO) ₂M{η³-/BuC(O)AsAsAsC-(O)tBu}] [where M = Mo (14a), W (14b)] in varying ratios. Reaction of 3a with Me₃SiAs=C(NMe ₂)₂ afforded the dinuclear 1,2-diphosphapropene complex [η²:η²-(Me₃Si)₂C=P-P(H)-C(H) (SiMe₃)₂}{Mo-(CO)₂Cp}₂] (15). The novel compounds 6a,b, 8, 13a,b, 14a,b. and 15 were characterized by means of spectroscopy (IR and ¹H, ¹³C{¹H}, ³¹P NMR). Moreover the molecular structures of 7, 8, 13a, 14a, 13b, 14b, and 15 were determined by X-ray diffraction analyses.