Catalysts for ring opening polymerization

A method for ring opening polymerization, comprising contacting a substrate of Formula (I):

• wherein,
• X is a chemical bond, C(O), or C(O)O;
• when X is a chemical bond then Z is a chemical bond or the group —CR5R6—;
• and
• when X is C(O) or C(O)O then Z is a group —CR5R6—or a group of the formula —(CH2)Z—, wherein z is an integer from 0-6;
• R1 is selected from Rla, OR1a, N(R1a)2, SiR1a3, SR1a, SO2R1a, SO2N(R1a)2, C(O)R1a;
• C(O)OR1a, OCOR1a;
• C(O)N(R1a)2, OC(O)N(R1a)2, N(R1a)C(O)N(R1a)2, F, Cl, Br, I, cyano, and nitro, wherein R1a is in each case independently selected from hydrogen, C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aryl, C1-8heteroaryl, C3-8cycloalkyl, or C1-8heterocyclyl;
• R2 is selected from R2a, OR2a, N(R2a)2, SiR2a3, SR2a, SO2R2a, SO2N(R2a)2, C(O)R2a;
• C(O)OR2a, OCOR2a;
• C(O)N(R2a)2, OC(O)N(R2a)2, N(R2a)C(O)N(R2a)2, F, Cl, Br, I, cyano, and nitro, wherein R2a is in each case independently selected from hydrogen, C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aryl, C1-8heteroaryl, C3-8cycloalkyl, or C1-8heterocyclyl;
• R3 is selected from R3a, OR3a, N(R3a)2, SiR3a3, SR3a, SO2R3a, SO2N(R3a)2, C(O)R3a;
• C(O)OR3a, OCOR3a;
• C(O)N(R3a)2, OC(O)N(R3a)2, N(R3a)C(O)N(R3a)2, F, Cl, Br, I, cyano, and nitro, wherein R3a is in each case independently selected from hydrogen, C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aryl, C1-8heteroaryl, C3-8cycloalkyl, or C1-8heterocyclyl;
• R4 is selected from R4a, OR4a, N(R4a)2, SiR4a3, SR4a, SO2R4a, SO2N(R4a)2, C(O)R4a;
• C(O)OR4a, OCOR4a;
• C(O)N(R4a)2, OC(O)N(R4a)2, N(R4a)C(O)N(R4a)2, F, Cl, Br, I, cyano, and nitro, wherein R4a is in each case independently selected from hydrogen, C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aryl, C1-8heteroaryl, C3-8cycloalkyl, or C1-8heterocyclyl;
• R5, when present, is selected from R4a, OR4a, N(R4a)2, SiR4a3, SR4a, SO2R4a, SO2N(R4a)2, C(O)R4a;
• C(O)OR4a, OCOR4a;
• C(O)N(R4a)2, OC(O)N(R4a)2, N(R4a)C(O)N(R4a)2, F, Cl, Br, I, cyano, and nitro, wherein R5a is in each case independently selected from hydrogen, C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aryl, C1-8heteroaryl, C3-8cycloalkyl, or C1-8heterocyclyl;
• R6, when present, is selected from R6a, OR6a, N(R6a)2, SiR6a3, SR6a, SO2R6a, SO2N(R6a)2, C(O)R6a;
• C(O)OR6a, OCOR6a;
• C(O)N(R6a)2, OC(O)N(R6a)2, N(R6a)C(O)N(R6a)2, F, Cl, Br, I, cyano, and nitro, wherein R6a is in each case independently selected from hydrogen, C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aryl, C1-8heteroaryl, C3-8cycloalkyl, or C1-8heterocyclyl;
• wherein any two or more of R1, R2, R3, R4, R5, and R6 may together form a ring;
• with a catalyst system comprising a catalyst of Formula II and propagator of Formula III:
• wherein
• Nx is selected from N, P, As, Sn, and Pb;
• Bx is in each case independently selected from B, Al, Ga, In, and Th;
• Rb1, Rb2, Rb3, Rb4, Rb5, Rb6, and Rb7 are independently selected from are independently selected from C1-8alkyl;
• wherein any two or more of Rb1, Rb2, and Rb3;
• Rb4 and Rb5;
• or Rb6 and Rb7 may together form a ring;
• Rn1, Rn2, and Rn3 are independently selected from hydrogen and C1-8alkyl, wherein any two or more of Rn1, Rn2, and Rn3 may together form a ring;
• R7 is C1-8alkyl, or wherein R7 may form an C2-8 alkyl group with one or more of Rn1, Rn2, and Rn3;
• to give a ring opened polymer having the formula:
• wherein n is any integer,
• wherein the ring opening polymerization is conducted in a polar aprotic solvent, non-polar solvent, polar protic solvent, or a combination thereof.